Cover crops battle resistant weeds

Think Different

  • Plan cover crop mix for weed suppression as well as soil health.
  • Keep costs down with lower cost cereal rye and ryegrass.
  • Integrate herbicide program planning with cover crop planning for maximum return.

Ralph Upton has cut his herbicide costs, controlled herbicide resistant marestail and waterhemp, improved soil health and reducd erosion on his south central Illinois fields. And while the weather impacted his herbicide program, weed suppression by cover crops kept working.

“Where I had cover crops, I seldom saw weeds,” says Upton. “Waterhemp is hitting us real hard. We’ve had issues in the past, but nothing compared to this year.”

Wet, cold weather in April delayed planting until May 10, with additional rain delays keeping him out of the field until June 1. As a result, he planted only 200 acres of corn compared to his normal 800 to 900 acres. That same weather also led to poor herbicide burndown. After years of relying on glyphosate he tried alternatives, only to discover apparent PPO as well as glyphosate resistance in his waterhemp.

Fields with cover crops aren’t immune to waterhemp. “I did get a few coming through and where I did, I sprayed the field, but I should have spot sprayed,” he says. “We had corn fields with a hairy vetch cover crop that we didn’t put any herbicide on. Where I had to replant I did use herbicide, but even there it was on only eight to ten acres out of 80.”

Stifled winter annuals, marestail

Mark Anson also reports significant weed suppression with delayed weed seed germination using cover crops. Weed control combined with other benefits justifies Anson Farms continuing to invest in cover crops while looking for ways to reduce other costs. The 20,000-acre operation in southwest Indiana and southeast Illinois has about 65 percent of its acres in cover crops.

“We find that cover crops control winter annuals really well and my brother, who does a lot of the spraying, has pointed out fields that used to have heavy marestail pressure have very few out there,” says Anson. “We seeded cover crops in a river bottom field, leaving a 100 ft. perimeter bare. The cover cropped area was clean, but the 100 ft. perimeter was heavy with weeds.”

“We are clearly seeing weed suppression with cover crops,” says Larry Steckel, row crop weed specialist, University of Tennessee.  “If you have a good cover crop stand, you don’t have to worry about marestail and winter annuals. Sometimes you avoid that extra burndown needed for marestail and it’s a big help with summer annuals like Palmer pigweed. A decent cover crop stand can delay pigweed 20 to 30 days which buys time and puts less stress on resistance management.”

Steckel notes seeing the most consistent weed control with wheat/vetch, cereal rye/vetch or cereal rye/crimson clover combinations. He does admit that they can require a two-pass program to terminate, such as dicamba, a few weeks before planting and gramoxone behind the planter.

He also has found that cover crops can complicate pre-emerge herbicide programs. “Atrazine in corn or metribuzin in soybeans work better than others,” says Steckel. “Prowl or Dual seems to hang up on top (the soil) while encapsulated acetoclor works well.”

Green planting helps

Mike Plumer has three years of research (eight replications each year) to back up claims of marestail suppression with cover crops. “We saw 95 to 98 percent control,” reports Plumer, consultant, Conservation Agriculture and a former University of Illinois extension specialist. “The best control was with 60 to 80 pounds of cereal rye seeded the second or third week of October  – You can go lighter and still get weed control if planted early enough to tiller. If you’re shooting for full season weed control of a broad spectrum of weeds, let cereal rye grow until planting. If planting cereal rye into corn stubble, 25 to 30 pounds of nitrogen in fall can increase stand, improve growth going into winter and increase growth in the spring improving weed control.”

Upton tries to get vetch planted on soybean stubble by mid-October even if that means planting a shorter season soybean variety as he did this year. He aims to plant 35 to 40 pounds of cereal rye and 10 to 12 pounds of ryegrass on corn stubble by Thanksgiving.

He feels he is getting physical suppression from the rye combination, as well as some allelopathic affect. As he has focused more and more on weed suppression, he waits longer to terminate which adds more complications. “To get more biomass, we need to let it grow longer,” he says. “Increasingly, I will be terminating right at planting with glyphosate on the rye and 2, 4-D on the hairy vetch.”

Convince landlords of value

This year Upton had too much biomass. Delayed planting allowed up to 25 percent more biomass than usual. “The planter didn’t get set up right to handle it and that affected the stand which in turn allowed some water hemp to slip through,” he says.

Even with the complications, Upton, like Anson, has no plans to back off on his cover crop program. He is even considering expanding it to rental ground. “It has been hard to justify the cost on land you may not farm the following year,” he says. “However, I’m seeing enough weed control and other benefits that I may be able to convince landowners to work with me on it.”

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Weed control in no-tillage corn

Weed Control

Weed control in no-tillage corn is often more difficult  than in conventionally tilled corn. As a general rule, herbicide effectiveness decreases with the amount of crop and weed debris on the soil surface. This debris ties up herbicides and also presents a physical barrier to the uniform distribution of the herbicide on the soil for residual activity. Consequently, selection of herbicide rates and application methods is critical. Read and follow instructions on the herbicide label. On the other hand, residue cover provides some suppression of many weed species. In addition, there is generally less incidence of large-seeded weeds in continuous notillage systems.

Control of Existing Vegetation at  Planting

The types of weeds present and the type of cover determine the herbicide program required to control vegetation present at planting. It is necessary to consider the burndown materials and the postemergence characteristics of the other herbicides to be used in relationship  to the weed infestation.

Annual grasses and broadleaf weeds can be controlled with nonselective herbicides, such as glyphosate or paraquat. In general, no alteration in the residual herbicide program is needed to supplement the nonselective herbicide in these instances, although some herbicide labels require slightly higher rates to compensate for herbicide adsorption on the cover crop or other plant material.

When planting in perennial grass sods, a single paraquat application may not be sufficient to give satisfactory control. Control of orchardgrass and fescue requires use of the highest labeled rates of atrazine in addition to paraquat. The use of atrazine plus simazine combinations in perennial sods is not recommended because, unlike atrazine, simazine does not have postemergence activity and will not aid in burndown of these grass sods. In very vigorous orchardgrass or fescue sods, two applications of paraquat are sometimes required to achieve complete control.

The use of glyphosate should be considered for control of existing perennial broadleaf and grass weeds at planting. Care must be taken to allow these weeds to reach the minimum growth stages listed on the label before application is made. Often, this delays corn planting to the point that alternative crops or tillage methods should be considered as a means of control.

The use of glyphosate should also be considered when heavy infestations of annual weeds are present and have advanced to the stage at which paraquat will give only partial control.

Control of Annual Grasses

Fall panicum and other annual grasses can be major problems in no-tillage corn production. Simazine has good activity on annual grasses, and a combination of atrazine and simazine will give good control, especially of late-season flushes of these annual grasses. Chloroacetamide herbicides, including metolachlor, alachlor, and acetochlor, also provide good residual control of annual grasses and suppression of yellow nutsedge. These herbicides can be used in combination with atrazine, or in combination with atrazine and simazine.

Control of Triazine-Resistant Pigweed

Triazine-resistant pigweed is a major problem in a large part of our no-tillage corn acreage. The weed has no susceptibility to the triazine herbicides.Residual chloroacetamide herbicides afford fair-to-good control of this weed with optimum activation rainfall. If there is not  sufficient rainfall for activation or if very heavy rainfall occurs early in the season, pigweed control with these compounds will be inadequate, and a postemergence herbicide application will be required. Excellent preemergence residual control of pigweed can be obtained when flumetsulam, mesotrione, or pendimethalin are included in the pre-emergence herbicide application. These compounds are available in prepackaged mixes.

One product used extensively in Virginia no-till corn, Lumax, contains atrazine and metolachlor for general residual weed control, plus mesotrione for residual control of pigweed.

Control of Perennial Broadleaf Weeds

In the absence of tillage, herbaceous perennial broadleaf weeds can become very troublesome in no-till corn plantings. These species must be controlled with systemic herbicides at growth stages when translocation towards underground perennial plant structures is maximized. Generally, these perennials have not emerged at the time of planting, and making applications before planting are ineffective.

In most cases, the use of glyphosate-resistant corn hybrids represents the most effective overall method for perennial broadleaf weed control in no-till corn. Growers should also consider control of these perennials in rotational crops. Where soybeans are part of the rotation, perennial broadleaf weed control should be considered in glyphosate-resistant soybeans, because the soybean canopy is extremely effective in aiding the control of these species.

Control of Perennial Grasses

There are several excellent postemergence methods for perennial grass control in no-till corn. Johnsongrass can be controlled with nicosulfuron or with glyphosate in a glyphosate-resistant corn hybrid.Because of potential maize dwarf mosaic virus transmission to corn from dying johnsongrass following these applications, maize dwarf mosaic virus-tolerant corn hybrids must be used where postemergence johnsongrass herbicide programs will be employed.Bermudagrass control in no-till corn requires the use of glyphosate in glyphosate-resistant corn hybrids.Several postemergence herbicides, including halosulfuron, mesotrione, and glyphosate, can be used for the control of yellow nutsedge.

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Cover and Green Manure Crop Benefits to Soil Quality

Soil Quality and Resource Management

Soil is one of the five resources—soil, water, air, plants, and animals—that NRCS deals with in resource planning. Soil is intimately related to the other four resources, and its condition can either negatively or positively impact the other resources. For example, if the soil surface is functioning adequately, the soil will allow water to infiltrate, thus reducing the potential for erosion and increasing the amount of water stored for plant use. This function of soil affects water quality, plant growth, and the health of animals. In addition, protection of the surface layer resists wind erosion, thus protecting the air resource. Soil Quality is a critical factor in the management of natural resources, and the protection or enhancement of soil quality is the key component of all resource management assistance activities in the NRCS.

What is Soil Quality?

Soil quality is the capacity of a specific kind of soil to function within natural or managed ecosystem boundaries to:

* sustain plant and animal productivity

* maintain or enhance water and  air quality

* support human health and habitation.

As defined, the terms soil quality, soil health, and soil condition are interchangeable.

Effects of Conservation Practices

One of the goals of conservation planning is to consider the effects of conservation practices and systems on soil quality. This is the first technical note in a series on how conservation practices affect soil quality. This technical note is designed to compliment local or regional information on the specific nature of cover crops. Cover and Green Manure Crop Benefits to Soil Quality

1. EROSION – Cover crops increase vegetative and residue cover during periods when erosion energy is high, especially when main crops do not furnish adequate cover. Innovative planting methods such as aerial seeding, interseeding with cyclone seeder, or other equipment may be needed, when main crop harvest, delays conventional planting of cover crops during recommended planting dates.

2. DEPOSITION OF SEDIMENT – Increase of cover reduces upland erosion, which in turn reduces sediment from floodwaters and wind.

3. COMPACTION – Increased biomass, when decomposed, increases organic matter promoting increased microbial activity and aggregation of soil particles. This increases soil porosity and reduces bulk density. Caution: plant cover crops when soils are not wet, or use other methods such as aerial seeding.

4. SOIL AGGREGATION AT THE SURFACE – Aggregate stability will increase with the addition of and the decomposition of organic material by microorganisms.

5. INFILTRATION – Surface cover reduces erosion and run-off. Cover crop root channels and animal activities, such as earthworms, form macropores that increase aggregate stability and improve infiltration. Caution: Macropores can result in an increase in leaching of highly soluble pesticides if a heavy rain occurs immediately after application. However, if only sufficient rainfall occurs to move the pesticide into the surface soil after application, the risks for preferential flow are minimal. Cover crops, especially small grains, utilize excess nitrogen.

6. SOIL CRUSTING – Cover crops will provide cover prior to planting the main crop. If conservation tillage is used, benefits will continue after planting of main crop. Increases of organic matter, improved infiltration, and increased aggregate stability reduce soil crusting.

7. NUTRIENT LOSS OR IMBALANCE – Decomposition of increased biomass provides a slow release of nutrients to the root zone. Legume cover crops fix atmospheric nitrogen and provide nitrogen for the main crop. Legumes utilize a higher amount of phosphorus than grass or small grains. This is useful in animal waste utilization and management. Small grains are useful as catch crops to utilize excess nitrogen, which reduces the potential for nitrogen leaching. Caution: To prevent nutrient tie ups, cover crops should be killed 2-3 weeks prior to planting main crop. Tillage tools are used to kill and bury cover crops in conventional tillage systems. However, with conservation tillage systems, cover crops are killed with chemicals and left on or partially incorporated in the soil.

Caution: Research has shown that incorporation of legume cover crops results in more rapid mineralization. However, due to delay in availability of nitrogen from legume cover crop in conservation tillage, a starter fertilizer should be applied at planting. (Reeves, 1994). An ARS study done in Morris, Minnesota reported dramatically higher carbon losses through C02 remissions under moldboard plow plots as compared to no-till. It was reported that carbon was lost as C02 in 19 days following moldboard plowing of wheat stubble that was equal to the total amount of carbon synthesized into crop residues and roots during the growing season. Long-term studies indicate that up to 2 percent of the residual organic matter in soils are oxidized per year by moldboard plowing” (Schertz and Kemper, 1994).

8. PESTICIDE CARRYOVER – Cover crops reduce run-off resulting in reduced nutrient and pesticide losses from surface runoff and erosion. Increased organic matter improves the environment for soil biological activity that will increase the breakdown of pesticides.

9. ORGANIC MATTER – Decomposition of increased biomass results in more organic matter. Research shows cover crops killed 2-3 weeks prior to planting main crop, results in adequate biomass and reduces the risk of crop losses from soil moisture depletion and tie up of nutrients.

10. BIOLOGICAL ACTIVITY – Cover and green manure crops increase the available food supply for microorganisms resulting in increased biological activity.

11.WEEDS AND PATHOGENS – Increased cover will reduce weeds. Caution: Research has shown reductions in yield are possible in conservation tillage cotton systems following winter cover crops. Reductions are attributed to interference from residue (poor seed/soil contact), cool soil temperatures at planting, increased soil borne pathogens, and increased insects and other pests. Harmful effects from the release of chemical compounds of one plant to another plant (allelopathic) are possible with crops like cotton, but losses can be reduced by killing the cover crop 2-3 weeks prior to planting main crop, and achieving good seed/soil contact with proper seed placement. Cover crops have shown some allelopathic effects on weeds reducing weed populations in conservation tillage (Reeves, 1994).

12. EXCESSIVE WETNESS – Cover and green manure crops may remove excess moisture from wet soils, resulting in reduction of “waterlogging” in poorly drained soils. Caution: transpiration of water can be a detriment in dry climates. Planners should adjust the kill date of cover crops to manage soil water.


Cover and Green Manure Crops as a conservation practice can improve soil health. Soil quality benefits such as increased organic matter, biological activity, aggregate stability, infiltration, and nutrient cycling accrue much faster under no-till than other tillage practices that partially incorporate the residue.

One example comes from the Jim Kinsella farming operation near Lexington, Illinois. He reports that organic matter levels have increased from 1.9 percent 6.2 percent after 19 years of continuous no-till (Schertz and Kemper, 1994). Future technical notes will deal with other conservation practice effects on soil quality. The goal of the Soil Quality Institute is to provide this information to field offices to enable them to assist landusers in making wise decisions when managing their natural resources.

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Open System for Organic Agriculture Administration

Efforts to increase the availability of sustainable development in natural resources worldwide are  consecutive and proliferated through the last decades. Sectors and divisions of many scientific  networks are working simultaneously in separate schemas or in joined multitudinous projects and  international co-operations. Organic Agriculture, as a later evolution of farming systems, was  derived from trying to overcome the accumulative environmental and socioeconomic problems of  industrialized communities and shows rapid development during the last decades. Its products  day to day gain increased part of consumer preferences while product prices are rather higher  than those of the traditional agriculture. Governments all over the world try to reduce the  environmental effects of the industrialized agriculture, overproduction and environmental  pollution, encouraging those who want to place their fields among others that follow the rules  of organic agriculture. All the above make this new trend very attractive and promising.

But the rules in organic agriculture are very restrictive. The intensive pattern of cultivation  worldwide and the abuse of chemical inputs, affected the environment, therefore any field  expected to be cultivated under the rules of organic agriculture has to follow certain steps but  also be ‘protected’ from the surrounding plots controlling at the same time different kind of unexpected influx (e.g., air contamination from nearby insecticides’ use, water pollution of  irrigation system from an adjacent plot that has used fertilizers, etc). It is obvious that the gap  between wish and theory and the implementation of organic agriculture is enormous.

Obviously one can overcome this gap using a sophisticated complex system. Such a system  can be based on a powerful GIS and the use of widely approved mobile instruments for  precise positioning and wireless communication. In such a system data-flow could be an  “easy” aspect, providing any information needed for the verification of organic product cycle  at any time, any site. 


As the world’s population has increased from 1.6 billion at the beginning of the 20th century  to over 6.2 billion just before the year 2004, economic growth, industrialization and the demand for agricultural products caused a sequence of unfortunate results. This aggregation of disturbances moved along with the reduction in availability and deterioration of maximum yield results from finite ranges of plots on earth’s surface. Overuse of agrochemical products (insecticides, pesticides, fertilizers, etc.), reduction and destruction of natural resources, decrease of biodiversity, reduction of water quality, threat over rare natural landscapes and wild species and an overall environmental degradation, appeared almost daily in news worldwide especially over the last two decades. The universal widespread of this situation has raised worldwide awareness of the need for an environmentally sustainable economic development. (WCED, 1987) In the beginning of year 2004, EU Commission for Agriculture, Rural Development and Fisheries declared three major issues towards a European Action Plan on organic food and farming that may be crucial for the future of organic agriculture:

− the market, (promotion and distribution)

− the role of public support and,

− the standards of organic farming.

It is obvious that in general the market has a positive reaction if there is a prospect of considerable gain. Thus we can say that the other two will define the future. The strict rules of organic agriculture have to be ensured and all the products have to be easily recognisable.Also a guarantee about the quality and the origin of any product has to be established.

Organic Farming is derived as a sophisticated sector of the evolution of farming implementation techniques aiming through restrictions and cultivated strategies to achieve a balanced production process with maximum socioeconomic results (better product prices, availability of surrounding activities as ecotourism, family employment in low populated villages, acknowledge of natures’ and rural environments’ principles and needs, etc.). Meanwhile, the combination of latest technological advances, skills, innovations and the decline of computer and associate software expenses were transforming the market place of geographic data. Now, more than ever before, common people, farmers, private enterprises, local authorities, students, researchers, experts from different scientific fields, and a lot more could become an important asset supporting the development of innovations of Informatics in Geospatial Analysis. With the use of Geographic Information Systems and Internet applications various data can be examined visually on maps and analyzed through geospatial tools and applications of the software packages. Much recent attention and efforts has been focused on developing GIS functionality in the Worldwide Web and governmental or private intranets. The new applicable framework, called WebGIS, is surrounded with a lot of challenges and is developed rapidly changing from day to day the view of contemporary GIS workstations.

Precision Organic Agriculture through GIS fulfils the demands of design strategies and managerial activities in a continuing process. By implementing this combination, certified methods for defining the best policies, monitoring the results and the sustainability of the framework, and generating a constructive dialogue for future improvement on environmental improvement and development could be developed.


Organic Agriculture is derived from other organized smaller natural frameworks, publicly known as ecosystems which are complex, self-adaptive units that evolve through time and natural mechanisms and change in concern with external biogeochemical and natural forces.

Managing ecosystems should have been focused on multiplication of the contemporary needs and future perspectives to ameliorate sustainable development. Instead, political, economic and social agendas and directives, as well as scientific objectives resulted in few decades such an enormous amount of global environmental problems like never before in the history of mankind. Valuable time was spent over the past 75 years by research, which was trying to search how ecosystems regulate themselves, for example how they adjust to atmospheric, geologic, human activities and abuse (Morain, 1999).

Organic Agriculture flourished over the last decade particularly after 1993 where the first act of Regulation 2092/91 of European Union was enforced. Until then, and unfortunately, afterwards, worldwide environmental disasters ( e.g., the Chernobyl accident of the nuclear reactor in April 1986), accumulative environmental pollution and its results (acid rain, ozone’s hole over the Poles, Greenhouse effect, etc.) and even lately the problems that occurred by the use of dioxins and the propagation of the disease of “mad cows”, increase in public opinion the relation between natures’ disturbances and the continuing abuse of intensive methods of several industrialized chains of productions. Among them, conventional agricultural intensive production with the need of heavy machinery, enormous needs of energy consumptions and even larger thirst for agrochemical influxes the last fifty years, created environmental disturbances for the future generations. Therefore, IFOAM (International Federation of Organic Agriculture Movements) constituted a number of principles that, enabling the implementation of Organic Farming’s cultivation methods, techniques and restrictions worldwide.

Principles of Organic Agriculture Organic Agriculture:  (Source: IFOAM)

  •  aims on best soil fertility based in natural processes,
  •  uses biological methods against insects, diseases, weeds,
  • practices crop rotation and co-cultivation of plants
  • uses “closed circle” methods of production where the residues from former cultivations or other recyclable influx from other sources are not thrown away, but they are incorporated, through recycling procedures, back in the cultivation (use of manure, leaves, compost mixtures, etc.),
  • avoids heavy machinery because of soil’s damages and destruction of useful soil’s microorganisms,
  • avoids using chemicals,  avoids using supplemental and biochemical substances in animal nourishing,
  •  needs 3-5 years to transit a conventional cultivated field to a organic farming system following the restrictions of Council Regulation (EEC) No 2092/91,
  • underlies in inspections from authorities approved by the national authorities of Agriculture.

An appropriate organic plot should be considered as the landscape where ecological perspectives and conservations activities should be necessary for effective sustainable nature resource management (Hobs, 1997). Considerable amounts of time and effort has been lost from oncoming organic farmers on finding the best locations for their plots. Spatial restrictions for placing an organic farm require further elaboration of variables that are affecting cultivation or even a unique plant, such as:

− Ground-climatic variables (e.g., ground texture, ph, slope, land fertility, history of former yields, existence of organic matter, rain frequency, water supply, air temperature levels, leachability, etc.),

− Adjacency with other vegetative species (plants, trees, forests) for propagation reasons or non-organic cultivations for better controlling movements through air streams or erosion streams (superficial or in the ground) of agrochemical wastes,

− Availability of organic fertilization source from neighbored agricultural exploitations,

− Quality of accessing road network for agricultural (better monitoring) and marketing (aggregated perspectives of product distribution to nearby or broadened market area) reasons.

A GIS is consisted of computerized tools and applications that are used to organize and display geo-information. Additionally it enables spatial and non-spatial analysis and correlation of geo-objects for alternative management elaborations and decision making procedures. This gives the ability to GIS users or organic farm-managers to conceive and implement alternative strategies in agricultural production and cultivation methodology.


The development of first concepts and ideas of a precision organic farming system in a microregion, demands a regional landscape qualitative and recovery master plan with thorough and comprehensive description of the territory (land-use, emission sources, land cover, microclimatic factors, market needs and other essential variables. Essential components on a successful and prospective organic GIS-based system should be:

− The time-schedule and task specification of the problems and needs assessments that the design-strategy is intended to solve and manage,

− Integrated monitoring of high risks for the cultivation (insects, diseases, water quality, water supply, weather disturbances (wind, temperature, rain, snow, etc.),

− Supply of organic fertilization because additional needs from plants in certain periods of cultivation could be not managed with fast implemented agrochemicals; instead they need natural fermentations and weather conditions to break down elements of additional fertilization,

− High level of communication capabilities with authorized organizations for better management of the cultivation and geodata manipulation, aiming on better promotional and economical results,

− Increased awareness of the sustainability of the surrounding environment (flora and fauna), enabling motivation for a healthy coexistence. For example, the conservation of nearby natural resources such as rare trees, small bushes and small streams, give nest places and water supply capabilities to birds and animals that help organic plants to deal with insect populations controls and monitoring of other plant enemies,

− Continual data capture about land variables, use of satellite images, georeference  sampling proccedures and spatial modelling of existed or former geospatial historical plot’s data could be used to establish a rational model which will enable experts and organic farmers to transform the data into supportive decision applications.

The combination and modeling of all necessary variables through any kind of methodological approach, could be achieved through GIS expressing the geographical sectors of land parcels either as a pattern of vector data, or as a pattern of raster data (Kalabokidis et al., 2000). Additionally, we could allocate the cultivation or the combination of cultivations1 and their units (plants, trees, etc.) so as to be confronted in relation with their location inside the field, as well as with the neighbored landscape. For this purpose the most essential tool would be a GPS (Global Positioning System) device with high standards of accuracy. Several statistical approaches and extensions have been developed for the elaboration of spatial variables through geostatistical analysis. The usefulness of these thematic maps lies upon the tracing and localization of spatial variability in the plot during the cultivated period, enabling the farmer to implement the proper interferences for better management and future orientation of the farm and of the surrounding area.

Specific geodata receivers and sensors inside the plot, in the neighbored area, as well as images from satellites, could establish a “temporal umbrella” of data sources of our farm which would submit in tracing of temporal variability factors in our field. The agricultural management framework that takes into account the spatial or temporal variability of different parameters in the farm is called Precision Agriculture (Karydas, et al., 2002). The implementation of IFOAM’s principles in such an agricultural model should be called Precision Organic Agriculture (POA).


The development of appropriate analytical techniques and models in a variety of rapidly changing fields using as cutting edge GIS technology, is a high-demanding procedure. The linkages to different applications of spatial analysis and research and the ability to promote functional and integrated geodatabases is a time consuming, well prepared and carefully executed procedure which combines spatial analytic approaches from different scientific angles: geostatistics, spatial statistics, time-space modeling, mathematics, visualization techniques, remote sensing, mathematics, geocomputational algorithms and software, social, physical and environmental sciences.

An approach of a Precision Organic Farming model, which uses as a structure basis the Precision Agriculture wheel (McBratney et al., 1999) and the introduction of organic practices for the sustainable development with the elaboration of any historical data about the plot. The basic components are:

− Spatial referencing: Gathering data on the pattern of variation in crop and soil parameters across a field. This requires an accurate knowledge of allocation of samples and the GPS network.

− Crop & soil monitoring: Influential factors effecting crop yield, must be monitored at a thoroughly. Measuring soil factors such as electric conductivity, pH etc., with sensors enabling real-time analysis in the field is under research worldwide with focusing on automation of results. Aerial or satellite photography in conjunction with crop scouting is becoming more available nowadays and helps greatly for maximizing data acquisition for the crop.

− Spatial prediction & mapping: The production of a map with thematic layers of variation in soil, crop or disease factors that represents an entire field it is necessary to estimate values for unsampled locations.

− Decision support: The degree of spatial variability found in a field with integrated data elaboration and quality of geodata inputs will determine, whether unique treatment is warranted in certain parts. Correlation analysis or other statistical approaches can be used to formulate agronomically suitable treatment strategies.

− Differential action: To deal with spatial variability, operations such as use of organic-“friendly”-fertilizers, water application, sowing rate, insect control with biological practices, etc. may be varied in real-time across a field. A treatment map can be constructed to guide rate control mechanisms in the field.

GIS systems from their beginning about than 30 years ago, step by step, started to progress from small applications of private companies’ needs to high demanding governmental applications. At the beginning, the significance and capabilities of GIS were focusing on digitizing data; today, we’ve reached the last period of GIS’s evolution of data sharing. Nowadays restrictions and difficulties are not upon the hardware constraints but they are on data dissemination. Several initiatives have been undertaken in order to provide basic standard protocols for overcoming these problem. The need of organisational and institutional cooperation and establishment of international agreement framework becomes even more important. Governments, scientific laboratories, local authorities, Non Governmental Organizations (NGOs), private companies, international organizations, scientific societies and other scientific communities need to find substantial effort to broaden their horizons through horizontal or vertical standards of cooperation.

Any GIS laboratory specialized in monitoring a specific field could give additional knowledge to a coherent laboratory which focus to an other field in the same area. As a result, especially in governmental level, each agency performs its own analysis on its own areas, and with minimal effort cross-agency interactions could increase the efficiency of projects that help the framework of the society.

Such a data-sharing framework was not capable in earlier years, where technological evolution was trying specific restrictions of earlier operational computerised disabilities. Hardly managed and high demanding knowledge in programming applications, unfriendly scheme of computer operating systems over large and expensive programs, and restricted knowledge on Internet applications now belong to the past. User friendly computer operation systems, high storage capacity, fast CPUs (Central Processing Units) sound overwhelming even in relation with PCs before ten years. Powerful notebooks, flexible and strong PDAs, super-computers of enormous capabilities in data storage, true-colour high resolution monitors and other supplementary portable or stable devices, created an outburst in the applications of Information Technology (IT). Additionally, the expansion of Internet in the ‘90s worldwide, contributed (and is still keeping on doing this) on redesigning specific applications for data mining procedures through WWW (World Wide Web), as well as for data exporting capabilities and maps distribution through Internet. The evolution in computer software derived new versions of even friendlier GIS packages.


The Internet as a system followed an explosive development during the past decade. The modern Internet functions are based on three principles (Castells, 2001):

 − Decentralized network structure where there is no single basic core that controls the whole system.

− Distributed computing power throughout many nodes of the network.

− Redundancy of control keys, functions and applications of the network to minimize risk of disruption during the service.

Internet is a network that connects local or regional computer networks (LAN or RAN) by using a set of communication protocols called TCP/IP (Transmission Control Protocol/Internet Protocol). Internet technology enables its users to get fast and easy access to a variety of resources and services, software, data archives, library catalogs, bulletin boards, directory services, etc. Among the most popular functions of the Internet is the World Wide Web (WWW). World Wide Web is very easy to navigate by using software called browser, which searches through internet to retrieve files, images, documents or other available data.

The important issue here is that the user does not need to know any software language but all it needs is a simple “click” with mouse over highlighted features called Hyperlinks, giving  increased expansion on growth of WWW globally.

GIS data related files (Remote Sensing data, GPS data, etc) can benefit from globalization of World Wide Web:

− An enormous amount of these data are already in PC-format.

− GIS users are already familiar by using software menus.

− Large files could be easily transmitted through Internet and FTPs and software about compression.

− The Web offers user interaction, so that a distant user can access, manipulate, and display geographic databases from a GIS server computer.

− It enables tutorials modules and access on educational articles.

− It enables access on latest achievements in research of GIS through on-line proceedings of seminars, conferences, etc.

− Through Open Source GIS, it enables latest implementations of GIS programming and data sharing by minimum cost.

− Finally through online viewers, it gives the capability of someone with minimum  knowledge on GIS to get geospatial information by imaging display. (Aber, 2003)

The importance of World Wide Web could become more crucial through wireless Internet access. For a GIS user who works on the street, or in our case, on the field of an organic farm and uses wireless access to the web, a GIS package through a portable device, data transmission is an important issue. This is more important especially if the data are temporalaffected (e.g., meteorological data). To overcome this problem, new data transmission methods need to be elaborated and used in web-based GIS systems to efficiently transmit spatial and temporal data and make them available over the web. Open Source GIS through Internet represents a cross-platform development environment for building spatially enabled functions through Internet applications. Combinations of freely available software through WWW (e.g., image creation, raster to vector, coordinates conversion, etc), with a  combination of programming tools available for development of GIS-based applications could provide standardized geodata access and analytical geostatistical tools with great diplay efficiency. Under this framework, several geospatial applications can be developed using existing spatial data that are available through regional initiatives without costing anything to the end user of this Open GIS System (Chakrabarti et al., 1999).


As the World Wide Web grew rapidly, sophisticated and specialized methods for seeking and organizing data information have been developed. Powerful search engines can be searched by key words or text phrases. New searching strategies are under development where web links are analyzed in combination with key words or phrases. This improves the effectiveness at seeking out authoritative sources on particular subjects. (Chakrabarti et al., 1999) Digital certification under international cooperatives and standards is fundamental for the development of organic agriculture in general and particularly in the market framework. Based on the theory of “dot per plot” different functional IDs could be created under password protected properties through algorithm modules. This way, a code bar (like those on products in supermarkets) could be related through GIS by farmers ID, locations ID, product ID, parcel ID and could follow this product from organic plot to market places giving all the details about it. Even more, authorization ID could be established this way for controlling even the farmer for cultivated methods undertaken in the field that are underlie EUs’ legislations and directives.

 In many cases the only way to create or maintain a separate “organic market” is through certification which provides several benefits (Raghavan, et al., 2002):

− Production planning is facilitated through indispensable documentation, schedules, cultivation methods and their development, data acquisition (e.g., lab results on soil’s pH, electrical conductivity, organic conciseness, etc.) and general production planning of the farm − Facilitation of marketing, extension and GIS analysis, while the data collected in the process of certification can be very useful as feedback, either for market planning, or for extension, research and further geospatial analysis.

− Certification can facilitate the introduction of special support schemes and management scenarios for organic agriculture, since it defines a group of producers to support.

− Certification tickets on products under international standards improve the image of organic agriculture in the society as a whole and increases the creditability of the organic movement.

Because a certification ticket is not recognised as a guarantee standard by itself, the level of control system in biological farming is quite low. In Greece, we are familiar with farmers having a bench by the road and using hand made tickets for their products, they call them “biologic” aiming in higher prices. Marketing opportunities for real organic farmers are eliminating while at the same time EU is trying to organize the directives for future expansion of organic agriculture.

Designing a functional infrastructure of a Geodatabase, fully related with Internet applications, requires accumulative levels of modular mainframes that could be imported, managed and distributed through WWW applications. The security and reliability of main GIS databases have to be established and confirmed through international standards (ISOs) and authorized GIS packages and users as well as in relation with governmental agencies. On the next level, additional analysis of geodata files and agricultural related information data should be combined and further elaborated. For the base level, fundamental GIS functions and geodata digitization should be implemented through internetic report applications (HTML reports, site-enabled GIS, wireless GIS applications, etc.). By this framework we could create a data base where using any ID number (farmer, product, field, etc) will be easy to recognize the history of any specific item involved in the life cycle of the organic farming through a data-related link over thematic maps by GIS viewers in the Internet. Although this framework is supported by multifunctional operations, we could distinguish sectors with homogeneity features:

In the first level of accessing an Open GIS Web system, the users should be first able to access the system through a Web browser. Free access should be available here for users who want to retrieve information, as well for users who want to login for further, more advanced queries. Fundamental GIS functions and geodata digitization should be implemented through internetic report applications (HTML reports, site-enabled GIS, wireless GIS applications, etc.). In this level public participation is enabled through importing additional geodata sets and any other kind of information resources (for example, latest weather information, market demands, research accomplishments, latest equipment facilities, personal extensions for GIS packages, etc.). The eligibility of these data should be applied after studying standards criteria in the next level by experts. Technological advances are also providing the tools needed to disseminate real-time data from their source to the web mapping services, available to the users through the Internet, portable devices, cellular telephones, etc. Basic field work for agricultural and Remote Sensing purposes, as well as data gathering for further statistical analysis should be implemented. By this level, the user could access the system through browsing commands or hyperlinks and through GIS queries. The significant point here is that the access is completely free for anyone who wants to retrieve information but classified to everyone who wants to submit any kind of information by the meaning that he has to give either a user’s ID or personal details.

The second level of accessing the system , is the authorized expert’s level. Here additional analysis of geodata files and agricultural related information data should be combined and further elaborated. Expert analysts from different scientific fields (GIS, economists, topographers, agriculturists, ecologists, biologists, research, etc.) are “bridging” the two levels of the system by using high sophisticated computer tools and GIS packages to facilitate data transportation through WWW channels between clients and servers. In the database file an identity code (IdC) or feature code (FC) is distributed, following the geodata file from main Geodatabase server to the final user. By this framework we could create a data base where using any ID number (farmer, product, field, etc) will be easy to recognize the history of any specific item involved in the life cycle of the organic farming through a data-related link over thematic maps by GIS viewers in the Internet. Additional demand on this level should be considered to be indispensable a background in Web functions with further support by Web experts for adequate Web System Administration.

In the third level of this Web based GIS system,  the success is relying on cooperation between authorized users only. This partnership should be established between geographic information data providers and data management authorities at a governmental, local or private level by authorized personnel. International collaboration could provide even better results in data quality and quantity but requires additional data storage capabilities and special awareness on data interoperability and standards interchange eligibility confirmed through international standards (ISOs). The security of personal details must be followed enriching this level with further authorization controlling tools. The significance of designing successful strategies for case management, using authorized, legitimate GIS packages should also be supported through Web applications and algorithms available for GIS-Web users on global based patterns .


The generally accepted purpose of organic agriculture is to meet the needs of the population and environment of the present while leaving equal or better opportunities for those of the future. Development of this sector is increasing through coordinated activities worldwide by international organizations (EU, UN, FAO, etc.) with long-lasting master plans. The dynamic factor of organic agriculture should not be kept without support. Political initiatives should stand side by side with organic farmers helping them to increase the quality of products and to multiply the number of producers and of the cultivated area.

The accumulative development of Organic Agriculture in Europe needs to be followed by additional development of management activities and strategies in national, binational and international level. Combined actions should be undertaken in fields like telecommunications standards, computer software and hardware development, research projects on agricultural management through GIS, additional educative sectors in universities.

The restrictions that accompany organic farming should help in establishing international agreements that will help to increase the number of qualitative standards, allowing better perspectives for developing future GIS based management strategies. The implementation of an Internet Based Precision Organic Agricultural System requires committed research from the agricultural industry and improvements in geoanalysis, agricultural and information technology. GIS based systems will become more essential as a tool to monitor agricultural exchanges between inputs and outputs and in relation with adjacent regions at an increasingly detailed level. The results will enhance the role of Geographic Information as a functional and economic necessity for any productive community.

(Source –

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Weed management in No-till: improving the system

Why do we always face with problem of weeds? Because we allow them either to set seed on our ownership  or to be brought in on vehicles, in seed or hay etc… (poor hygiene), or via wind or water. There is the main problem with economic weed control. It allows weeds to continue setting seed, which means we keep on having to fight  them. The idea is not to use  more (e.g. quantity of herbicides) , but be wiser (use quality) . Having  a goal  100% weed control is the right  thing to do. Imagine sowing wheat on the day you wanted to (even if dry) because you knew there were no weed problems. It is achievable.

The principles are:

1) Be multifarious in your strategies.

a. Never use a consistent rotation (it is wrong to try and find one).

b. Never use the same chemicals all along.

c. Shift the growing season.

d. Use all options.

2) Be hygienic.

a. no introduced weeds from outside the farm.

b. and no “nurseries” where weeds can proliferate, like on fence lines.

By now in No-till you should have a good understanding on why we use herbicides in another way than with full cut sowing systems. No-till drives weeds to be more on the surface among the ants and stubble, and suffer from wet/dry cycles.

Soil residual or coleoptile active herbicides close to the seeds therefore work much better, hence the bigger use of trifluralin (Treflan), triallate (Avadex), metolachlor (Dual), oryzalin (Surflan and Yield).

When devising a rotation, removing a weed or pest problem needs to be right up there  with the thought  “what will bring me the biggest income now, and in the next few  years?”

Have a ryegrass problem? Then two or three years of complete (100%) weed control needs to be your goal. Rotations like hay, then peas (crop-topped) followed by herbicide tolerant canola would clean your paddock up very nicely, and then you should be able to have 2-4 years of cheap but high yielding cereal crops. You should be able to keep the paddock very low in weeds if you manage it well.

This is one more useful idea  for greater productivity, less  cost, more profit, and higher potential to get 100% weed control. So what is the secret?

Principle 1-c above mentioned shifting the growing season. That does partly mean sowing early and late with our normal winter crops, but it more importantly means planting other crops that are planted at very different times of the year, like in August  and September.

With autosteer and shielded sprayers, sunflowers, corn  and other crops become one of the best crops to grow, especially sunflowers. Even in paddocks with a broadleaf weed problem, you could sow these (in August to early September) on 1m row spacings.

On the row, you can spray herbicides at a high rate, but cheaply because you are only spraying a small percent of the paddock, and in between the rows you can use total weed kill herbicides like Roundup, Sprayseed, Gramoxone, Affinity, Pledge, Basta etc…. When herbicide tolerant sunflowers become more available, this will become even easier.

On legume winter crops, trials and experience is showing we should definitely grow these on wider row spacings, for yield reasons, but it also opens up very nicely to the shielded spraying strategy. On wide rows, we can spray Sprayseed down between the rows without damaging  the crop. This cannot be done on 7” rows. Canola is also looking OK on wider row spacings, as in 50-60cm at least.

There is a trade-off with wide rows on cereals. In South Australia particularly, your researchers have been pushing narrow rows to rise crop competition over the weeds. There is no doubt this is a valid finding, but I disagree with it when implemented on the farm.

Narrow rows means it is more unsafe  to use chemicals like trifluralin, and they influence less because of the increased soil disturbance and weeds being distributed to different depths. The increased soil disturbance makes more weeds germinate, which means the only way of controlling them in the crop is by herbicide or crop competition.

But if you use wider rows, it makes less weeds germinate, and trifluralin type chemicals work better. We are very comfortable growing wheat and barley at 250-300mm row spacing in WA.

Theoretically 100mm spacings would be higher yielding in a perfect world, but we have weeds, herbicide placement, stubble, pulling power etc… to contend with. Going wider to make herbicides work better and weeds germinate less is a useful thing. There is a point where yields wont be lower than yields at 100mm spacings, and we think this is approximately 250-300mm area. I would never go narrow just to smother weeds. On herbicides, thinking here on wheat and barley, never just use one herbicide. If you

have a weed problem, use a mixture of herbicides. In WA, a common mixture is with Diuron, metolachlor, trifluralin and triallate pre-sowing. Diuron is almost always used, and then with 2-3 of the other chemicals. Logran B-Power is sometimes used after a legume crop for wheat. SU’s should never be used on cereals after canola, or in any situation where nematodes are a problem. Never use harrows in no-till unless there is a very good reason, and herbicide incorporation is not one of those reasons.

Making weeds germinate is not good. It means you then have to use chemicals to destroy them.

It is important to remember that No-till also enables the use of old chemicals like oryzalin (Surflan and is in Yield). This is the same chemistry family as trifluralin, but is very residual. In full cut sowing, it is too damaging to cereals, but it is much safer in no-till. With Yield and Surflan now dropping in price, these will be used more where we can in canola and legume crops, and in the odd cereal crop until we get more experience, and if registrations allow.

Kerb (propyzamide) is still threatening to drop in price and when it gets down to the $20/kg mark or less, it will become a widely used herbicide in no-till in canola and some legume crops and pastures (registrations allowing of course).

So in conclusion, concentrate on the two principles mentioned at the beginning, try to move into autosteer and shielded spraying, and plan on rotations that remove a weed problem from your paddock.

(Based on –

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