Frequently Asked Questions (FAQs)

1. Does adoption of CA lead to increased compaction of agricultural soils?

2. Where are nutrient supplies coming from under CA cropping systems?

3. Is it true that farmers typically must wait 4-5 years until agricultural yields reach those attained under successful conventional agricultural systems?

4. What are the recommended first steps one should take when considering a transition to conservation agriculture?

5. Are there increased pest and weed problems under CA?

6. Why should one consider adopting CA if adequate yields and profits are being realized using conventional practices?

7. Doesn't conservation agriculture only work for growing grain crops?

8. Doesn't conservation agriculture only work for large-scale mechanized farms?

9. Isn't tillage necessary for increasing water infiltration and soil aeration?

10. Are chemical herbicides necessary in order to control cover crops before planting primary food crops under conservation agriculture?

11. Are nutrient losses higher under conservation agriculture?

1. Does adoption of CA lead to increased compaction of agricultural soils?

   In some cases, higher bulk densities under CA have been observed. However, this can be corrected by controlling traffic and limiting the number of passes over agricultural fields, particularly when soils are wet and most prone to compaction. For animal powered and manual systems, compaction would be less than where full tillage is given. Compared to conventional tillage, which often requires multiple passes of a tractor during a typical growing season, CA uses one pass to sow the seed/crop, thereby helping to reduce compaction issues in the long run. Perhaps even more important than measuring the bulk densities of particular soils is looking at other indicators of a healthy soil, including aggregate stability, porosity, infiltration, and biological activity among others. Soils under CA are typically much healthier than tilled soils due to the lack of soil disturbance and the building up of soil organic matter (SOM), especially on the surface where plant residues form a soil protective layer (lower erosion, soil loss) and provides food for increasing biological diversity. Earthworm and previous crop root channels are also not disturbed in CA systems and these act as very good soil pores for drainage of water. Recent research data shows that infiltration of water in CA systems is greater than in conventionally tilled plots as long as ZT is combined with residue cover.

2. Where are nutrient supplies coming from under CA cropping systems?

   Farmers may choose to apply either chemical or organic fertilizers to meet crop requirements, though decomposing crop residues from green manure cover crops (GMCCs), other cover crops and previous crops also supply essential nutrients. One important distinction between CA and other agricultural systems is that crop residues are left on the soil surface and are not incorporated into the soil. Chemical and organic fertilizers, however, should be banded into the soil with minimal soil disturbance if possible using the appropriate planting equipment. The result of improved biological activity in CA soils means more nutrient recycling and a better nutrient supplying capacity of the soil. However, for high yield, some additional external nutrients may need to be applied. It may be difficult to band bulky organic fertilizers and these can be placed as a mulch on the soil surface where microbes utilize and break them down in forms available to plant roots.

3. Is it true that farmers typically must wait 4-5 years until agricultural yields reach those attained under successful conventional agricultural systems?

   Though some farmers have reported lower yields during early stages of adoption of CA, many others have reported comparable or increased agricultural yields during this same period. Early success under CA has as much to do with agroecological conditions as with farmer experience and knowledge in land management. No-till farmers in South Asia have experienced early success and higher yields with NT wheat due to their ability to plant their crops closer to their optimal planting dates since they no longer use valuable planting time for tillage operations, but also Phalaris minor germination was reduced in undisturbed soil and so was less of a problem. In other cases, the condition of the soil must be significantly improved before agricultural yields can be maintained or improved. For example, heavily compacted soils low in soil organic matter (SOM) content require a longer transition phase than healthier soils with higher levels of SOM. These soils can be deep tilled with equipment that breaks the plow pan or remedied by growing cover crops and incorporating organic amendments into the soil even before converting to a strict no-till (NT) system. During this "transition phase," farmers must carefully monitor changes in soil quality and effectively manage pest and weed problems. If all this is done properly and according to the specific on-farm conditions and management desires of the farmer, agricultural yields will likely be maintained or increased under CA, as compared to conventional production systems. It may take several years for the soil to visibly show improved properties and health. Note that farmers benefit from adopting CA in the first year by reducing the costs of establishing the crop.

4. What are the recommended first steps one should take when considering a transition to conservation agriculture?

   One should first try to obtain information on CA practices and principles from available and reliable sources, including friends and family members, local extension personnel, other farmers who have used CA or books and publications in libraries and on the internet. Farmers should also identify possible sources of seeds for locally adapted cover crop species as well as the necessary tools and equipment for implementing NT systems. It is recommended that farmers start small, by partitioning off a small experimental plot having few agricultural limitations. Farmers are encouraged to be active learners in the process of establishing no-till conservation agriculture on their own farms, and over time and with careful observation and management practices, they may successfully adapt the new technologies to their own farming conditions. Try to find a farmer in your area who is already practicing CA and learn from him what is important for it to be successful. Once convinced a farmer can become the best extension agent to scale up adoption.

5. Are there increased pest and weed problems under CA?

   Enhanced weed and pest problems during the "transition phase" to CA is a major problem for many farmers and a significant obstacle to widespread farmer adoption. But this is also a major factor for farmers transitioning to organic agriculture. Weed and pest problems are biological symptoms of the change in ecosystem management under CA. Whereas farmers under conventional agriculture rely on tillage operations to help control many weeds and soil pathogens, farmers under CA must rely on alternative measures for weed and pest control. Some farmers respond by increasing applications of chemical herbicides, fungicides, and pesticides. Others prefer to use organically based products if available. Regardless of one's product preference, integrated weed, disease, and pest management approaches are recommended for a successful CA system. Crop rotations and permanent residue cover enhance biodiversity and are two mechanisms that help control weed, disease, and pest problems under CA. Thus, farmers typically report reduced levels of weed and pest problems under CA after a period of 4-5 years, or the time it takes for the system to achieve a new biological balance. This results in an overall decline in rates of application of agrochemicals under CA. In the rice-wheat systems of S. Asia, weeds are actually less in NT wheat after rice because the weed seed is not exposed if the soil is not disturbed. This was one of the reasons farmers adopted NT wheat in India. Interestingly, when a soil has increased, diversified microbial populations, the soil has the ability to keep soil pathogens in check.

6. Why should one consider adopting CA if adequate yields and profits are being realized using conventional practices?

   Conventional agriculture is not sustainable and there are many reports in the literature of declining yields and soil degradation using intensively tillage systems. This is due to higher rates of soil erosion and loss of soil organic matter (SOM), which results in greater Greenhouse gas emissions (GHG) and an increasing dependence on chemical fertilizers to make up for losses in soil fertility. Furthermore, the manufacture of chemical fertilizers and machinery for tillage under conventional agriculture require high quantities of nonrenewable fossil fuels and release of greenhouse gases (GHGs) into the atmosphere that are responsible for negative changes in climate. CA, by contrast, greatly reduces soil erosion and actually builds up soil organic matter reserves and soil fertility. Compared to conventional agriculture, CA uses fewer agrochemicals and greatly reduces fossil fuel consumption and greenhouse gas emissions. Yet for many farmers currently practicing CA, the increased profits they earn under CA are most attractive. This is because agricultural yields are maintained or increased under CA while decreasing both chemical, fuel and labor costs.

7. Doesn't conservation agriculture only work for growing grain crops?

   Although most of the area currently being cultivated under the rubric of conservation agriculture is devoted to the growing of basic grain crops such as maize, millet and wheat, CA has been successfully adapted to work for cultivating a wide variety of other crops such as soybean, groundnut, pigeonpea, sugar cane, potatoes, beets, cassava, other vegetables and legumes, and several perennial fruit and vine species. It is also being used for growing rice by replacing puddled soils and transplanting rice seedlings with direct sowing of rice seed even into no-tilled soil. The principles of minimal soil disturbance, permanent soil cover and rotations work for all crops. Note that a forest is essentially a CA system – no-till and residue cover from falling foliage.

8. Doesn't conservation agriculture only work for large-scale mechanized farms?

   This is a common misconception. The vast majority of farmers practicing no-till conservation agriculture are smallholder farmers from both developed and developing countries alike. These farmers rely on family or manual labor and animal traction as their primary energy inputs. CA technologies can use direct seeders/planters that have been successfully adapted to work with animal or manual labor as well as with modern farm machinery. Increasing farmer access to this equipment is critical for ensuring greater success in the field. Service providers of CA technologies can accomplish this by making their equipment more readily available to resource poor and small-scale farmers in developing countries on hire. Note also that there are examples of no-till being used in agriculture many centuries ago, like the 3-Sisters mound system by Iroquois Indians in North America, and the “Zai” pit system in Burkina Faso and many other countries.

9. Isn't tillage necessary for increasing water infiltration and soil aeration?

   Although decades of research have shown that conventional tillage operations are beneficial for loosening compacted soils and improving water infiltration, the long-term effect of tillage operations is exactly the opposite, as bulk densities increase, plow pans form and water infiltration rates decline. Conservation agriculture, on the other hand, increases soil organic matter (SOM) content and decreases surface runoff and compaction by maintaining year-round vegetative cover and reducing the number of passes made over fields. Higher SOM content also increases biological activity in soils, and soil biota soon overtake tillage functions (biological tillage) by increasing porosity, aggregate stability and soil structure created by soil biota like earthworms. Tillage also exposes the soil to raindrops that can disaggregate the soil and form a crust that reduces infiltration of water and air into the soil profile. Thus, both infiltration and aeration are higher under CA, as compared to conventional agriculture.

10. Are chemical herbicides necessary in order to control cover crops before planting primary food crops under conservation agriculture?

    The answer to this question depends on whom you talk to. Some proponents of CA believe that using chemical herbicides such as glyphosate represents the most cost-effective and least environmentally intrusive method of controlling cover crops under NT. Yet this is simply not an option for many organic growers and others who favor reducing the application of agrochemicals. Thus, new technologies for controlling cover crops through the well-timed mowing, rolling, or crimping of these crops prior to planting the main crop are being promoted as viable means of greatly reducing herbicide applications. In more temperate climates choosing a cover crop that is winter killed would work. There is also the tradeoff of using herbicides early on to get weeds under control and then easing off their use as the weeds are controlled by surface residues. Integrated weed management practices should also be encouraged for weed, but also pest and disease control. One component important in integrated management practices is also a component of CA; rotation of crops that can be a very effective way of controlling weeds.

11. Are nutrient losses higher under conservation agriculture?

    In some cases, nitrogen losses by volatilization are greater under CA since crop residues are left on the soil surface rather than incorporated into the soil. CA promotes the increase in surface soil microbes that will at first use nutrients in the residues and then release them to the plants later as they get recycled. However, if CA is used to establish leguminous cover crops, these systems usually experience a net gain in nitrogen since much of the nitrogen is "fixed" from the atmosphere rather than mined from the soil. Furthermore, phosphorus losses due to runoff is decreased under CA since the soil remains covered, infiltration is improved, erosion is decreased, and soil organic matter is increased. When applying chemical and organic fertilizers, animal manures and composts to soils under NT, these materials should be directly injected or band-applied in order to minimize nutrient losses without significantly disturbing the soil. Note that CA increases infiltration of water and so may increase leaching of nutrients, especially nitrogen, but CA increases SOM that can fix nutrients and so reduce leaching losses