No-till farming
No-till farming is an agricultural technique for growing crops or pasture without disturbing the soil through tillage. No-till farming decreases the amount of soil erosion tillage causes in certain soils, especially in sandy and dry soils on sloping terrain. Other possible benefits include an increase in the amount of water that infiltrates into the soil, soil retention of organic matter, and nutrient cycling. These methods may increase the amount and variety of life in and on the soil. Typically, no-tillage systems require the use of very large amounts of herbicides to control weeds.
Tillage is dominant in agriculture today, but no-till methods may have success in some contexts. In some cases minimum tillage or "low-till" methods combine till and no-till methods. For example, some approaches may use shallow cultivation but no plowing or use strip tillage.
Background
is the agricultural preparation of soil by mechanical agitation, typically removing weeds established in the previous season. Tilling can create a flat seed bed or one that has formed areas, such as rows or raised beds, to enhance the growth of desired plants. It is an ancient technique with clear evidence of its use since at least 3000 B.C.No-till farming is not equivalent to conservation tillage or strip tillage. Conservation tillage is a group of practices that reduce the amount of tillage needed. No-till and strip tillage are both forms of conservation tillage. No-till is the practice of never tilling a field. Tilling every other year is called rotational tillage.
The effects of tillage can include soil compaction; loss of organic matter; degradation of soil aggregates; death or disruption of soil microbes and other organisms including mycorrhizae, arthropods, and earthworms; and soil erosion where topsoil is washed or blown away.
Origin
The idea of modern no-till farming started in the 1940s with Edward H. Faulkner, author of Plowman's Folly, but it wasn't until the development after WWII of powerful herbicides such as paraquat that various researchers and farmers started to try out the idea. The first adopters of no-till include Klingman, Edward Faulkner, L.A. Porter, Harry and Lawrence Young, the Instituto de Pesquisas Agropecuarias Meridional with Herbert Bartz.Adoption in the United States
No-till farming is widely used in the United States and the number of acres managed in this way continues to grow. This growth is supported by a decrease in costs. No-till management results in fewer passes with equipment, and the crop residue prevents evaporation of rainfall and increases water infiltration into the soil.Issues
Profit, economics, yield
Some studies have found that no-till farming can be more profitable in some cases.In some cases it may reduce labour, fuel, irrigation and machinery costs. No-till can increase yield because of higher water infiltration and storage capacity, and less erosion. Another possible benefit is that because of the higher water content, instead of leaving a field fallow it can make economic sense to plant another crop instead.
A problem of no-till farming is that in spring, the soil both warms and dries more slowly, which may delay planting. Harvest can thus occur later than in a conventionally tilled field. The slower warming is due to crop residue being a lighter color than the soil which would be exposed in conventional tillage, which then absorbs less solar energy. This can be managed by using row cleaners on a planter.
Costs and management
No-till farming requires some different skills than conventional farming. A combination of technique, equipment, pesticides, crop rotation, fertilization, and irrigation have to be used for local conditions.Equipment
On some crops, like continuous no-till corn, the thickness of the residue on the surface of the field can become a problem without proper preparation and/or equipment. No-till farming requires specialized seeding equipment, such as heavier seed drills to penetrate through the residue. Ploughing requires more powerful tractors, so tractors can be smaller with no-tillage. Costs can be offset by selling ploughs and tractors, but farmers often keep their old equipment while trying out no-till farming. This results in a higher investment into equipment.Drainage
If a soil has poor drainage, it may need expensive drainage tiles or other devices to remove excess water under no-till. Water infiltration improves after 5–8 years of no-till farming.Increased herbicide use
One of the purposes of tilling is to remove weeds. No-till farming changes weed composition: faster growing weeds may be reduced as increased competition with eventual growth of perennials, shrubs and trees. This problem is usually solved with a herbicide such as glyphosate in lieu of tillage for seedbed preparation, so no-tillage often uses more pesticides in comparison to conventional tillage. Some alternatives can be winter cover crops, soil solarization or burning. However the use of herbicides is not strictly necessary, as demonstrated by Masanobu Fukuoka.No-till occasionally uses cover crops to help control weeds and increase organic residue in the soil. Cover crops then need to be killed so that the newly planted crops can get enough light, water, nutrients, etc. This can be done by rollers, crimpers, choppers and other ways. The residue is then planted through, and left as a mulch. Cover crops typically must be crimped when they enter the flowering stage.
With no-till farming, residue from the previous years crops lie on the surface of the field, which can cause different, greater, or more frequent disease or weed problems compared to tillage farming.
Fertilizer
One of the most common yield reducers is nitrogen being immobilized in the crop residue, which can take a few months to several years to decompose, depending on the crop's C to N ratio and the local environment. Fertilizer needs to be applied at a higher rate. An innovative solution to this problem is to integrate animal husbandry in various ways to aid in decomposition. After a transition period the soil may build up in organic matter. Nutrients in the organic matter are eventually released into the soil..Environmental
Greenhouse gases
According to one 2003 study agriculture has released an estimated 78 billion metric tons of carbon in the last few centuries. No-till farming has been claimed to increase soil organic matter, and thus increase carbon sequestration. While many studies report soil organic carbon increases in no-till systems, others conclude that these effects may not be observed in all systems, depending on factors, such as climate and topsoil carbon content. However, there is debate over whether the increased sequestration sometimes detected is actually occurring, or is due to flawed testing methods or other factors. There is evidence that no-till systems sequester less carbon than conventional tillage. A 2014 study concluded that this occurs because the “no-till subsurface layer is often losing more soil organic carbon stock over time than is gained in the surface layer.” Also, there has not been a uniform definition of soil organic carbon sequestration among researchers. The study concludes, "Additional investments in soil organic carbon research is needed to better understand the agricultural management practices that are most likely to sequester SOC or at least retain more net SOC stocks."No-till farming reduces nitrous oxide emissions by 40-70%, depending on rotation. Nitrous oxide is a potent greenhouse gas, 300 times stronger than CO2, and stays in the atmosphere for 120 years.
Soil
No-till farming improves aggregates and reduces erosion. Soil erosion might be reduced almost to soil production rates.Research from over 19 years of tillage studies at the United States Department of Agriculture Agricultural Research Service found that no-till farming makes soil less erodible than ploughed soil in areas of the Great Plains. The first inch of no-till soil contains more aggregates and is two to seven times less vulnerable than that of ploughed soil. More organic matter in this layer is thought to help hold soil particles together.
No ploughing also means less airborne dust.
Water
No-till farming improves water retention: crop residues helps water from natural precipitation and irrigation to infiltrate the soil. Residue limits evaporation, conserving water. Evaporation from tilling reduces the amount of water by around 1/3 to 3/4 inches per pass.Gully formation can cause soil erosion in some crops such as soybeans with no-tillage, although models of other crops under no-tillage show less erosion than conventional tillage. Grass waterways can be a solution. Any gullies that form in fields not being tilled get deeper each year instead of being smoothed out by regular plowing.
A problem in some fields is water saturation in soils. Switching to no-till farming may increase drainage because soil under continuous no-till include a higher water infiltration rate.