Zero (no) Tillage in the US Land Husbandry in Drought Prone areas: Msc. Module 556 Presented by Lemi Wani Jake

Definition Zero or No tillage system involves the direct placement of seeds without prior seed preparation. It is characterized by minimal soil disturbance and stubble or crop residue retention

History of Zero tillage No tillage was used in ancient times The Incas in the Andes practised no tillage In Brazil seeds were planted before tilling Also practised for centuries in Mexico and Central America In the US conservation tillage started in the 1930’s to alleviate wind erosion 1960: trials to kill weeds with Paraquat and to use Atrazine for residue control carried out.

History (cont) : no till demonstration farms established Kentucky farmers became first mechanized no tillage farmers 1966: Allis Chalmers designed the flutted coulter no tillage planter/seeder

History (cont) Area under no tillage in the US increased from 2.2 million ha in 1973 and 4.8 million in 1983 to nearly 20 million in Accounts for about 16% of the total cultivated area.

World Adoption

Table 1: Leading countries in the world countryArea (ha) Total area % USA Brazil Argentina7.332 Canada Australia1---- Paraguay0.7952

Benefits of No tillage Two characteristics give credit to no tillage: Stubble/residue retention and Minimal soil disturbance Stubble reduces impact of raindrop on soil, runoff and the rate of evaporation. By so doing it protects the soil from wind and water erosion and improves its water holding capacity.

Benefits of No tillage Water infiltration into the soil is also increased. Undisturbed soil and abundance of crop residue on the soil surface ensure high organic matter content in the soil. In no tillage, macro aggregates protect soil organic matter from microbial decomposition.

Benefits of no tillage Soil organic matter in turn encourages the formation of more soil aggregates Soil structure which increases soil porosity is improved in this way providing suitable conditions for plant growth Conventional tillage also encourages the formation of soil clods which are not stable due to destruction of its organic matter fig. 2

Benefits of no tillage With time the soil particles in these clods disperse and soil porosity is lost. Amount of organic matter is therefore higher in no tillage treatments than in conventional tillage treatments fig 3. Due to the high content of soil organic carbon in no tilled soils, they tend to have high proportions of stable soil macro-aggregates.

Fig 2.

Benefits of no tillage Fig.3 Soil organic carbon in various tillage systems. NT = No-till CT = Chisel-till MT = Mouldboard-till

Benefits of no tillage Soil organic carbon also increases the moisture retention capacity of the soil. The amount of moisture held in the soil determines the yield of a crop in dry weather In no tilled soils water losses by evaporation are minimised and more water is held in the soil due to its high organic matter content compared to conventionally tilled soils which have low organic carbon and high water losses by evaporation.

Benefits of no till Fertilizer use efficiency is ensured by the amount of water available in the soil. Nutrients in fertilizers are released in soluble form Adequate water in no till soils ensure nutrients availability to plants which absorb them. No till treatments therefore give higher yields than conventional treatments fig 4.

Benefits of No tillage Fig 4.Fertilizer use efficiency of various tillage systems.

Benefits of No-tillage Soil compaction is minimised in no-tillage because tractor passes once during sowing. In conventional tillage, however, weights of machinery and implements press soil particles together reducing the proportion of macro-pores in the soil. Soil aggregates break down and soil particles are closely packed together. The bulk densities of tilled soils are normally higher than those under no- tillage which are loose and encourage water infiltration. However, bulk density decrease in no till soils occur with time.

Benefits of No tillage No tillage increase microbial populations Plenty of food and less soil disturbance favour earth worms populations increase. Earth worms improve soil porosity and structure.

Corn growing on no-tilled soil

Benefits of No tillage Economics Machinery costs and labour costs are reduced: fuel, depreciation, interests, insurance, housing, maintenance, and time. Expenses are only related to fertilisers, herbicides, sowing and pesticides. In the USA no till has reduced costs of soybeans production by $ per acre fig 5.

Benefits of No tillage Fig.5.

Disadvantages of No tillage No tillage is risky Reports have shown decrease in crop yields in the long term A Kentucky report indicated decrease in corn yields under un-limed non-tilled soils compared to mouldboard tilled soils Low yields in this case are attributed to increased acidity due to build up of carbon and nitrogen near the soil surface resulting from stubble (crop residue).

Disadvantages of No tillage In Central Indiana yield losses were attributed to decline in soil fertility over a 12-year period. Improved water infiltration has apparently caused leaching of nutrients. In Central Minnesota there was a fall in corn yields despite fertilizer and lime treatment and application of herbicides and pesticides.

Disadvantages of No tillage It was established that soil type and bad climate are responsible for yield decline. Very low temperatures under the residue retard early growth in corn leading to lower harvest Also poorly drained soils reduces rate of growth resulting in poor yields fig 6.

Disadvantages of No tillage Fig 6: Yield decrease in No till system

Disadvantages of No tillage Weeds: –Tillage generally kills weeds –In no till soils weeds control is a problem –Requires timely applications of herbicides before and after sowing –Herbicides commonly used in no tillage includes: Gramoxone Extra, Atrazine, Bladex 4L, Dual 8E, Lasso 4E, 2,4-D Ester, 2,4-D Amine etc… –Rate of applications and timing are important to maximise yields.

Disadvantages of No tillage Pests and Diseases Crop residue on non-tilled soils encourage outbreaks of pests and diseases. This requires use of integrated pest management techniques such as choice of suitable rotations, residue management, pesticides application etc… Crop residue: interferes with sowing and causes a condition known as allelopathy Allelopathy is the toxic effect on a crop due to decaying residue from the same crop or similar species. Its effects are more likely to occur when corn is followed by corn in a rotation. Well-planned rotation and removal of residues using no-till planters is the solution.

Crop Rotation Effective management tool for no-tillage systems when well-planned Bulky crop residue more manageable by rotating cereals in alternation with legumes. Weeds can be easily controlled by herbicides- use of broadleaf herbicides to control broadleaf weeds in cereals. Lower risks of diseases and pests Rotation with forage crops like alfalfa

Conclusions No tillage is favoured due to its ability to conserve moisture and reduce soil erosion resulting in efficient water use and availability of nutrients Costs of production are also greatly reduced But is also risky involving factors that reduce yields. Proper integrated management techniques are required for it to succeed once the decision to adopt no tillage is taken. Several farmers in the US have gone no till faced by a number of challenges and realised its returns with time. To do this requires patience and sound management practices. No till can be adopted in many other areas after all ancient people practised no tillage farming alone.