Tillage minimum

Saprophytic, dark pigmented fungi such as Alternaria spp. can infect a wide range of plant species, especially tissues that are exposed to other biotic or abiotic stressors and older and senescing plant tissues. Also, wet weather conditions favour attack by Alternaria spp. Inoculum of Alternaria and potentially production of altemariol is further enhanced when cereal straw and stubble is left on the soil surface and not sufficiently incorporated into the soil after harvest (direct seeding and minimum tillage systems). 

In permanent crops such as apples, citrus fruits or olives, the risk of erosion is usually reduced by vegetation cover and minimum tillage with a low frequency in soil disturbance (Kabourakis 1996, Pajarbn et al. 1996). 

Phillips, W.M. (1969). Dryland sorghum production and weed control with minimum tillage. Weed Sci., 17 451-454. 

Paraquat, a bipyridyl quaternary ammonium salt, was introduced by ICI in 1965 (Fig. 3). It is a non-selective, contact herbicide on plant foliage, but is immediately inactivated when applied to soil. It is used in minimum tillage programs and as a postemergence directed spray in sugarcane and in fruit tree crops. 

Brazil accounts for 55% of pesticide sales in Central and South America. Pesticide sales in Brazil were US 1.4 billion in 1994 and an increase in sales was seen for all leading crops between 1993 and 1994 (up 57% for cotton, 44.8% for coffee, 36.3% for maize, 30.2% for soybean, 17.7% for citrus fruits and 11.5% for sugai cane). Herbicide sales dominate the market (50% in 1994) and it was predicted that usage would continue to expand as more farms convert to minimum tillage practices (due to severe problems with soil erosion and deterioration in soil structure) that rely on increased herbicide applications to control weeds,... 

The quick-growing catch and cover crops are also effective in erosion control. They can usually be seeded in the preceding crop, or perhaps by merely discing the soil, or using other minimum tillage procedures. If more extensive disturbance of the soil is made, erosion may proceed to such an extent that the benefits of the green crop are more than counteracted. 

The experimental results show that deep plowing of most reasonably normal soils does not have much effect on the depth to which roots penetrate. The depth of penetration does vary markedly with both soils and crops, but depth of plowing has a minor effect except where there is a very impervious layer. This fact is one of the main ones advanced by the advocates of no plowing or minimum tillage. 

The term minimum tillage has been defined as the fewest number of operations necessary to produce satisfactory yields. This system of growing crops does not refer to any very specific method of farming, but includes any or all practices that eliminate most of the disturbance of the soil and results in Uttle or no reduction in yields. 

Minimum tillage systems are of two general types those used in dry land farming and... 

The chief advantages usually realized from minimum tillage are that it (1) reduces compaction (2) lessens damage to soil aggregation and structure as cultivation is reduced ... 

Mulches are used primarily to increase water infiltration, reduce evaporation, modify soil temperatures, control weeds, prevent evaporation, and increase crop yields. They also increase the biological activities in the soil, modify the level of available nutrients, and help to maintain or increase the level of soil organic matter. Under conditions of no tillage, or minimum tillage of fine-textured soils, there is also likely to be a favorable effect on the physical conditions in the soil. These effects are discussed in the following pages. 

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