Abstract:
There are many situations in the world that are not suitable for the implementation of no-till-based “conservation agriculture” (CA). These are mainly in marginal rainfed cropping areas in the hot, dry mid-latitudes. It is not possible to maintain the required levels of organic matter in the soil in these areas. Under no-till applied plant nutrients accumulate in the upper few centimeters of the soil, where they cannot really be exploited by plant roots. Liming to ameliorate acid soil conditions is ineffective, because the impact of the lime is confined to the upper few centimeters of the soil. Serious soil compaction, largely by means of wheel traffic, occurs close to the soil surface under no-till. Because roots are confined to soil above the compacted layer, they cannot exploit water stored in the soil below the compacted layer. This leads to poor yields due to drought stress. Compacted soil layers due to no-till predispose crop roots to infection by root rot diseases. It is essential to do a thorough evaluation of the land suitability of an area for no-till based CA before a decision is taken to implement it or not.
