An Approach to Improved Productivity on Deep Vertisols

Abstract

Large areas of deep Ver t i sol s in India ( e . g . , Madhya Pradesh, Maharashtra, and Andhra Pradesh) a r e fallowed during the rainy season and sown to crops dur ing the post rainy dry season to grow on residual moi s ture. Many of those who become aware of this landscape and tradi t ion have asked why these soils are not cropped dur - ing the rainy season itself. This quest ion is particularly appropriat e in those a r e a s where ear l y rains ar e reasonably dependable and the monsoon rainfall l s e ems sufficient to grow one or sometimes two crops . Although annual potent ial yields on the basis of water availability may be es t imated at 3-5 tonnes /ha, actual product ion in most of these regions is only 500-1000 kg/ha. The reasons for the t raditional practice of leaving mi l l ions of hectares of land fallow can be at tributed to the set t ement history and the special characteristics of these regions. Earlier , when the population densitieswer e low, systems of shifting agriculture were introduced; only pa r t of the total cultivable land was used for growing food crops , and after 2 or 3 ye a r s of cultivation these a r e a s wer e left to return to a bush fallow. Most of the time the natural canopy provided effective protect ion to the soil against erosion due to high intensity rains . When population and land p r e s - sur e increased, shifting cultivation was replaced by permanent , set t led agr icul ture.