How fertile are semi-arid tropical soils?

摘要

The semi-arid tropical (SAT) regions are notably\udcharacterized by low rainfall and high temperatures,\udand hence low natural primary productivity and soil\udfertility. However, to adequately respond to the title of\udour article as to how fertile are SAT soils, there is a\udneed to critically review the current literature on the\udfertility status of SAT soils. Little attention has been\udpaid in the past to determining the fertility status of\udSAT soils supporting rainfed production systems despite\udthe fact that the SAT soils are relatively fragile\udthan their irrigated counterparts; and this is due to\udtheir widespread degradation and lack of investment\udin building up the fertility. However, as in the case of\udother agroecosystems, the soils in the SAT regions\udvary widely in various fertility parameters. For example,\udthe results of survey of large numbers of farmers’\udfields in the SAT regions of India, by the ICRISAT\udand its partners, showed that they vary widely in soil\udpH, salts (electrical conductivity, EC), organic C (an\udindex of available N) and major (N and P), secondary\ud(S) and micronutrients (B and Zn) although the soils\udwere low in organic C with widespread deficiencies of\udthese nutrients. From the results discussed in this\udarticle, it is concluded that in general, the soils in the SAT regions are low in fertility; however, they vary\udwidely in various fertility parameters.