Impact des modes de gestion de la fertilité du sol et des systèmes de cultures sur la nutrition azotée et les rendements du mil (Pennisetum glaucum (L.) R. Br.) au Niger

Impact of Soil Fertility Management Practices and Cropping systems on Nitrogen Nutrition and Yields of Millet (Pennisetum glaucum (L.) R.Br.) in Niger. To identify the best methods of soil fertility management in Sahel conditions, the following objects were compared in a trial conducted according to a Latin square arrangement from 2011 to 2013 at Kalapaté (Niger) in three different millet-cowpea cropping systems (monoculture, intercropping, and rotation): (i) control without manure application, (ii) micro-dose of NPK (6 g of 15-15-15) per hole + 30 kg N ha-1, (iii) rock phosphates (30 kg ha-1 P2O5) + 30 kg N ha-1, (iv) phospho-compost (5 tones ha-1) + 30 kg N ha-1 and (iv) Super Simple phosphate (30 kg P2O5 ha-1) + 50 kg N ha-1. 15N isotope marked NPK and urea were used to assess the contribution of organic and mineral fertilization and of cowpea cultivation to the Nitrogen nutrition of millet. Millet yields of the treatments were significantly different from the control with yield increases ranging from 116 to 299%. Cowpea-millet rotation associated with these technologies led to a mean increase in grain yield of millet varying from 40 to 112% compared to monoculture. The use of the 15N isotope method evidenced the major role played by crop rotation in Nitrogen removal and uptake from the soil. The average Land Equivalent Ratio (LER) calculated from all compared crop associations amounts to 1.46. This indicates that it is more advantageous to practice intercropping than monoculture. Therefore these technologies improve agricultural productivity by enabling efficient use of land and better mobilization of soil nitrogen