Chickpea response to tillage and soil residual nitrogen in a continuous rotation with wheat: I. Biomass and seed yield

The present field study was undertaken in Córdoba (Spain) on a Vertisol to determine the effects of tillage systems on spring chickpea ( Cicer arietinum L.) yield over 12 years, and the effects of tillage systems and residual N on chickpea biomass, seed yield and yield components over 4 years, in a wheat ( Triticum aestivum L.)–chickpea rotation under rainfed Mediterranean conditions. Tillage treatments included no-tillage and conventional tillage. Nitrogen fertilizer rates were 0, 50, 100 and 150 kg N ha −1, applied only to wheat. Seed yield was strongly dependent on rainfall during the preceding fallow period, as well as during the flowering and seed-filling period. Maximum seed yield (about 2000 kg ha −1) was achieved with around 390 mm rainfall in those periods. Higher rainfall prompted lower seed yield, due to the negative effect of waterlogging. Although the tillage system did not significantly influence chickpea seed yield, no-tillage represents a viable alternative to conventional tillage. Application of fertilizer N to wheat at a rate of 100 kg N ha −1 consistently influenced subsequent chickpea seed yield due to the carryover effect of fertilizer N. Residual fertilizer N did not appear to affect chickpea N fixation, illustrating the inability of this legume to stock up with N. Biomass and harvest index were the two parameters most closely related to chickpea seed yield. Seeds per pod was the yield component exerting the greatest direct positive influence on seed yield. The compensatory effect of yield components on chickpea yield was very limited, since the indirect effects of these components were negligible.