Continuous and pulse fertigation on the accumulation and export of nutrients by cowpea

-The objective was to evaluate the effects of pulse and continuous fertigation on the accumulation and export of nutrients by cowpea. The experimental design adopted was randomized blocks with 12 treatments distributed in a 5 x 2 + 2 factorial scheme, with four replicates, with five ETc replacement depths (40, 60, 80, 100 and 120%), combined with two types of fertigation application (pulse and continuous), plus two additional treatments under pulse (control 1) and continuous (control 2) irrigation with 100% ETc depth and conventional fertilization. The analyzed nutrients were N, P, K, Ca, Mg, S, Fe, Cu, Mn and Zn. Highest accumulations and exports of nutrients were obtained with pulse fertigation depths lower than 100% ETc. Conventional fertilization and pulse irrigation with 100% ETc depth promoted greater accumulation and export of nutrients compared to continuous irrigation. The descending order of nutrient accumulation for both types of fertigation application (pulse and continuous) was: N > K > Ca > P > Mg > S > Fe > Mn > Zn > Cu. The descending order of nutrient export by cowpea pods and grains was N > P > Ca > K > Mg > S > Fe > Zn > Mn > Cu for pulse fertigation and N > P > Ca > Mg > S > K > Fe > Zn > Mn > Cu for continuous fertigation.