Effect of some soil amendments on nutrients uptake and productivity of cowpea/maize intercropping system under water stress in sandy soil

A field experiment was conducted at the Ismailia Agricultural Research Station (ARC) in Egypt. To study the effect of three irrigation frequencies [2, 3 and 4 days], four soil application treatments [SN1 (100% NPK+ hydrogel), SN2 (75% NPK+ hyd.), SN3 (50% NPK+ hyd.), and SN4 (100% NPK without hydrogel as control)] on yields, nutrients content and uptake, land equivalent ratio (LER) and economic return of maize and cowpea. Maize components and maximum grain production as well as content and uptake of NPK were obtained with irrigation events once every 2 days (IF1) plus SN1, followed by irrigation once every 3 days (IF2) plus SN1. Also, the two most frequent irrigation frequencies (IF1 and IF2) plus SN2 improved the number of branches each plant and the yield of fresh fodder, with maximum values obtained by IF2. The NPK content, and NPK-uptake exhibited a similar forage yield trend. In contrast, the lowest values of all studied traits of both crops were obtained by less irrigation frequency (IF3) plus untreated soil with hydrogel (SN4). The highest LER (1.51) obtained by IF1x SN1 treatment, which at par with treatment IF2 x SN1 (1.50). Whereas highest values of net return was obtained with IF2 x SN1 compared to the other treatments. Thus, we can implement the irrigation maize/cowpea intercropping system once every 3 days with SN1(100% NPK +hydrogel) to reduce water frequency from 2 to 3 days and obtain higher productivity, nutrient content, LER, and maximum net income from intercropping maize and cowpea.