Different Rates of N:P:K Fertilizer Effect on the Growth, Yield and Productivity of Component Crops in Upland Rice-Soybean Intercropping System

A two-year field experiment was carried out in the 2018 and 2019 cropping seasons to assess the effect of different rates of N:P:K (15:15:15) fertiliser on the growth, yield and productivity of component crops in upland rice-soybean intercrop in lowland humid region of Umudike, southeast Nigeria. The experiment was laid out in randomised complete block design (RCBD) with three replications. However, cropping system fertiliser rates were considered fixed during the statistical analysis to elicit more information on the effect of the cropping system in the study. The treatments include intercrop rice–soybean with five levels of N:P:K 15:15:15 at 0, 100, 200, 300 and 400 kg/ha fertiliser rates and sole upland rice and sole soybean each at the same rate. The results showed that the interaction of upland rice and soybean with N:P:K fertiliser significantly affected the plant height, number of leaves, leaf area index, weight of seeds per panicle, weight of seeds per plant and 1000 - seeds weight of upland rice. Based on the result of this investigation, it was observed that the cropping system and increased fertiliser rates positively affected the growth and yield component of upland rice and soybean. It was noted that the N:P:K fertiliser rate (400 kg) gave the highest growth and yield component of upland rice in the rice/soybean intercropping system. LER, as shown from the result, indicated that intercropped upland rice with 400 kg/ha N.P.K was highest in 2018, although the trend was not the same in 2019 as the gross monetary return.