Effects of nitrogen application and cassava–peanut intercropping patterns on crop yields and economic benefit

Objectives In order to provide a theoretical basis for rational intercropping of cassava with peanut and efficient use of nitrogen fertilizers, differences of crop yields and economic benefits were researched among cassava monocropping, peanut monocropping and different patterns of cassava intercropping with peanut, and the intercropping advantage and optimal model of cassava-peanut intercropping were revealed.

Methods In 2015 and 2016, an experiment with five planting patterns of cassava monocropping, peanut monocropping, one row of cassava intercropping with one, two and three rows of peanut, and two nitrogen levels of with no nitrogen application and with nitrogen application (180 kg/hm²) was conducted to study effects of nitrogen fertilization and different cassava-peanut intercropping on crop yields and economic benefits in the same row-spacing.

Results The yield, tuber root number per plant and fresh biomass of cassava were significantly increased by the nitrogen application. The peanut pod yield and biomass in the peanut monocropping were significantly increased by the nitrogen application, while those in the three intercropping patterns were significantly reduced. The total nitrogen accumulation of cassava, nitrogen accumulation of cassava at different stages in different intercropping patterns and total nitrogen accumulation in the peanut monocropping were significantly increased by the nitrogen application, but the total nitrogen accumulation of peanut in three intercropping patterns was reduced. The total output values and economic benefits in the five planting patterns were significantly improved by the nitrogen application. The fresh tuber root yields and total nitrogen accumulation of cassava in the three intercropping patterns were significantly lower than those in the cassava monocropping, the total nitrogen accumulation, pod yield and biomass of peanut were lower than those in the peanut monocropping, and the total output values and economic benefits were significantly higher than those in the cassava monocropping and the peanut monocropping. The order of total nitrogen accumulation from high to low in system was, the cassava intercropping with three rows peanut>cassava intercropping with two rows peanut>peanut monocropping>cassava intercropping with one row peanut >cassava monocropping. Input-output ratios in the three intercropping patterns were greater than that in the peanut monocropping, which was lower than that in the cassava monocropping. With the increase of peanut rows, the total nitrogen accumulation of cassava was decreased, the nitrogen accumulation amount, pod yield and biomass of peanut were increased significantly, the intercropping advantage and the land equivalent ratio were increased significantly, and total output and economic benefit were increased.

Conclusions Compared with the monocropping, the intercropping advantage of cassava intercropped with 2 rows and 3 rows of peanut was obvious, the economic benefits were improved significantly, the total nitrogen accumulation amounts in the system were increased significantly, and the land utilization rates were increased by 31%–62%.