Smart Cover Crop Rotations: Agronomic Parameters and NK Efficiency Indices of Rice as Affected by Crop Rotations and N Applications Rates

Abstract

Continuous rice transplanting without crop rotation will reduce soil positive properties and crop productions in paddy field systems. Thus, the present study aimed to investigate the effect of cover crop rotations to enhance productivity and diminished chemical fertilizer application. The experiment was conducted as split plot based on a randomized complete blocks design with four replications in north of Iran, during 2015-16 and 2016-17. Six cover crop rotations including perko-rice, buko-rice, mixed cropping of clover + ramtil + phaselia-rice, clover-rice, faba bean-rice, and fallow-rice were used as main plots. Four levels of nitrogen fertilizer application included 0, 50, 100, and 150 kg.ha-1 of urea source as sub plots. The findings revealed that the maximum lodging index was achieved for perko-rice with 150 kg urea.ha-1 . Regarding the findings of yield components, the highest paddy yield (5147 kg.ha-1 ) was achieved in perko-rice rotation with 100 kg urea ha-1 . In all crop rotations, perko-rice rotation presenting the maximum N use efficiency, N utilization efficiency, and N uptake efficiency was obtained with 100 kg urea ha-1 . Totally, it was observed that the positive effects of the cover crops in the second year was were more pronounced, where perko was more suitable than other cover crops. These findings suggest that long-term cover of these crops especially perko and buko can improve soil properties and encourage proper plant growth in paddy fields rotation, which in the long term is useful for crop production and improving qualitative parameters.