Yield production efficiencies as affected by nutrient management strategies under different rice cropping systems

Smart nutrient management strategies enhance rice yield while conserving resources. Nutrient Expert® (NE) was designed to offer fertilisation decision support for smallholders to improve productivity compared with farmers’ practice (FP) and commonly used soil testing-based management (ST). So far, NE-led yield increase in rice was analysed in terms of nutrient use efficiency. However, the crop physiological basis of the yield increase has not been investigated in detail, especially not in terms of the crucial parameter “radiation use efficiency (RUE)”. We analysed data from multi-location field experiments conducted in 2019 and 2020, varying in management of the cropping system and nutrient supply. Yield formation was dissected into components, consisting of the efficiency of intercepting incident radiation by the canopy ( ε i ), the efficiency of converting intercepted radiation into biomass ( ε c , or RUE), and the efficiency of partitioning biomass to grains ( ε p , or harvest index). Overall, season-long values of ε i with suitable fertilisation were in the range of 0.7–0.8; ε c ranged from 0.6 to 1.9 g MJ –1 , depending on soil nutrients, environmental conditions, and genotype. ε p values were in the range of 0.5 – 0.6. Despite higher ε i of FP due to the increase in N input, NE had a slight yield advantage, mainly attributed to the improved ε c and ε p . Across most rice cropping systems, correlations of yield were strongest with ε c , followed by the correlation with ε i , among the three efficiencies. We identified ε c as the major, and ε i as the second important, physiological parameter underlying the yield increase by NE-based nutrient management. This differs from the results of crop improvement during the Green Revolution when ε p primarily contributed to yield gain in major cereal crops. • Nutrient Expert for rice (NE) is a fertilisation decision support tool that boosts productivity. • We assessed radiation interception efficiency ε i , radiation conversion efficiency ε c , and biomass partitioning efficiency ε p . • The advantage of NE over other nutrient management strategies was mainly due to higher ε c . • Under current N management without (a)biotic stress, only ε c can be enhanced further.