Availability and effect of fertilizer recommendation based on crop yield response for single-season rice in Northeast China

Objectives Fertilizer recommendation is the base of obtaining high yield and nutrient efficiency. The Nutrient Expert (NE), mainly based on crop yield response, is an effective and convenient fertilizer recommendation method. We studied its availability and effect in the single-season rice production in Northeast China.

Methods A total of 115 on-farm experiments were conducted in Heilongjiang and Jilin Provinces from 2013 to 2018. There were six fertilizer treatments in each experiment, in which the NPK fertilizer amount and ratio were designed with NE system (NE), farmers’ practices (FP), and conventional fertilizer recommendation based on soil testing (ST), and nitrogen, phosphorus and potassium omission treatments based on NE treatment were setup for the calculation of nutrient use efficiencies. The rice yield, total fertilizer cost and economic benefit were investigated at harvest of rice.

Results Although the differences in grain yields among NE, FP, and ST treatments did not reach significant levels (P = 0.185), NE treatment had an average yield of 9068 kg/hm², which was 344 kg/hm² and 196 kg/hm² higher than those of FP and ST, and the yield gaps with FP and ST was kept stable after the optimization of NE system. Despite of the highest total fertilizer cost (TFC), the gross return above fertilizer cost (GRF) in NE treatment was 1043 and 537 yuan/hm² higher than those in FP and ST treatments, partially due to the benefit derived from yield increases. All the recovery efficiencies (RE) of N, P and K fertilizers were the highest in NE treatment, and compared with FP and ST treatments, the RE increment for N were by 3.3 and 2.3 percentage points, for P by 3.5 and 3.6 percentage points, and for K by 7.3 and 4.6 percentage points. And the agronomy efficiencies of N and P fertilizers in NE treatment were significantly higher than those in FP treatment, with increment of 2.7 kg/kg for N (P = 0.022) and 4.1 kg/kg for P (P = 0.030), while agronomy efficiency for K did not increased significantly. Partial factor productivity (PFP) of fertilizer was negatively correlated with the amount of fertilizer application. PFP of N fertilizer in NE and ST treatments were significantly higher than those in FP treatment (P = 0.004), PFP of P fertilizer in ST treatment was significantly higher than those in NE and FP treatments (P = 0.001), while PFP of K fertilizer in FP treatment was higher than in NE and ST treatments, and reached significant level compared with NE treatment (P = 0.028).

Conclusions Using the NE fertilization recommendation system, similar or even higher grain yields and fertilizer efficiencies have been achieved compared with using the conventional fertilizer recommendation system in the large amount of field experiments in five years, which verifies the availability of the NE system in rice production. As the NE system can work with or without soil testing, it is a practical and promising fertilizer recommendation method in northeast rice growing-region.