Abstract:
Objectives Single application of controlled-release urea fertilizer (CRU) is a scientific fertilization strategy that aligns with the practical needs of modern agricultural production in China. We studied the effectiveness of single application of CRU based on the Nutrient Expert (NE) recommendation scheme for various rice production systems across China.
Methods A total of 149 field experiments were conducted in the major production areas of early rice, middle-season rice, late rice, and single-season rice. Each experiment included seven treatments: NE recommended fertilization scheme (NE), farmers’ practice (FP), soil testing based fertilization scheme (ST), single application of CRU based on NE recommended fertilizer input amounts (NECRU); and the treatments of no nitrogen, no phosphorus, and no potassium, based on NE. At harvest, the rice straw and grain yields were recorded, plant samples were collected for determination of nutrient uptake, and fertilizer use efficiencies and apparent nutrient balances, as well as the economic returns were calculated.
Results Compared with the FP and ST treatments across the whole country on average, the NE treatment reduced input amount of N by 11.6% and 8.1%, P2O5 by 20.6% and 1.1%, and K2O by 30.8% and 17.4%, respectively. Compared with FP, ST, and NE treatments, the NECRU treatments increased rice grain yields by 740, 429, and 140 kg/hm2, respectively, and net economic returns by 2444, 1358, and 502 yuan/hm2; enhanced rice N uptake by 15.3%, 10.2%, and 2.9%, N uptake efficiency by 19.7%, 13.3%, and 2.5%, N recovery efficiency by 13.9, 10.0, and 2.8 percentage points, and N agronomic efficiency by 5.7, 3.8, and 1.0 kg/kg, respectively; increased rice P uptake by 10.1%, 7.1%, and 2.8%, P uptake efficiency by 37.7%, 15.3%, and 4.5%, P recovery efficiency by 13.4, 8.6, and 2.2 percentage points, and P agronomic efficiency by 11.4, 6.8, and 1.5 kg/kg, respectively; elevated rice K uptake by 9.6%, 5.9%, and 2.8%, K uptake efficiency by 142.8%, 118.7%, and 13.2%, K recovery efficiency by 21.3, 15.4, and 1.9 percentage points, and K agronomic efficiency by 8.1, 4.7, and 1.3 kg/kg, respectively. In addition, NECRU significantly reduced apparent nutrient surpluses. The apparent surpluses of N, P, and K decreased by 31.5%, 64.6%, and 51.7%, respectively, relative to FP, and decreased by 21.1%, 26.9%, and 33.6%, respectively, relative to ST.
Conclusions The integration of the Nutrient Expert recommendation for rice with controlled-release fertilizers enables the full exploitation of the advantages of the NE system, such as its simple and precise recommendations and wide applicability. Additionally, it facilitates one-time fertilization in China’s rice production, maintaining or even further enhancing rice yield and economic returns, and significantly reducing fertilizer nutrient surplus. It is thus suitable for promotion and application in smallholder rice farming systems across different ecological regions of China.