Efficiency analysis and evaluation of centrifugal variable-rate fertilizer spreading based on real-time spectral information on rice

Abstract

Investigations regarding the use of centrifugal variable-rate fertilizer spreaders and their impact on agriculture production has become increasingly important for determining the effects and economic benefits of precision agriculture variable-rate fertilizer technology applied in the rice-and-wheat rotation areas of the middle and lower reaches of the Yangtze River in China. This study examines a self-developed centrifugal variable-rate fertilizer spreader based on real-time growth information of rice and wheat focusing on rice variety Nanjing 9108 as its research object. Field tests of variable-rate fertilizer application (compound fertilizer) were conducted in the Dongtai rice planting base, Jiangsu Province. Different areas were set up for artificial fertilizer spreading, traditional empirical balanced spreading, and real-time variable-rate spreading. The fertilizer application rates, rice growths, and yields of these fertilizer spreading methods for three consecutive years were compared and analyzed. Furthermore, the operational effectiveness of centrifugal variable-rate spreading was evaluated via partial budget analysis. The experimental results showed that the spreading application rate for the real-time variable-rate fertilization area decreased year by year by approximately 47.64 kg/hm2, whereas the application rate per unit area was reduced by approximately 15.88 %, compared with those for the traditional empirical balanced fertilization area. After the application of topdressing tillering fertilizer, rice growth in the real-time variable-rate fertilization area was better than in the others, whereas the spatial difference in its population structure was the lowest. There were differences in rice yield among the experimental areas: the average yield of the variable-rate fertilization area was 8996.70 kg/hm2, which was 5.93 % higher than that of the traditional empirical balanced fertilization area. According to the operational effectiveness analysis of real-time variable-rate fertilizer application in rice production, its fertilizer cost was only 504.72 RMB/hm2, whereas its yield profit was 17993.40 RMB/hm2. Thus, the fertilizer cost was reduced by 95.28 RMB/hm2, whereas the yield profit was increased by 1007.62 RMB/hm2, compared with those of the traditional empirical balanced fertilizer application. To sum up, this investigation verified that the newly developed centrifugal variable-rate fertilizer spreader, using real-time variable-rate fertilizer, can save on fertilizer and reduce its application, improve the population structure and spatial difference in crop growth, help increase crop yield and degree of balance, and produce economic, ecological, and social benefits. This study can provide a theoretical reference for promoting the pilot application of variable-rate fertilization technology in the rice-and-wheat rotation areas of the middle and lower reaches of the Yangtze River.