An Ecological Research on Potential for Zero-growth of Chemical Fertilizer Use in Citrus Production in China

Overuse of chemical fertilizer has increased costs and damaged the agriculture ecological environment. Overuse of fertilizers in citrus (Citrus L.) orchards is becoming more serious in China. To understand the current status of farmer fertilization practice and the potential for fertilizer saving in citrus orchards in China would be meaningful for realizing the national policy of zero-growth in chemical fertilizer use. Therefore, the published literatures and statistical data were summarized to quantify the gap of citrus yield and fertilizer use efficiency among different countries, and to evaluate the potential for fertilizer saving in citrus production under different scenarios, and finally to suggest the strategies for both high yield and high efficiency of citrus production. The result showed that averaged citrus yield in China was 14.6 t/ha. Thus, the yield gaps, based on FAO data, were about 1.0 or 10 t/ha between China and the global averaged level or the average level of top 10 countries, respectively. On the other hand, the averaged rates of nitrogen (N), phosphorus (P) and potassium (K) fertilizer in orchards of major citrus producing regions of China were as high as 485,198 (P2O5), and 254 (K2O) kg/ha, respectively. Thus, partial factor productivity from applied N (PFPN) declined to 54.6 kg/kg in average which was only 30% of that in countries with advanced citrus industry such as USA, Brazil and South Africa. According to the domestic fertilization recommendation for citrus production in China, 62.0, 16.7 and 22.2 ten thousand tons will be saved for N, P and K fertilizer, respectively. This potential account 59.0%, 39.2% and 39.2% of estimated total amount of fertilizer used in citrus production in China. This fertilizer-saving potential can still work when the yield is projected to high yield level of 60 t/ha. In future, approaches including farmer training, moderate intensification, improvement of soil fertility, innovation of new-type fertilizers and methods for fertilizer application are needed to realize zero growth in chemical fertilizer use on citrus production in China or other similar countries.