1988－2018年中国水稻秸秆资源时空分布特征及还田替代化肥潜力

中国的水稻秸秆资源丰富,但不同地区水稻秸秆及养分资源量,还田替代化肥潜力以及随时间的变化特征尚不清楚。该研究基于农业农村部1988-2018年在全国稻作区的水稻土长期监测数据,分析了中国各地区不同年份的水稻秸秆和养分资源量及还田替代化肥潜力,为水稻秸秆资源的合理利用提供依据。结果表明:全国近10 a(2009-2018年)水稻秸秆和氮磷钾(NPK)养分资源年均量分别达到1.69×108t和452.09×104t,比1988-1998年增加0.23×108t和61.50×10~4t,东北增幅最高。全国水稻秸秆及养分资源随种植年限的延长呈增长趋势,第一阶段(1990s-2000s)和第二阶段(2000s-2010s)水稻秸秆资源年变化速率分别为18.11×104t/a和211.47×104t/a,N、P、K养分资源年变化速率分别为(0.15×10~4)、(0.02×10~4)、(0.31×104)t/a和(1.76×10~4)、(0.25×10~4)、(3.66×10~4)t/a。70%以上的水稻秸秆和养分资源分布在长三角、长江中游和西南,以长三角最高(4.15×107 t,NPK 111.05×104 t),华南最低(2.20×107 t,NPK 58.54×104 t)。30 a来,全国单位耕地面积水稻秸秆还田带入农田的氮(N)、磷(P)、钾(K)养分量持续稳定增加,占化肥年均施用量的比例为10.88%～12.53%、11.83%～17.13%、116.22%～122.62%。全国水稻秸秆还田的氮、磷、钾肥年均可替代量为(28.90±0.14)、(5.80±0.03)、(180.46±0.52)kg/hm~2,各区以长三角最高(N:(34.44±0.20)kg/hm~2、P:(6.91±0.04)kg/hm~2、K:(129.23±0.74)kg/hm~2),华南最低(N:(25.80±0.23)kg/hm~2、P:(5.18±0.05)kg/hm~2、K:(96.83±0.87)kg/hm~2)。充分利用水稻秸秆资源,是实现化肥减施增效的重要保障。

Temporal and spatial distribution characteristics of rice stalk resources and its potential of synthetic fertilizers substitution returning to farmland in China from 1988 to 2018

Rice stalk resource in China is plentiful, but in different regions the rice stalk resources, the corresponding nutrient resources and synthetic fertilizers substitute potential through rice stalk incorporation as well as the changes over time have not been very clear. Based on the long-term monitoring data of rice from 1988 to 2018 of the Ministry of Agriculture and Rural Affairs in China''s rice-growing areas, this study analyzed the amount of rice stalk and its nutrient resources and synthetic fertilizers substitute potential through rice stalk incorporation in different years in each region of China, aiming to provide basis for rational utilization of rice stalk resources. The results showed that the annual average amount of rice stalk resources and NPK resources reached 1.69×108 t and 452.09×104 t respectively during 2009-2018, which increased by 0.23×108 t and 61.50×104 t compared with 1988-1998, with the highest increase in North-East (NE). The annual average amount of rice stalk resources and NPK resources increased with planting years. In the first stage (1988-1998 to 1999-2008) and the second stage (1999-2008 to 2009-2018), the annual changing rate (ACR) of rice stalk resources were 18.11×104 t/a and 211.47×104 t/a, and the ACR of nutrient resources were 0.15×104 t/a of N, 0.02×104 t/a of P, 0.31×104 t/a of K and 1.76×104 t/a of N, 0.25×104 t/a of P, 3.66×104 t/a of K, respectively. There were more than 70% of rice stalk and its nutrient resources distributed in Yangtze River Delta (YRD), Middle of the Yangtze River (MYR) and South-west (SW), with the highest in YRD (4.15×107 t, 111.05×104 t of NPK) and the lowest in South China (SC) (2.20×107 t, 58.54×104 t of NPK). The rice stalk NPK nutrient returning to farmland per unit cultivated land area has increased continually during 1988-2018, accounting for 10.88%-12.53%, 11.83%-17.13%, 116.22%-122.62% of the annual fertilizer application, respectively. The annual average synthetic fertilizers substitution through rice stalk incorporation were 28.90±0.14 kg/hm2 of N, 5.80±0.03 kg/hm2 of P and 180.46±0.52 kg/hm2 of K in China, with the highest in YRD (34.44±0.20 kg/hm2 of N, 6.91±0.04 kg/hm2 of P, 129.23±0.74 kg/hm2 of K), and the lowest in SC (25.80±0.23 kg/hm2of N, 5.18±0.05 kg/hm2 of P and 96.83±0.87 kg/hm2 of K). Therefore, making full use of rice stalk resources could be an important guarantee for reducing fertilizer application and increasing fertilizer use efficiency.