基于农户施肥和土壤肥力的黑龙江水稻减肥潜力分析

Analysis of Fertilizer Application and Its Reduction Potential in Paddy Fields of Heilongjiang Province

【目的】黑龙江稻田面积320多万公顷,为全国稻田面积最大的省份,10多年来水稻产量一直徘徊在7000kg·hm^-2,也是我国稻田化肥用量(纯N约150kg·hm^-2)最低的省份。在化肥零增长的背景条件下,黑龙江是否存在节肥潜力有待研究。【方法】调查水稻主产区农户施肥情况。2005年调查区域为五常、方正、木兰、宁安、庆安、铁力、尚志、阿城;2008年调查区域为密山、虎林、庆安、五常、宁安、方正、萝北、桦川、富锦和尚志;2015年调查区域为五常、方正、宁安、虎林和庆安。每个地点随机选择一个乡,每个乡随机选择2或者3个村,每村调查10户,共638户。2009—2010年,采集了黑龙江水稻主产区8万多个土壤样品,测定0—20cm土层速效磷、速效钾养分含量。采用理论适宜施氮量法估算黑龙江稻田氮肥用量;依据作物养分需求量和稻田土壤养分状况,采用磷钾衡量监控方法,估算稻田磷、钾肥适宜施用量,在此基础上分析黑龙江省水稻减肥潜力。【结果】2005、2008和2015年黑龙江水稻平均产量分别为6427、7593和7142kg·hm^-2,3年平均产量为7104kg·hm^-2。农户间产量差异较大,高低相差近5000kg·hm^-2。稻田N、P2O5和K2O用量平均分别为141.0、56.6和51.6kg·hm^-2,N、P2O5和K2O用量高低相差均超过300kg·hm^-2,农户间施肥变异较大,盲目施肥问题突出。稻田土壤速效磷和速效钾的含量分别约为26和138mg·kg^-1。速效磷的变异超过了40%,不同区域间土壤肥力差异较大。70%以上的样品速效磷、速效钾含量处于较高水平。要达到7500kg·hm^-2的产量水平,对应的理论适宜N用量为105kg·hm^-2,只有20%的农户实现了高产氮素高效,有70%的农户具有节肥潜力,可以节氮超过26%。通过节肥,每千克氮素生产的粮食可由50kg提高到70kg。按照目前的产量和土壤养分状况,稻田P2O5和K2O适宜用量分别为41.6和35.9kg·hm^-2,可以减量约30%。调研农户中,具有节磷和节钾潜力的农户分别约占总体的71%和72%,处于低产低效的农户均占总体的30%,节肥潜力最大。【结论】黑龙江作为全国施肥量最低的省份,有约70%的农户处于高产不高效或者低产低效水平,过量施肥问题突出,节肥潜力20%以上。

【Objective】Heilongjiang has a paddy field of more than 3.2 million hectares, it is the largest province in China with rice fields. In the past ten years, rice production in Heilongjiang Province has been hovering at 7 000 kg·hm^-2, while it was the province with the lowest amount of fertilizer in paddy fields in China. Under the background of “fertilizer zero increase”, whether is there potential for fertilizer saving in Heilongjiang Province remains to be studied.【Method】We investigated paddy field fertilization across different farms in the main rice producing areas in Heilongjiang Province. In 2005, the survey areas were Wuchang, Fangzheng, Mulan, Ning'an, Qing'an, Tieli, Shangzhi and Acheng;in 2008, the survey areas were Mishan, Hulin, Qing'an, Wuchang, Ning'an, Fangzheng, Luobei, Huachuan, Fujin and Shangzhi;the survey areas in 2015 were Wuchang, Fangzheng, Ning'an, Hulin and Qing'an. From each county, a random township was selected, and 2 or 3 villages were randomly selected from each township, then 10 households were surveyed in each village. From 2009 to 2010, more than 80,000 soil samples from the main rice producing areas in Heilongjiang Province were collected, and the phosphorus and potassium nutrient contents in 0-20 cm soil layer were determined. The nitrogen application rate was estimated through theoretical appreciate application rate method. Based on the crop nutrient demand and the soil nutrient status of the paddy field, phosphorus and potassium application rate was evaluated. Fertilizer reduction potential was analyzed in Heilongjiang Province.【Result】According to the research data, the average rice yields in 2005, 2008 and 2015 were 6 427, 7 593 and 7 142 kg·hm^-2, respectively, and the average annual output was 7 104 kg·hm^-2. The crop yield differed between farms with a range of nearly 5 000 kg·hm^-2. The average amount of N, P2O5 and K2O in paddy fields were 141.0, 56.6 and 51.6 kg·hm^-2, respectively, and the difference in the amount of NPK fertilizers was more than 300 kg·hm^-2. Therefore, the results showed that fertilization variation among farmers was large, so the problem of blind fertilization was prominent. The content of available phosphorus and available potassium in the paddy soil of Heilongjiang Province were about 26 mg·kg^-1 and 138 mg·kg^-1, respectively. The variation of available phosphorus in soil exceeded 40%, and soil fertility varied greatly among different regions. High level phosphorus and potassium accounted for above 70% samples. To reach rice production levels of 7 500 kg·hm^-2, the theoretical suitable nitrogen application rate was 105 kg·hm^-2. Only 20% of farmers achieved high yield and high nitrogen efficiency, and 70% of the farmers had fertilizer-saving potential with nitrogen reduction of 26%. Through fertilizer saving, the grain produced per kilogram of nitrogen could be increased from 50 kg to 70 kg. According to the current yield and soil nutrient status, the appropriate amount of phosphate and potassium fertilizer in paddy fields was only 41.6 and 35.9 kg·hm^-2, which could be reduced by about 30%. Among the surveyed households, farmers whose fields had the potential for phosphorus and potassium-saving accounted for 71% and 72% of the total, respectively, among which the low-yield and low-efficiency farmers accounted for 30% of the total farmers, where the fertilizer-saving potential was the largest.【Conclusion】Although Heilongjiang was the province with the lowest fertilization rate in China, about 70% of farmers were high-yield but low efficiency, or low-yield and low efficiency, so the problem of excessive fertilization was prominent, and the fertilizer-saving potential was more than 20% in Heilongjiang Province.