论文部分内容阅读
本文研究了海河流域地区作物－土壤系统中作物氮素的输出归还量及土壤库存量。结果指出：不同作物氮的输出量和归还量差异很大，１５种作物中以谷子的输出量最大，每年达１１５１ｋｇ／ｈｍ￣２，水稻和莜麦最低，每年输出约３１和６．２ｋｇ／ｈｍ￣２。氮的归还量也以谷子最高，达６８．７３ｋｇ／ｈｍ￣２·ａ，向日葵最低，只２．７４ｋｇ／ｈｍ￣２·ａ。大部分作物都是输出量高于归还量。两者的比值不同作物有显著差异，大豆、棉花、谷子氮的输出量分别为归还量的２１、２０、１７倍，其余作物输出量一般为归还量的２－６倍，说明本区作物－土壤系统输出的氮素较多，归还的氮素较少。本区耕作土氮的平均库存量为１７４９．４３ｋｇ／ｈｍ￣２·ａ，以种植马铃薯、白菜、高粱的土壤的氮库存量较高，分别为３０３７．５、２０２７．０、２３１７．５ｋｇ／ｈｍ￣２·ａ；小麦土、芝麻土氮的库存量较低，只１１９２．５ｋｇ／ｈｍ￣２·ａ。不同作物土壤氮的库存量都高于作物的输出量，土壤氮的库存量为作物输出量的８倍。但作物从土壤中吸收的有效氮是有限的，必需通过施肥补充土壤因作物带走、氮挥发、淋失等被损失的氮。根据上述研究结果，提出维持本区作物－土壤系统氮素的平衡的意见，为本区合?
In this paper, the return of crop nitrogen and soil inventory in the crop-soil system in the Haihe River Basin were studied. The results showed that the output and return of nitrogen in different crops varied greatly. The output of millet in 15 kinds of crops was the highest, reaching 1151kg / hm ~ 2 each year and the lowest in rice and oatmeal. The annual output was about 31 and 6.2kg / hm ~ 2. The return of nitrogen is also the highest in millet, reaching 68.73kg / hm ~ 2 · a, the lowest sunflower, only 2.74kg / hm ~ 2 · a. Most of the crop output is higher than the return. The ratio of the two crops is significantly different, the output of soybean, cotton and millet nitrogen are respectively 21, 20 and 17 times of the restitution, and the rest of the crop output is generally 2-6 times of the restitution, indicating that crop- The soil system outputs more nitrogen and returns less nitrogen. The average nitrogen inventory of cultivated soil in this area was 1749.43kg / hm ~ 2 · a, so the nitrogen stocks of the soils planted in potatoes, cabbage and sorghum were higher, which were 3037.5, 2027.0 and 2317.5kg / hm ~ 2 · a; wheat soil, sesame soil nitrogen inventory is low, only 1192.5kg / hm ~ 2 · a. The amount of nitrogen in different crop soils was higher than crop output, and the amount of soil nitrogen stock was eight times the amount of crop output. However, the amount of available nitrogen absorbed by crops from the soil is limited. Fertilizers must be used to replenish the soil with nitrogen lost due to crop removal, nitrogen volatilization, leaching, and the like. Based on the above research results, we put forward the opinion of maintaining the balance of crop-soil system nitrogen in this area,