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在钠质土(PH9.2,碱化度32)上,从1974年开始进行田间试验,12年(1974/75—1985/86)的水稻—小麦连续轮作,无肥区(对照)的有效N、P、K分别从初始水平的225,33.6和358公斤/公顷降至120,17.9和318公斤/公顷。连续单施氮肥(120公斤N/公顷)或配施P、K,可显著提高作物产量和土壤有效N。对轮作中水稻和小麦之一或二者均施用P22公斤/公顷,从1979年起水稻明显增产,而小麦仅1985/86年增产,且土壤有效P大量积累。单施N肥,有效P、K分别从初始水平33.6和358公斤/公顷降至8.7和280公斤/公顷。对两种作物或任一作物施用K42公斤/公顷,对产量无影响。施用N、P、K可增加作物体内这些元素的浓度和吸收量。12年连作使PH由9.2下降为8.5,碱化度由32下降力8.0,在这一点上各处理间无差异。
In the sodium soil (PH9.2, alkalinity 32), field experiments were carried out from 1974 onwards, and the paddy-wheat continuous rotation in 12 years (1974 / 75-1985 / 86) N, P and K dropped to 120, 17.9 and 318 kg / ha from the initial levels of 225, 33.6 and 358 kg / ha respectively. Continuous application of nitrogen fertilizer (120 kg N / ha) or with P and K significantly increased crop yield and soil available N. P22 kg / ha was applied to one or both of rice and wheat in the rotation, and rice production was significantly increased from 1979 onwards, while wheat increased only in 1985/86 and soil P was largely accumulated. The application of N fertilizer alone and the effective P and K decreased from initial levels of 33.6 and 358 kg / ha to 8.7 and 280 kg / ha, respectively. Application of K42 kg / ha to both crops or to any crop has no effect on yield. Applying N, P, K increases the concentration and uptake of these elements in the crop. 12-year continuous cropping reduced PH from 9.2 to 8.5 and basification from 8.0 to 8.0, with no difference between treatments at this point.