长期施肥条件下土壤养分的动态和平衡——Ⅰ对土壤腐殖质积累及其品质的影响

长期施用有机肥和化肥,对土壤腐殖质积累和改善品质的作用研究,于1986～1991在俄罗斯季米里亚捷夫农学院等地进行。主要结果如下:.1.有机肥对土壤腐殖质的积累作用大于NPK化肥。施肥所增加的土壤腐殖质,除了砂壤土外,主要是在0～60cm土层,60cm以下土层施肥效果不明显。.2.长期施用有机肥和NPK化肥,提高了胡敏酸组分Ⅰ(游离的及与活性R₂O₃结合态)的含量和腐殖酸相对迁移率,而与Ca⁺⁺离子结合的胡敏酸组分Ⅱ含量下降。由于胡敏酸组分Ⅱ与Ca⁺⁺离子结合减弱,增加了腐殖质在水中的溶解,使之在大雨或大量灌水时易于淋失。.3.施用有机肥和NPK化肥,水溶性腐殖物质的含量明显提高,缓解了干旱条件下土壤高浓度矿物盐的影响。.4.长期施肥提高了土壤的亲水性;其膨胀容积、膨胀速度常数、土壤吸水量、土壤表面积等指标均不同程度的提高,但砂壤土增加了幅度低于粉砂壤土和粘壤土。.5.胡敏酸甲氧基功能团的含量多寡是衡量土壤腐殖质化的重要指标。试验表明,长期施肥下低肥力酸性土壤中胡敏酸甲氧基含量提高了46％～300％,高肥力非酸性土壤提高了17％～32％。

DYNAMIC AND BALANCE OF SOIL NUTRIENTS UNDER LONG-TERM FERTILIZATION CONDITIONS I . Effects of fertilization on accumulation of soil humus and its qualities

Long- term trials of the effects of manure and chemical fertilizers on the accumulation of soil and its qualities were conducted in 1986~1991 in Russia and other places. The main results are as follow: 1.Application of manure has a better effect than NPK fertilizers on accumulation of soil humus. With the exception of sandy soil, the increase of soil humus was mainly in 0~60cm, and litter effect in lower layer. 2.Long-term application of manure and NFK fertilizers increased the content of component I of humus acid (free form and active R₂O₃ combined form) and the relative transport velocity, however, the content of component II of humus acid which combined with Ca²⁺ was decreased. The combination between component II of humus acid and Ca²⁺ declined, the dissolution of humus in water increased and the humus leached easily in the case of heavy rain or irrigation. 3.Application of manure and NPK fertilizers increased the content of soluble humus, and the adverse effect caused by high salinity on the crops under dry conditions could be reduced. 4.Long-term fertilization increased the hydrophilicity of soil, and the expansion volume, constant of expansion velocity, water absorbing capacity and the surface area of soil were also improved to a certain degree. The effects were less in the sandy loam soil than in silt loam and clay loam soil. 5.The content of methyl functional group of humus is an important index to evaluate the humification of soil. The experimental results showed that the content of methoxyl increased by 46%~300% in the acid soil with low fertility and by 17%~32% in the non-acid soil with high fertility under long-term fertilization condition.