黑土颗粒有机碳和氮含量对有机肥剂量响应的定量关系

黑土是一种非常重要的耕种土壤,但是由于过度地开发利用和水土流失导致土壤有机质含量迅速下降,严重影响了耕地生产力和作物产量。为了能够快速恢复黑土肥力,利用海伦国家野外科学观测研究站内的长期定位试验,定量分析了黑土颗粒有机碳和氮含量对有机肥剂量的响应。田间试验开始于2001年,设置了4个施肥处理,分别为:1单施化肥(OM0);2低剂量有机肥与化肥配施(OM1);3中剂量有机肥与化肥配施(OM2);4高剂量有机肥与化肥配施(OM3)。在2011年播种前,采集各处理0~20 cm耕层土壤样品。应用有机碳物理分组方法,测定分析了土壤有机碳、氮及各组分的含量。研究结果表明长期不同剂量有机肥输入能够显著增加黑土总有机碳和全氮含量(P0.05),每增施1 t有机肥,土壤有机碳含量增加0.186 kg,土壤全氮含量增加0.02 kg,表明增加有机肥投入量是提高黑土有机碳含量的有效措施。有机肥的施用增加了土壤中粗颗粒和细颗粒组分,不同剂量有机肥处理表现为OM3OM2OM1OM0,而减小了土壤中矿质结合态组分的含量;随着有机肥施入量的增加,粗颗粒和细颗粒土壤有机碳和氮的含量呈增加的趋势,而矿质结合态中的有机碳含量则略有下降,表明粗颗粒和细颗粒有机碳和氮是黑土有机碳和氮的主要储存库,有机无机配施对土壤有机碳、氮的提升作用主要集中于对活性组分颗粒有机质的形成和积累。与OM0处理相比,有机肥的施入显著降低了颗粒有机质和矿质结合态有机质的C/N,并且随着有机肥施入量的增加而逐渐降低。与单施化肥相比,化肥有机肥配施能够显著增加土壤的总有机碳,全氮,颗粒有机碳、氮含量,其中以化肥配施高剂量有机肥效果最佳,有利于黑土土壤肥力的快速提升,改善黑土的土壤质量。

Effect of Long-term Application of Organic Manure in Different Amounts on the Distribution of Particulate Organic Matter and the Contents of Carbon and Nitrogen in a Mollisol

The Mollisol is an important arable soil. A quickly decrease of organic matter in the Mollisol had limited the agricultural production and crop yields. The relationship between the input amount of organic manure application and the contents of carbon and nitrogen in soil particulate organic matter was investigated using soil samples from a long-term field experiment in National observation station of Hailun agro-ecology system to restore the soil fertility of a Mollisol. Soil samples from 0-20 cm layer were collected in four treatments including: chemical fertilizer (OM0), low amount organic manure (OM1), medium amount organic manure (OM2), high amount organic manure (OM3) set up in 2001. Physical fraction of organic carbon was used to test soil organic carbon, nitrogen and the contents of different fractions. Soil organic carbon and nitrogen were significantly increased by long-term organic manure application (P<0.05). Soil organic carbon and nitrogen contents were increased by 0.186 kg and 0.02 kg when organic manure application was increased by 1 t, respectively, indicating that increased organic manure was an effective practice for increasing organic carbon and nitrogen of the soil. Organic manure application enhanced coarse particulate and fine particulate fractions with the order of OM3>OM2>OM1>OM0, while mineral particulate fraction was decreased. Organic carbon and nitrogen contents in coarse particulate and fine particulate fractions were increased with the increasing organic manure application, suggesting that organic carbon and nitrogen in coarse particulate and fine particulate fractions were main storing form of soil organic carbon and nitrogen for the Mollisol. The impact of chemical fertilizer and organic manure application on soil organic carbon and nitrogen was attributed to the formation and transformation of active particulate fraction. The application of organic manure significantly reduced C/N ratios in particulate and mineral fractions with the order of OM1>OM2>OM3 compared with OM0. The combination of chemical fertilizer and organic manure significantly increased soil organic carbon and nitrogen in bulk soil, coarse particulate and fine particulate fractions compared with OM1. High amount of organic manure with chemical fertilizer application was the most effective practice to improve soil fertility and quality.