施肥措施对复垦土壤团聚体碳氮含量和作物产量的影响

研究复垦后不同施肥措施下有机碳(OC)和全氮(TN)在水稳性团聚体及粉黏粒组分中的分布特征,以期深入理解不同施肥措施下土壤有机碳的固持机制。以生土和连续6年不同施肥措施的复垦土壤为研究对象,采集0～20 cm耕层土壤样品,利用湿筛法进行土壤粒径分组,分析大粒径大团聚体(> 2 mm)、小粒径大团聚体(>0.25～2 mm)、微团聚体(0.053～0.25 mm)和粉黏粒组分(<0.053 mm)中OC和TN含量,判断各粒径团聚体及粉黏粒组分中有机碳储量的驱动因素,探究团聚体及粉黏粒组分中有机碳含量与作物产量之间的关系。试验设不施肥(CK)、施氮磷钾化肥(NPK)、单施有机肥(M)和有机无机肥配施(MNPK)4个处理。结果表明:1)整个试验周期(2008—2013年),同CK相比,NPK、M以及MNPK处理均显著提高了玉米籽粒产量,且以MNPK处理的效果最显著,分别提高了79.49%、116.07%和113.85%。2)大团聚体和微团聚体中OC和TN含量相近,总体高于粉黏粒组分。同生土相比,CK、NPK和M处理均显著提高了>0.25～2、0.053～0.25 mm...

Effects of fertilization regimes on carbon and nitrogen contents of aggregates and maize yield in reclaimed soils

Abstract: This study aims to investigate the distribution characteristics of organic carbon (OC) and total nitrogen (TN) in water-stable aggregates, silt and clay fractions, in order to gain a deep understanding the sequestration mechanism of soil organic carbon (SOC) under various fertilization regimes. Topsoil samples (0-20 cm) were collected from the raw soil and reclaimed soil under different fertilization regimes of six consecutive ages. A wet sieving method was used to fractionate the particle size in soil, including the large macroaggregates (> 2 mm), small macroaggregates (0.25-2 mm), microaggregates (0.053-0.25 mm), as well as the silt- and clay-sized fractions (< 0.053 mm). The contents of OC and TN were analyzed for the water-stable aggregates, the silt and clay fractions. A systematic experiment was also carried out to reveal the driving factors for the changes of SOC storage, while, the relationship between crop yields and the OC content in the water-stable aggregates, the silt and clay fractions. Four treatments were selected, including no fertilizer (control, CK), nitrogen, phosphorus, and potassium fertilizer (NPK), single application of organic manure (M), and the combined application of organic manure and synthetic fertilizers (MNPK). The results showed that the contents of OC and TN were similar in macroaggregates and microaggregates, particularly higher than that in the silt and clay fractions. Compared with the raw soil, the CK, NPK and M treatments significantly increased the OC contents in the 0.25-2 mm, 0.053-0.25 mm aggregates, and the < 0.053 mm fractions, with the increase of 97.96%, 66.19% and 97.60% (CK), 87.07%, 92.09%, 92.80% (NPK), and 95.24%, 148.20%, 112.00% (M), respectively. The MNPK treatment significantly increased the OC contents in > 2, 0.25-2, 0.053-0.35 mm aggregates, and the < 0.053 mm fractions, with the increase of 151.88%, 160.54%, 135.25%, and 92.80%, respectively. In addition, the CK, NPK, M and MNPK treatments significantly increased the TN contents in > 2 mm, 0.25-2 mm and 0.053-0.25 mm aggregates, with the increase of 43.66%, 46.78%, and 29.95% (CK), 41.83%, 52.35%, 30.43% (NPK), 52.81%, 50.43%, 44.93% (M), and 63.80%, 62.96%, 39.61% (MNPK), respectively. The enrichment factors of organic carbon (EC) and total nitrogen (EN) were similar in the macroaggregates and microaggregates, generally higher than those in silt and clay fractions. Both the M and MNPK treatments significantly increased the C/N ratios of water-stable aggregates, and the silt and clay fractions (except for > 2 mm aggregates). The OC sequestrated in the > 2 mm aggregates was driven by the proportions of > 2 mm, whereas, the OC sequestrated in the other water-stable aggregates, and the silt and clay fractions was driven by the OC contents. The crop yields increased linearly as the increase of OC contents in the water-stable aggregates, and the silt and clay fractions, indicating that the SOC pool in this area has not saturated, especially for the < 0.053 mm fraction. Therefore, the application of organic manure combined with NPK (MNPK) to the reclaimed soil with low fertility can be an effective way to improve soil performance in coal mining subsidence areas.