Effect Of Greenhouse Soil Management On Soil Aggregation In Northeast China

In solar greenhouses, agricultural practices may include frequent and intensive tillage and extensive use of fertilizers and pesticides. Tillage and fertilization disturbances can increase macroaggregate turnover, inhibit microaggregate formation within macroaggregates, and indirectly impair aggregate stability. This study aimed to investigate the effect of greenhouse soil management on soil aggregation and cementing agents in northeast China. This research provides a theoretical basis for continuous cropping obstacles perspective from improving soil structure. Main results for this study are as follows:The proportions of the different aggregate size classes were significantly affected by the tillage ages of greenhouse soils. The largest aggregate size class of dry sieve aggregate was >2 mm, of water stable aggregate was 0.25-0.053 mm and of microaggregate was 0.05-0.25 mm and 0.01-0.05 mm. The mass proportions of the>2 mm and<0.053 mmsize classes increased with increasing greenhouse ages. The opposite trend of 0.25-0.053 mm size class was also observed. The mass proportion of the 2-0.25 mm size class gradually but significantly decreased between the greenhouse ages of 0 and 5 years and increased afterwards. The short-term greenhouse soil management can improve the stability of microaggregate. Microaggregates (0.25-0.053 mm) may partially break down into silty clay particles (< 0.053 mm) with long-term greenhouse soil management.Short-term greenhouse management improved the decomposing of LF250, fPOM and imMPOM which combined with mineral substance to form MOM. Long-term greenhouse management improved the transformation of MOM into POM and the stability of 2-0.25 mm size class. Fep of 2-0.25 mm size class was partly aged into weak crystalline iron oxide. The same trends of hydroxy Al polymer in 0.25-0.053 mm size class and Feo in<0.053 mm size class were observed. Greenhouse soil management enhanced PO43". With the subsequent precipitation of Ca phosphate and Fe phosphate as cementing agents, stable microaggregates were promoted.Greenhouse soil management influenced the stability of micro-and macro-aggregate. From the point of microaggregate, it impacted the metabolism of POM in 0.25-0.053 mm size class, and restrained the stability of microaggregate. From another perspective of macroaggregate, it impacted the metabolisms of POM in 2-0.25 mm size class and MOM in 2-0.053 mm size class, and stability of macroaggregate. The effect of organic mineral complex on aggregate stability was being by means of loose combined Alp, Mnp and clay-Ca2+-organic matter.