[Construction effect of fertile cultivated layer in albic soil Ⅰ Effects of inversion tillage with organic mate-rials on the redistribution of organic matter in surface layer of albic soil].

Soil organic matter serves as a crucial indicator for soil quality. Albic soil, characterized by a barrier layer, exhibits limitations in organic matter content, which can adversely affect crop growth and development. To elucidate the impact of deep mixing of various organic materials on the redistribution of organic matter in the surface soil of albic soil could provide theoretical and technical insights for establishing suitable plough layers for albic soil in Northeast China. We conducted a two-year positioning experiment in Shuangyashan, Heilongjiang Province with five treatments, conventional shallow tillage (0-15 cm, CK), inversion tillage (0-35 cm) without or with straw return (T 35 and T 35 +S), inversion tillage with cattle manure (T 35 +M) and cattle manure plus maize straw (T 35 +S+M). The results showed that soil fertilization via deep mixing of organic materials to a depth of 35 cm significantly increased maize yield in albic soil, with the T 35 +S+M treatment demonstrating the most pronounced effect, yielding an average production of 2934.76 kg·hm -2 . Compared to CK, the T 35 treatment resulted in a significant 8.4% decrease in organic matter content in the tillage layer, a significant 7.6% increase in organic matter in the sub-tillage layer, and a relative richness degree of soil organic matter in the sub-tillage layer increased by 17.5%. Deep mixed return of organic materials following deep ploughing markedly increased organic matter content of the plough layer, with organic matter conversion ranging from 16.3% to 31.0%. In comparison to the T 35 treatment, there was no significant increase in soil organic matter content in the T 35 +S tillage layer and sub-tillage layer. Conversely, soil organic matter content increased by 4.6% and 6.9% in the T 35 +M and T 35 +S+M treatments, with corresponding increase of 11.2% and 15.4% in sub-tillage layer, respectively. Additionally, the soil organic matter richness index in sub-tillage layer increased by 2.5% and 5.1%, respectively. There was a significant positive correlation between organic matter content in the entire plough layer and maize yield, with a contribution rate of 17.5%. Therefore, the utilization of organic fertilizer or a combination of organic fertilizer and straw deep mixing can quickly fertilize albic soil by increasing soil organic matter content in both the whole tillage layer (0-35 cm) and the sub-tillage layer (15-35 cm).