关键词: 施肥措施；秸秆；牛粪；黄泥田水稻土；团聚体组成；团聚体稳定性；养分分布；平均质量直径（MWD）, 几何平均直径（GMD）

Abstract: In order to find a suitable fertilization mode for low-fertility paddy soil, single application of chemical fertilizer ( NPK) was used as control, and the effects of long-term ( 8 years) different fertilization measures[chemical fertilizer combined with straw added straw fast-rot fungus (NPK+RS), controlled-release BB fertilizer combined with cow manure ( BBF+CM)] on aggregate composition,stability and nutrient distribution characteristics in yellow clayey paddy soil were studied.The results showed that compared with the soil nutrient conditions at the beginning of the experiment, the three fertilization treatments generally increased the soil organic matter,total nitrogen and available phosphorus contents in the cultivated layer,the most obvious effect was observed in the BBF +CM treatment,soil organic matter,total nitrogen and available phosphorus contents significantly increased by 41%,49% and 55% respectively. Compared with NPK treatment, NPK+RS and BBF+CM treatments increased the proportion of aggregates>2.00 mm in particle size and mean weight diameter( MWD) and geometric mean diameter(GMD),the improvement of BBF+CM treatment was slightly higher than that of NPK+RS treatment.In the three fertilization treatments, the rice rhizosphere soil aggregates MWD and GMD gradually increased with the progress of the rice growth period,while the non-rhizosphere soil aggregates MWD and GMD were generally the largest at the rice tillering stage and the smallest at the rice jointing stage.At the rice tillering stage, the non-rhizosphere soil aggregates MWD and GMD of the three fertilization treatments were larger than the rhizosphere soil;at the rice jointing stage and mature stage,the results were reversed. The results of variance analysis showed that rice sampling time, fertilization treatment and their interactions were the main factors affecting the stability of aggregates in yellow clayey paddy soil. The correlation analysis results showed that the stability of soil aggregates had significantly positive correlation with the content of soil organic matter,and significantly negative correlation with the content of available potassium. There were differences in the nutrient distribution of aggregates with different particle sizes. The organic matter and total nitrogen contents of>2.00 mm aggregates were higher,while the contents of available phosphorus and available potassium of<0.25 mm and 0.25—2.00 mm aggregates were higher. Compared with NPK treatment,NPK+RS and BBF+CM treatments could significantly increase the organic matter, total nitrogen, available phosphorus and available potassium contents of different sizes of aggregates.The organic matter, total nitrogen, available phosphorus and available potassium contents of different sizes of aggregates of NPK+RS treatment increased by 19%—23%,19%—29%, 26%—49% and 131%—157% respectively, and those of BBF+CM treatment increased by 23%—34%, 28%—81%, 47%—178% and 17%—41% respectively.In summary, both BBF+CM and NPK+RS fertilization modes could increase soil nutrient content,and improve soil structure in yellow clayey paddy. Among them,BBF+CM mode showed a larger positive effect,and could be used as an effective measure to improve soil productivity in low-yield yellow clayey paddy soil.

Key words: Fertilization measures, Straw, Cow manure, Yellow clayey paddy soil, Aggregate composition, Aggregate stability, Nutrient distribution, Mean weight diameter(MWD), Geometric mean diameter(GMD)