Abstract:

Returning straw to the field is one of the effective ways of straw utilization. However, the amount of straw produced in the field is large and the degradation is slow. The addition of external materials is of great significance to accelerate the degradation of straw and promote the release of nutrients. Based on the mesh bag method, this study analyzed the effects of adding biochemical fulvic acid and microfiber rock wool on straw degradation, soil carbon, nitrogen nutrients and crop growth, and set up 3 gradients of external material input, including soil weight of 0.5%, 1%, and 2%, respectively. 7 treatments were conducted, namely, only straw (CK), straw+0.5% biochemical fulvic acid (T1), straw+1% biochemical fulvic acid (T2), straw+2% biochemical fulvic acid (T3), straw+0.5% microfiber rock wool (T4), straw+1% microfiber rock wool (T5), and straw+2% microfiber rock wool (T6). The results are as follows. (1) The straw degradation of each treatment with biochemical fulvic acid is slow in the first 100 days and then the degradation rate is faster; the degradation efficiency and degradation rate are inversely proportional to the concentration; after 360 days, the degradation rate reaches 75.97%-82.60%, and there is no significant difference among the treatments. The nitrogen release rate takes 100 days as the turning point; the nitrogen release rate of each treatment reaches 71.51%-74.75% at 360 days. Compared with CK, the treatments with biochemical fulvic acid could reduce soil bulk density by 19.85%-30.53%, increase soil total porosity by 19.57%-26.09%, and improve soil carbon and nitrogen content. Except T1 treatment, other treatments could inhibit crop growth. (2) Microfiber rock wool could accelerate the degradation of corn and release nitrogen rapidly (except T4) in all periods, reaching 63.60%-78.13% in 360 days. Compared with CK, the soil bulk density could be reduced by 24.43%-29.77%, the total soil porosity could be increased by 21.74%-26.09%, the soil carbon and nitrogen content are significantly increased, to effectively increase corn yield and promote root development. To a certain extent, both materials could accelerate straw degradation, promote nutrient release, and increase soil carbon and nitrogen content. The growth of crop is significantly influenced by the material concentration. The overall effect of adding microfiber rock wool is better than that of adding biochemical fulvic acid, with appropriate soil weight of 0.5%, 1%.

Key words: corn stalk degradation, biochemical fulvic acid, microfiber rock wool, nutrient release, crop growth