Abstract:

To investigate the effects of biomass biochar particle size and application ratio on nitrogen and phosphorus loss in stony desertification farmland, and provide a theoretical basis for selecting and preparing soil conditioner and slow-release fertilizer carrier suitable for this area. In this experiment, rice husk biochar, rubber wood biochar, bamboo biochar with particle size of 0-1 mm (powdered biochar) and bamboo biochar with particle size of 1-3 mm (granular biochar) were selected, and four processing gradients (by carbon soil ratio of 1%, 3%, 5%) were set up for each biochar and non-biochar was taken as CK, 13 treatments in total, and the indoor pot and leaching experiments were carried out. The results showed that biomass biochar of different raw materials reduced the amount of infiltration water and soil nitrogen and phosphorus loss, and the effect on total nitrogen loss was better than that of total phosphorus loss. The water retention and nitrogen and phosphorus loss reduction of powdered bamboo biochar were better than that of granular biochar, the total nitrogen (TN) and total phosphorus (TP) loss reduction rates of powder bamboo biochar were 15.9%-26.1% and 8.9%-19.9%, respectively, and that of granular bamboo biochar were 5.1%-21.3% and 5.3%-14.3%, respectively. Except granular bamboo biochar whose application ratio of 3% was the best, and the application ratio of 5% was the best for all other biochar treatments. 5% rubber wood biochar treatment had the best effect on increasing the dry weight of ginseng fruit, water conservation and nitrogen and phosphorus loss reduction. Therefore, rubber wood biochar is the most suitable soil conditioner and slow release fertilizer carrier in Shilin stony desertification farmland area.

Key words: particle size, rice husk biochar, rubber wood biochar, bamboo biochar, stony desertification soil, nitrogen and phosphorus loss