Soil Aggregation and Nutrient Stoichiometry Affected by Fertilizations at Tea Plantations

Objective Aggregates distribution and nutrients stoichiometry of tea plantation soil under different fertilization modes were analyzed.

Method On field experimentation lots, treatments of no fertilization as control (CK) and, on furrows applying a chemical fertilizer (F), an organic fertilizer (OFG), a biofertilizer (OFWG) or half of the chemical fertilizer with other half of the organic fertilizer (OFF), as well as by broadcasting the organic fertilizer (OFS) or the biofertilizer (OFWS) were implemented. The resulting particle sizes of water-stable aggregates and nutrient stoichiometric characteristics of the tea garden soils were determined.

Result Among the various treatments on the soil, OFWG generated the most organic carbon at 31.77 g·kg⁻¹, and CK the least at 14.46 g·kg⁻¹; OFG the highest pH of 5.46, and F the lowest at 4.43; OFG the greatest proportion of aggregates particle size larger than 2 mm of 27.29%, and F the smallest of 4.20%; and OFF the highest percentage in ＜0.25 mm aggregates at 35.64 %, and OFWG the least at 25.38%. OFF significantly heightened the geometric mean diameter (GMD), mean weight diameter (MWD), and ＞2 mm water-stable aggregates proportions in soil under F, while significantly reduced the erodibility factor K. OFG and OFWG elevated the organic carbon, total nitrogen, total potassium, GMD, and MWD, whereas OFS and OFWG did to the total phosphorus. OFWG exerted the highest R_0.25 ratio of 74.62%. The RDA indicated the aggregates sized 2-1 mm and 1-0.5 mm and erodibility K to be the major indicators for soil fertility. The Pearson correlation analysis showed the content of 2-1 mm aggregates to significantly inversely correlate with that of organic carbon at P＜0.01, and with that of total nitrogen and ratio of carbon-potassium at P＜0.05.

Conclusion The application of organic or bio fertilizer on furrows at a tea plantation increased the contents of organic carbon, total nitrogen, and total potassium as well as promoted the formation of large aggregates, resulting in significantly improved structure and fertility of the soil.