Effects of fish protein fertilizer on soil properties, bamboo growth and bamboo shoot yield of Lei bamboo (Phyllostachys violascensʻPrevernalisʼ) forest

Abstract Lei bamboo (Phyllostachys violascensʻPrevernalisʼ) is a high economic value species with high yield and good quality of bamboo shoots. However, heavy chemical fertilizer and covering cultivation are used to produce off-season bamboo shoots, resulting in soil degradation and a decline in soil productivity. This study introduced an amino acid fertilizer called fish protein fertilizer to replace part of chemical fertilizer, and investigated the effect of different fertilizer combinations on bamboo growth, shoot yield and soil properties to clarify the growth-promoting mechanism of amino acid fertilizer. Results showed that after replacing 45 kg of compound fertilizer with 10 kg or 20 kg of fish protein fertilizer (1) bamboo shoot yield increased by 23.24% or 26.19%, respectively; (2) growth of leaves and roots were enhanced, thick root proportion increased, and proportion of root in the topsoil layer decreased; (3) soil pH, contents of AP (available phosphate), SOC (soil organic carbon), MBC (microbial biomass carbon) and MBN (microbial biomass nitrogen), soil enzyme activity increased; (4) contents of N and P in leaf increased, while the N/P and K/P decreased. Overall, amino acid fertilizer can promote microbial growth and improve soil enzyme activity through supplying carbon sources and nitrogen sources, thus promoting phosphorus activation and increasing soil phosphorus effectiveness, and then improving the foraging scale of root systems, and ultimately enhancing nutrients absorption and increasing bamboo shoot yield.