Effects of phosphorus activators on legacy phosphorus activation in vegetable soils and yield increases of cauliflower(磷素活化剂对菜地土壤遗留磷活化及花椰菜产量提升效果研究)

Abstract

To explore the effects of phosphorus activators on the activation of legacy phosphorus (P) in soils and cauliflower (Brassica oleracea var. botrytis) yields under reduced P fertilizer application, a field experiment was conducted with the cauliflower cultivar ‘Fuzhou 100 Days’ as the research object, and the activation effects of two P activators (biochar and alkali lignin) combined with inorganic fertilizers on legacy P in vegetable soils were analyzed. The results showed that both the biochar and alkali lignin treatments increased the soil pH values and P fertilizer agronomic efficiency, and promoted an increase in cauliflower yield. Compared with those under the treatment of the formula fertilization with reduced P fertilizer (SSNM), the cauliflower yield and plant total P content under the SSBC2 treatment (SSNM＋4 500 kg/hm2 biochar) increased by 17.43% and 9.63%, respectively, whereas those under the SSAL2 treatment (SSNM＋4 500 kg/hm2 alkali lignin) increased by 30.92% and 19.44%, respectively. Compared with biochar, alkali lignin significantly increased the abundance of P-function-related genes, particularly the phoD gene, in soils. Multiple linear regression analyses of the soil P contents of different fractions [moderately labile inorganic P (NaOH-Pi), P extracted by 1.0 mol/L HCl (dil.HCl-P), organic P extracted by concentrated HCl under heating (conc.HCl-Po), and residual-P] showed that these four indicators were the main factors contributing to P activators increasing the available P content. In conclusion, the application of biochar and alkali lignin can increase the soil available P content and P fertilizer agronomic efficiency, and the combination of formula fertilization with P activators can increase the cauliflower yield. In comparison with biochar, alkali lignin performs better in terms of improving the soil available P content, the abundance of P-function-related genes, cauliflower yield, plant total P content, and P fertilizer agronomic efficiency, with the effects increasing with the application rate. The above results have certain application value for optimizing the P fractions in vegetable soils, increasing vegetable yield per unit area, and reducing P fertilizer inputs.(为探究磷肥减施条件下，磷素活化剂对土壤遗留磷的活化效果及对花椰菜（Brassica oleracea var. botrytis）产量的影响，以花椰菜品种‘福州100天’为研究对象开展大田试验，分析生物质炭和碱木质素2种磷素活化剂配合无机肥料对菜地土壤遗留磷的活化作用。结果发现：生物质炭和碱木质素处理均能提高土壤的pH值和磷肥农学效率，促进花椰菜产量增加。与磷肥减施的配方施肥处理（SSNM）相比，SSBC2处理（SSNM＋4 500 kg/hm2生物质炭）的花椰菜产量和植株全磷含量分别增加17.43%和9.63%，SSAL2处理（SSNM＋4 500 kg/hm2碱木质素）的花椰菜产量和植株全磷含量分别增加30.92%和19.44%。碱木质素对土壤磷功能相关基因丰度的提升作用强于生物质炭，尤其是对phoD基因。对不同形态土壤磷[中等活性无机磷（NaOH-Pi）、1.0 mol/L HCl提取的磷（dil.HCl-P）、加热浓缩的HCl提取的有机磷（conc.HCl-Po）、残余磷]含量进行多元线性回归分析显示，这4个指标是磷素活化剂提升土壤有效磷含量的主要贡献因子。综上所述，生物质炭和碱木质素的应用可提高土壤有效磷含量及磷肥农学效率，且在配方施肥中添加磷素活化剂可增加花椰菜产量。其中，碱木质素在提升土壤有效磷含量、土壤磷功能相关基因丰度、花椰菜产量、植株全磷含量、磷肥农学效率方面的表现优于生物质炭，且效果随施用量增加而增加。本研究结果对优化菜地土壤磷素形态、提高蔬菜单产和减少磷肥投入具有一定的应用价值。