期刊
COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS
卷 52, 期 20, 页码 2516-2532出版社
TAYLOR & FRANCIS INC
DOI: 10.1080/00103624.2021.1953051
关键词
Fulvic acid; humic acid; phosphorus; soil extracts; soil pore water
资金
- Dutch Ministry of Economic Affairs [WENR19]
Fertilization increased N and P uptake and grass yield, while the addition of FA or HA (200 mg C kg(-1) soil) had no effect regardless of the growth limiting nutrient. Nutrient availability was unaffected in soil porewater samples and 0.01 M CaCl2 soil extracts.
Humic substances are increasingly used as biostimulants in agriculture because of their supposed effects on nutrient uptake and crop yield. The objective of this study was to assess the effect of fulvic acid (FA) and humic acid (HA) addition with and without fertilization (N, P, K, S, and Ca) on (i) grass yield (Poa trivialis) and nutrient uptake and (ii) composition of soil porewater and 0.01 M CaCl2 soil extracts. Therefore, a pot experiment was performed using a loamy soil and a non-calcareous sandy soil. Fertilization increased N and P uptake and grass yield but there was no effect of FA or HA application (200 mg C kg(-1) soil) regardless of whether N or P was the growth limiting nutrient. Nutrient availability was assessed in soil pore water samples extracted by centrifugating moist soil and by 0.01 M CaCl2 extracts of ovendried soil. HA and FA had no effect on the availability of NO3 or ortho-P, neither in soil porewater nor in 0.01 M CaCl2 soil extracts. Fertilization led to an increase in 0.01 M CaCl2-extractable ortho-P but, remarkably, to a decrease in ortho-P and Dissolved Organic Carbon (DOC) concentrations in soil pore water samples. This discrepancy was explained by the higher ionic strength of pore water in the fertilized soils, which caused the pH to drop by 0.2 to 0.4 units and thereby stimulated adsorption of ortho-P and DOC to reactive soil minerals. Such salt-induced effects do not occur in 0.01 M CaCl2 soil extracts where the ionic strength is nearly constant.
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