Effects of Biostimulants and Fertilization on Nutrient Uptake by Grass and Composition of Soil Pore Water Versus 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 this study was to assess the effect fulvic acid (FA) humic (HA) addition with without fertilization (N, P, K, S, Ca) (i) grass yield (Poa trivialis) (ii) composition soil porewater 0.01 M CaCl2 extracts. Therefore, a pot experiment performed using loamy non-calcareous sandy soil. Fertilization increased N P but there no FA or HA application (200 mg C kg−1 soil) regardless whether growth limiting nutrient. Nutrient availability assessed pore water samples extracted by centrifugating moist extracts oven-dried had NO3 ortho-P, neither nor led an increase CaCl2-extractable ortho-P but, remarkably, decrease Dissolved Organic Carbon (DOC) concentrations samples. This discrepancy explained higher ionic strength fertilized soils, which caused pH drop 0.2 0.4 units thereby stimulated adsorption DOC reactive minerals. Such salt-induced do not occur where is nearly constant.