Nitrogen and phosphorus uptake from isotope‐labeled fertilizers by sorghum and soil microorganisms

Abstract

On nutrient‐depleted Lixisols from Burkina Faso, nutrient acquisition by crops and soil microbes mainly relies on the limited amounts of mineral and organic fertilizers applied by small‐scale farmers. The objective of this study was to determine simultaneously the uptake of nitrogen (N) and phosphorus (P) contained in organic and mineral fertilizers by sorghum [Sorghum bicolor (L.) Moench ] and soil microbial biomass. Double 15N and 33P direct and indirect labeling techniques were applied in a pot experiment to determine the contributions of different fertilizers to sorghum N and P uptake during 52 d of growth. In parallel, soil respiration, available, and microbial N and P were tracked in an incubation experiment. Sorghum derived 83–90% of P from fertilizers. Nitrogen from cattle manure was poorly available, contributing only 20% of the N taken up by sorghum. Water‐soluble mineral fertilizers increased soil N and P availability, resulting in the highest total N and P uptake by sorghum from fertilizers and soil among all treatments. The application of cowpea [Vigna unguiculata (L.) Walp.] residues induced microbial N and P immobilization, reducing sorghum N and P uptake to the level of the non‐fertilized treatment. The use of double 15N and 33P labeling elucidated the impact of fertilizers on soil nutrient pools. The low plant N/P ratio suggested N limitation for sorghum in the manure treatment. Cowpea residues were inefficient for sorghum nutrition, but they increased soil microbial nutrient pools. This study gives insights on the potential effects of legume residues used as green manure to build soil fertility.

An isotope study on nitrogen and phosphorus use efficiency and movement in soil in a mimicked vermicompost‐based organo‐mineral fertilizer

“…The direct labeling technique allowed to calculate the plant N and P recovery from the fertilizers. To do so, first the frac-tion of total N and P in shoots derived from fertilizer (%Ndff or %Pdff) was calculated as shown in Equation ( 4), using the isotopic composition of the plant and fertilizer (Barraclough, 1995;Morel et al, 1989;Traoré et al, 2020). Thereafter, the uptake of N and P derived from fertilizer (Ndff, Pdff) was calculated as shown in Equation ( 5), using %Ndff or %Pdff and the total N and P uptake by the plant.…”

“…Therefore, accurate measurements of the soil‐crop system are necessary. Combined direct 15 N and 33 P labeling techniques in controlled conditions allow tracking accurately N and P uptake by plants from fertilizers (Bonvin et al., 2015; Traoré et al., 2020), while also studying nutrient mobility of the fertilizers in the soil that could give insights about nutrient immobilization and losses (Frick et al., 2022; Sørensen et al., 2023).…”

Effects of Nitrogen Addition on Rhizosphere Soil Microbial Community and Yield of Wheat in Loess Plateau

“…The improvement of element cycle and physical and chemical properties of soil ecosystem driven by microbial 7 is one of the methods to improve the yield and quality of cultivated crops. Nitrogen is the main factor for maintaining metabolic activity of microorganisms 8 . Similarly, functional microorganisms are also involved in soil nitrogen cycling.…”