Similar phosphorus transfer from cover crop residues and water-soluble mineral fertilizer to soils and a subsequent crop
Background and aims
Cover crops provide benefits in agricultural systems with high P availability (i.e., optimal or excessive soil P for plant growth) by reducing losses of soil phosphorus (P) via erosion and leaching, and potentially by increasing soil P availability when P is released during residue decomposition. We quantified P transfer from cover crop residues to soil pools and a subsequent wheat crop in a greenhouse experiment.
Soils from two field experiments in California (Davis and Salinas) were labeled with carrier-free 33P and amended at a rate of 15 mg P kg−1 soil with cover crop residues (rye, oat, fava bean, vetch, mustard, rye-legumes mixture) or water-soluble mineral fertilizer. We analyzed plants and several soil pools – resin, microbial, and organic – for P and 33P.
In both soils, residues and water-soluble mineral fertilizer had a similar effect on soil pools and wheat P uptake, except for higher microbial and organic P with residues in the Davis soil. Residues contributed 35–40 % (Davis) or 20–25 % (Salinas) of the P taken up by wheat, and 13–22 % (Davis) or 8–14 % (Salinas) of residue P was recovered in wheat.
Our results demonstrate that P taken up by cover crops can cycle rapidly in agricultural systems with high soil P availability, with direct benefits for soil P availability and few differences among these cover crop species.
KeywordsFava bean (Vicia faba) Purple vetch (Vicia benghalensis) Rye (Secale cereale) Oat (Avena sativa) Winter wheat (Triticum aestivum) White mustard (Sinapis alba)
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