Abstract
AimsAn essential task of agricultural systems is to improve internal phosphorus (P) recycling. Cover crops and tillage reduction can increase sustainability, but it is not known whether stimulation of the soil microbial community can increase the availability of soil organic P pools.MethodsIn a field experiment in southwest Germany, the effects of a winter cover crop mixture (vs. bare fallow) and no-till (vs. non-inversion tillage) on microbial P-cycling were assessed with soybean as the main crop. Microbial biomass, phospholipid fatty acids (PLFAs), P cycling enzymes, and carbon-substrate use capacity were linked for the first time with the lability of organic P pools measured by enzyme addition assays (using phosphodiesterase, non-phytase-phosphomonoesterase and fungal phytase).ResultsMicrobial phosphorus, phosphatase, and fatty acids increased under cover crops, indicating an enhanced potential for organic P cycling. Enzyme-stable organic P shifted towards enzyme-labile organic P pools. Effects of no-till were weaker, and a synergy with cover crops was not evident.ConclusionsIn this experiment, cover crops were able to increase the microbially mediated internal P cycling in a non-P-limited, temperate agroecosystems.
Highlights
Crop production depends on a sufficient supply of major nutrients such as phosphorus (P)
Of the Organic P (Porg) pool, on average 98 μg Porg g−1 were enzyme-labile, with cover crops increasing the amount of enzyme-labile Porg in October in comparison to bare fallow treatments (Fig. 2a and Table 1, Fig. 2 Soil P pools at Tachenhausen field site in 0–5 cm. a In the left figure, the top, middle and bottom bars correspond to inorganic P (Pi), enzyme-stable organic P (Porg) and enzyme-labile Porg, respectively; b The enzyme-labile P pool can be further subdivided into Porg hydrolysable for phosphodiesterase, nonphytase-phosphomonoesterase and fungal phytase
Phosphomonoesterase-labile P increased under cover crops in October (Fig. 2b and Table 1, Cover crop x Date p = 0.079)
Summary
Crop production depends on a sufficient supply of major nutrients such as phosphorus (P). Soil microbes affect the P nutrition of plants via antagonistic effects on plant pathogens (Finckh et al 2019), as well as production of phytohormones that modify both root growth and architecture (Hayat et al 2010). Among these microbes, arbuscular mycorrhizal fungi (AMF) are the most studied, and their abundance can be directly related to improved P nutrition for plants, especially in P-limited agroecosystems (Jansa et al 2011; Cozzolino et al 2013)
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