Cover Cropping May Alter Legacy Phosphorus Dynamics Under Long-Term Fertilizer Addition

Abstract

Use of cover crops in an integrated agricultural system can reduce demand of inorganic phosphorus (P) fertilizers, where the subsequent crops can take up P accumulated in cover crops biomass after the decomposition. In this research we hypothesized that some cover crops can take up P from less labile fractions and recycle it back to the soil through plant residues resulting in better P use efficiency of the system; cover crops are capable of P uptake from subsurface layers which leads to the accumulation of this P on the surface after the decomposition of their residues; and cover crop species respond differently to distinct inorganic P sources. To examine these hypotheses, a field experiment was conducted over nine successive years in South Brazil. The experimental treatments were established as a split-plot randomized block design, in a 3 × 6 factorial scheme, considering three P treatments [no-P, single superphosphate (SSP), and rock phosphate (RP)] as main plot and six cover crop treatments (common vetch, white lupin, fodder radish, ryegrass, black oat, and a fallow) as subplots. Soil samples were collected from the depths of 0-5, 5-10, and 10-15 cm and analyzed by Hedley P fractionation. In P-unfertilized cropping system, the amounts of labile and mod-labile P fractions were not modified by cover crops related to fallow. When inorganic P fertilizers were applied, the amount of labile and mod-labile P pools under fallow were higher than under cover crops in 5-10 cm depth. Black oat and common vetch cycled more labile P under SSP and RP, respectively. Common vetch and ryegrass resulted in the highest accumulation of organic P on the surface under SSP and RP, respectively. Black oat was capable to change P extracted by 1.0 M HCl to more labile forms. Fodder radish showed the highest P uptake in comparison with other cover crops. The higher P balance efficiency of the system was achieved under SSP in comparison with RP application but it seems that cover crops are more effective at improving the efficiency under RP compared to SSP.

A Public-Private Partnership to Locate Fields for Implementation and Monitoring of Best Management Practices to Treat Legacy Phosphorus

“…The analysis of spatial field data and survey data provided by the agricultural retailers about the farmer and their operation revealed important information about the history of elevated-P fields and some characteristics that could influence the rate of P-loss. With cover crops, for example, studies have shown that P is moved from the subsurface to the surface soil layer which could explain why this practice was associated with elevated-P in our study (Soltangheisi et al, 2020). Alternatively, farmers who were concerned that P concentrations were too high in their fields may have been more likely to plant cover crops or engage in other conservation practices, leading to the positive correlation.…”

Trifolium subterraneum cover cropping for improving the nutritional status of a Mediterranean apricot orchard

“…In the last years the adoption of cover cropping has been proposed as a feasible alternative to the costly and environmentally harmful conventional agronomic management in specialized orchards of Mediterranean agroecosystems 14,16 . The present work represents a step forward by elucidating the effect of T. subterraneum cover crop on the nutritional status of apricot trees as compared to both spontaneous flora cover cropping and conventional management (as a control).…”

“…Therefore, the efforts of scientists are oriented for searching more sustainable management practices, aimed at enhancing yield and product quality of both herbaceous and arboreal crops, while at the same time optimizing the use of both external and internal chemical inputs 6–9 . In this framework, cover cropping (the mono‐ or inter‐cropping of herbaceous plants over either part of a year, or over an entire year) may provide important benefits to orchards, since it may reduce soil erosion and nutrient leaching, 10,11 keep the soil humidity at the proper level, 12 maintain soil fertility replenishing its organic matter, 13 enriching nitrogen (N) content (especially when leguminous cover crops are grown) 14 and releasing previously non‐available soil phosphorus (P) through the release of secondary metabolites into the rhizosphere 15,16 . In addition, cover crops also enhance soil microbial populations, encourage generalist predator arthropod populations and heartworm communities, and reduce pest and weed pressure 10,17,18 .…”

Unravelling the Role of Rhizosphere Microbiome and Root Traits in Organic Phosphorus Mobilization for Sustainable Phosphorus Fertilization. A Review

“…These species were able to mobilize labile and less labile Po and increase the proportion of Pi in the soil solution. Considering the literature on cover crop species, white lupine is widely suggested to be the most efficient for extracting Po and Pi forms and could be considered a P-mobilizing species, although this may depend on the characteristic of the organic input applied [209,210]. Furthermore, though there is little information available in the literature, it is also pointed out that cover crops could specifically increase the dissolution of resistant Po associated with fulvic acid and highly resistant Po associated with humic acid [211,212].…”