Soil phosphorus mobilization in the rhizosphere of cover crops has little effect on phosphorus cycling in California agricultural soils

Abstract. The goal of this study is to clarify research needs and identify effective actions for enhancing soil health. This was done by a synopsis of soil literature that specifically tests actions designed to maintain or enhance elements of soil health. Using an expert panel of soil scientists and practitioners, we then assessed the evidence in the soil synopsis to highlight actions beneficial to soil health, actions considered detrimental, and actions that need further investigation. Only seven of the 27 reviewed actions were considered to be beneficial, or likely to be beneficial in enhancing soil health. These included the use of a mixture of organic and inorganic soil amendments, cover crops, crop rotations, and growth of crops between crop rows or underneath the main crop, and the use of formulated chemical compounds (such as nitrification inhibitors), the control of traffic and traffic timing, and reducing grazing intensity. Using a partial Spearman's correlation to analyse the panel's responses, we found that increased certainty in scientific evidence led to actions being considered to be more effective due to them being empirically justified. This suggests that for actions to be considered effective and put into practice, a substantial body of research is needed to support the effectiveness of the action. This is further supported by the high proportion of actions (33 %), such as changing the timing of ploughing or amending the soil with crops grown as green manures, that experts felt had unknown effectiveness, usually due to insufficient robust evidence. Our assessment, which uses the Delphi technique, increasingly used to improve decision-making in conservation and agricultural policy, identified actions that can be put into practice to benefit soil health. Moreover, it has enabled us to identify actions that need further research, and a need for increased communication between researchers, policy-makers and practitioners, in order to find effective means of enhancing soil health.

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Soil phosphorus cycling in an Antarctic polar desert

Geoderma ◽

10.1016/j.geoderma.2007.10.007 ◽

2008 ◽

Vol 144 (1-2) ◽

pp. 21-31 ◽

Cited By ~ 23

Author(s):

D.B. Bate ◽

J.E. Barrett ◽

M.A. Poage ◽

R.A. Virginia

Keyword(s):

Soil Phosphorus ◽

Phosphorus Cycling ◽

Polar Desert

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Combinations of cover crop mixtures and bio-waste composts enhance biomass production and nutrients accumulation: a greenhouse study

Renewable Agriculture and Food Systems ◽

10.1017/s1742170515000423 ◽

2015 ◽

Vol 31 (6) ◽

pp. 507-515 ◽

Cited By ~ 6

Author(s):

Aime Jean Messiga ◽

Mehdi Sharifi ◽

Sheena Munroe

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Agricultural Soils ◽

N Uptake ◽

P Uptake ◽

N Fertilization ◽

K Uptake ◽

Soil P ◽

Greenhouse Study ◽

Synthetic Fertilizer

AbstractImproved farming practices are needed to produce more food in a sustainable way. This study assessed 12 combinations of cover crop mixtures and amendment treatments and their effects on shoot and root dry (matter (DM) weights, nitrogen (N), phosphorus (P) and potassium (K) uptakes in plants, Mehlich-3 extractable P (PM3) and K (KM3). Shoot and root DM weights were increased by 30–63% with combinations of clover-based cover crop mixtures and 65 Mg ha−1of municipal solid food waste (MSFW) compared with synthetic fertilizer. The combination of clover-based cover crop mixtures with MSFW increased N uptake by 38 and 30%, P uptake by 57 and 40% and K uptake by 77 and 77% compared with fertilized and unfertilized treatments, respectively. The combination of vetch-based cover crop mixtures with MSFW had no effect on N uptake, but increased P uptake on average by 43%, and K uptake on average by 11% compared with fertilized and unfertilized treatments. The highest soil PM3and KM3values were obtained with additions of MSFW, while the lowest were obtained with synthetic fertilizer indicating that the amount of P and K added with MSFW were greater than cover crop needs. Combining cover crop mixtures and MSFW at levels recommended for N fertilization allows meeting cover crops’ nutrient needs and increases biomass inputs to agricultural soils, but long-term monitoring of soil P is required to limit potential P build-up.

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Soil controls of phosphorus in runoff: Management barriers and opportunities

Canadian Journal of Soil Science ◽

10.4141/cjss09106 ◽

2011 ◽

Vol 91 (3) ◽

pp. 329-338 ◽

Cited By ~ 97

Author(s):

Peter Kleinman ◽

Andrew Sharpley ◽

Anthony Buda ◽

Richard McDowell ◽

Arthur Allen

Keyword(s):

Water Quality ◽

Surface Waters ◽

Agricultural Soils ◽

Soil Phosphorus ◽

Short Term ◽

Runoff Water ◽

Sediment Delivery ◽

Persistent Problem ◽

Soil P ◽

Barriers And Opportunities

Kleinman, P. J. A., Sharpley, A. N., Budda, A. R., McDowell, R. W. and Allen, A. L. 2011. Soil controls of phosphorus in runoff: Management barriers and opportunities. Can. J. Soil Sci. 91: 329–338. The persistent problem of eutrophication, the biological enrichment of surface waters, has produced a vast literature on soil phosphorus (P) effects on runoff water quality. This paper considers the mechanisms controlling soil P transfers from agricultural soils to runoff waters, and the management of these transfers. Historical emphases on soil conservation and control of sediment delivery to surface waters have demonstrated that comprehensive strategies to mitigate sediment-bound P transfer can produce long-term water quality improvements at a watershed scale. Less responsive are dissolved P releases from soils that have historically received P applications in excess of crop requirements. While halting further P applications to such soils may prevent dissolved P losses from growing, the desorption of P from soils that is derived from historical inputs, termed here as “legacy P”, can persist for long periods of time. Articulating the role of legacy P in delaying the response of watersheds to remedial programs requires more work, delivering the difficult message that yesterday's sinks of P may be today's sources. Even legacy sources of P that occur in low concentration relative to agronomic requirement can support significant loads of P in runoff under the right hydrologic conditions. Strategies that take advantage of the capacity of soils to buffer dissolved P losses, such as periodic tillage to diminish severe vertical stratification of P in no-till soils, offer short-term solutions to mitigating P losses. In some cases, more aggressive strategies are required to mitigate both short-term and legacy P losses.

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Reviews and Syntheses: Ironing Out Wrinkles in the Soil Phosphorus Cycling Paradigm

10.5194/bg-2020-130 ◽

2020 ◽

Author(s):

Curt A. McConnell ◽

Jason P. Kaye ◽

Armen R. Kemanian

Keyword(s):

Soil Phosphorus ◽

Phosphorus Cycling ◽

Organic P ◽

New Techniques ◽

Inorganic P ◽

Soil P ◽

Plant System ◽

P Sorption ◽

P Cycling ◽

Critical Challenge

Abstract. Soil phosphorus (P) management remains a critical challenge for agriculture worldwide, and yet we are still unable to predict soil P dynamics as confidently as that of carbon (C) or nitrogen (N). This is due to both the complexity of inorganic P (Pi) and organic P (Po) cycling and the methodological constraints that have limited our ability to trace P dynamics in the soil-plant system. In this review we describe the challenges to building parsimonious, accurate, and useful P models and to explore the potential of some new techniques to advance modeling efforts. To advance our understanding and modeling of P biogeochemistry, research efforts should focus on the following: 1) update the McGill and Cole (1981) model of Po mineralization by clarifying the role and prevalence of “biochemical” and “biological” Po mineralization which we hypothesize are not mutually exclusive and may co-occur along a continuum of Po substrate stoichiometry; 2) further understand the dynamics of phytate, a 6-C compound that can regulate the poorly understood stoichiometry of soil P; 3) explore the effects of C and Po saturation on P sorption and Po mineralization; and 4) resolve discrepancies between hypotheses about P cycling and the methods used to test these hypotheses.

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Use of Cowpea to Manage Soil Phosphorus Accumulation from Poultry Litter Applications in a Cool-season Vegetable Rotation

HortScience ◽

10.21273/hortsci.33.4.591a ◽

1998 ◽

Vol 33 (4) ◽

pp. 591a-591

Author(s):

Clydette Alsup ◽

Brian A. Kahn

Keyword(s):

Cover Crops ◽

Spinacia Oleracea ◽

Soil Phosphorus ◽

Poultry Litter ◽

Vegetable Crops ◽

Cool Season ◽

Soil P ◽

Phosphorus Accumulation ◽

Turnip Greens ◽

Vegetable Rotation

Cowpea [Vigna unguiculata L. (Walp.)] cover crops were grown in a rotation with broccoli (Brassica oleracea L. var. italica Plenck.), spinach (Spinacia oleracea L.), and turnip greens [Brassica rape L. var. (DC.) Metzg. utilis] to evaluate the legume's ability to remove excess P from soils when poultry litter was used as a fertilizer. Fertilizer treatments were litter to meet each crop's recommended preplant N requirements (1X), litter at twice the recommended rate, and urea at the IX rate as the control. Following the vegetable crops, cowpeas were planted on half of each replication, while the other half was fallowed. The cowpeas were harvested for green-shell seeds and then underwent a simulated haying operation. Soil samples were taken at 0-to 15-cm and 15- to 30-cm depths at the onset of the study and after each crop to monitor plant nutrient levels. The cowpeas effectively lowered soil N levels but not soil P levels. However, there was no consistent evidence of an increase in soil P or K levels with litter applications. All three vegetable crops were successfully grown using poultry litter, although the 1X rate appeared inadequate for maximum production of broccoli and turnip greens.

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