Isotopic tracing of phosphorus uptake in corn from 33P labelled legume residues and 32P labelled fertilisers applied to a sandy loam soil

Abstract

In low input (e.g. organic) farming systems where soil phosphorus (P) fertilisers such as superphosphate are not used, maintaining sufficient available soil P for plant growth can be a major challenge. The use of P accumulating cover crops may increase P availability for subsequent crops. We hypothesised that P release from organic residues of legumes (faba bean (Vicia faba) and field peas (Pisum sativum)) could supply adequate P to meet the needs of a subsequent crop in a low P soil. A pot experiment was conducted to determine the contribution of P by legume green manure to subsequent corn using 33 P labelled legume residues and 32 P labelled inorganic fertiliser (KH 2 PO 4 ). The treatments included two rates of P application, (a) 10 kg P ha −1 as legume root and shoot residues or as inorganic fertiliser with and without a C source, and (b) 38 kg P ha −1 as a combination of legume shoot and root residues or a combination of root and inorganic fertiliser and inorganic fertiliser alone. An absolute control (zero P) was also used. Shoot dry matter, P uptake and P source (residues or fertilisers) of total P in corn were measured at harvest. Faba bean and field pea residues alone or in combination with fertilisers contributed up to 10% and 5% of the total P uptake by corn respectively, compared with up to 54% by inorganic fertilisers. Incorporation of field pea and faba bean residues with P concentrations higher than those observed under field conditions, may not always lead to adequate net P release to supply the early growth phase of subsequent crops.

Effect of soil phosphorus availability and residue quality on phosphorus transfer from crop residues to the following wheat

“…Thus there was no consistent pattern for the relative P transfer from the residues to the wheat shoots with minimal effects from the soil P status or from the P concentration in the residues. These results are consistent with those from earlier studies (Maltais-Landry and Frossard 2015; Mat Hassan et al 2012b;McLaughlin and Alston 1986;Nachimuthu et al 2009;Noack et al 2014) which used finely ground residues incorporated in the soil. They found the residue contribution to P uptake, in the short term, was up to 20% of the total P introduced in residues.…”

Agronomic and environmental aspects of phosphate fertilizers varying in source and solubility: an update review

“…Unlike nitrogen (N), which can be top-dressed as fertilizer 2-3 times during the growing season, generally P fertilization entails a one-time basal application to the soil before or soon after plant emergence. Because organic P must be converted to inorganic P through a relatively slow mineralization process before it becomes available to plants, organic fertilizers may not meet plants' early P requirements, often resulting in lower crop yield (Nachimuthu et al 2009). Furthermore, unlike conventional chemical N fertilizers which are all water soluble, P fertilizers vary widely in solubility that can influence the initial and residual P effects.…”

Phosphorus utilization by corn as affected by green manure, nitrogen and phosphorus fertilizers

“…Phosphorus deficiency is a major constraint to crop production in most tropical and subtropical acid soils, and P fertilizers are required to sustain optimum crop yields (Pypers et al, 2005;Nachimuthu et al, 2009). In Brazil, low soil pH, combined with incorrect management of N and P fertilizations, is the main responsible for low corn yields.…”