Sugarcane green harvest management influencing soil phosphorus fractions

Authors: LUIZ-CORREIA, BENEDITO - Federal Rural University Of Pernambuco; Kovar, John; THOMPSON, MICHAEL - Iowa State University; PAVINATO, PAULO - Universidad De Sao Paulo; FERRACCIU ALLEONI, LUIS - Universidad De Sao Paulo

Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2023
Publication Date: 4/3/2023
Citation: Luiz Correia, B., Kovar, J.L., Thompson, M.L., Pavinato, P.S., Ferracciú Alleoni, L.R. 2023. Sugarcane green harvest management influencing soil phosphorus fractions. Soil & Tillage Research. 231. Article 105713. https://doi.org/10.1016/j.still.2023.105713.
DOI: https://doi.org/10.1016/j.still.2023.105713

Interpretive Summary: Throughout the world, there is increasing interest in efficient use of phosphorus (P) fertilizer, as reserves of this essential element are finite. Sugarcane production is a large agricultural industry in Brazil, so it is vital to that country’s economy. Due to environmental and legal issues, there has been an increase in mechanically harvested sugarcane. Residues are not burned under this system, so water, nutrient, and organic matter dynamics are affected. Traditionally, growers apply from 100 to 180 kg P2O5 per ha, and this accounts for a significant part of production costs. As a consequence, there is interest in soil P cycling. Differences in the decomposition of sugarcane residues may influence P cycling. With a laboratory study, we evaluated concentrations of various soil P compounds in green-harvest and burned-harvest systems. In general, concentrations of inorganic P compounds did not differ between harvest systems. There also was no relation between inorganic P and soil depth in the two harvest systems. However, soil organic P compounds had accumulated in the 0.2-0.3 m layer under the green-harvest system, which is where P fertilizer is commomnly applied at planting. Our results suggest that green-harvest management of sugarcane promoted cycling of plant-residue P and increased mineralization of soil organic P. This may increase P availability and decrease the fertilizer required for the subsequent crop. The results of this work improves our understanding of P cycling in diverse soils, and will contribute useful information to sugarcane producers in both Brazil and the U.S., where burning is being eliminated as a production practice.

Technical Abstract: Few studies have examined phosphorus (P) forms in tropical soils managed with green harvest (GH) of sugarcane (Saccharum officinarum L.) and minimum-tillage practices. We evaluated concentrations of total P, total organic P (total Po), inorganic P (Pi) bound to aluminum (Pi-Al) and iron (Pi-Fe), Pi occluded in Fe and Al oxides (Pi-occluded), Pi bound to calcium (Pi-Ca), as well as residual P (Pi+Po). Soil samples from an Oxisol were collected at depths of 0-0.05 m, 0.05-0.1 m, 0.1-0.2 m, 0.2-0.3 m, and 0.3-0.4 m from the planting row, 0.25 m perpendicular to the row, and in the inter-row. Of the fractions, the total Po pool showed the greatest variation between the GH and traditional systems in which sugarcane is burned before harvest. Total Po concentration was lower in the 0-0.05 m soil layer of the GH system than in the burned-harvest (BH) system and had accumulated in the 0.2-0.3 m layer, which is where P fertilizer was applied at planting. These differences were observed in the planting row and 0.25 m from the planting row, but not in the inter-row. In general, concentrations of Pi forms did not differ between harvest systems. There also was no relation between Pi forms and row position or sampling depth in the two harvest systems. Our results suggest that GH management of sugarcane promoted cycling of plant-residue P and increased mineralization of soil organic P, which may increase P availability and decrease the fertilizer required for the subsequent crop.