Long-Term Impact of Tillage Practices and Phosphorus Fertilization on Soil Phosphorus Forms as Determined by ³¹ P Nuclear Magnetic Resonance Spectroscopy

Abstract

Conservation tillage practices have become increasingly common in recent years to reduce soil erosion, improve water conservation, and increase soil organic matter. Research suggests that conservation tillage can stratify soil test phosphorus (P), but little is known about the effects on soil organic P. This study was conducted to assess the long-term effects of tillage practices (no-till [NT] and mouldboard plowing) and P fertilization (0 and 35 kg P ha) on the distribution of P species in the soil profile. Soil samples from a long-term corn-soybean rotation experiment in Québec, Canada, were collected from three depths (0-5, 5-10, and 10-20 cm). These samples were analyzed for total P (TP), total C (TC), total N (TN), pH, and Mehlich-3 P (PM3); P forms were characterized with solution phosphorus-31 nuclear magnetic resonance spectroscopy (P-NMR). Results showed a stratification of TP, TC, TN, pH, PM3, and Mehlich-3-extractable aluminum and magnesium under NT management. The PM3 and orthophosphate concentrations were greater at the soil surface (0-5 cm) of the NT-P (soil treatment with 35 kg P ha) treatment. Organic P forms (orthophosphate monoesters, especially -IP, and nucleotides) had accumulated in the deep layer of NT treatment possibly due to preferential movement. We found evidence that the NT system and P fertilization changed the distribution of P forms along the soil profile, potentially increasing soluble inorganic P loss in surface runoff and organic P in drainage and decreasing bioavailability of inorganic and organic P in deeper soil layers.

Nongrowing season soil surface nitrate and phosphate dynamics in a corn–soybean rotation in eastern Canada: in situ evaluation using anionic exchange membranes

“…Messiga et al (2012) measured greater P M3 under fertilized NT in comparison with MP soils. On the same experimental site, Abdi et al (2014) reported the stratification of P M3 and orthophosphate concentrations under NT management. The transformation of residual P derived from fertilizer into less labile forms might be limited under NT, because broadcast P fertilizer interacts with plant residues, blocking sorption sites, and therefore, adsorption or fixation on the solid phase (Messiga et al 2012).…”

“…The transformation of residual P derived from fertilizer into less labile forms might be limited under NT, because broadcast P fertilizer interacts with plant residues, blocking sorption sites, and therefore, adsorption or fixation on the solid phase (Messiga et al 2012). In addition, the limited transfer of residual P from the enriched upper layer to depleted lower layers due to the low mobility of P also contributed to the differences in soil test P between the P 0 treatment and the P-fertilized plots (Messiga et al 2012;Abdi et al 2014). …”

“…Agricultural practices, including tillage, fertilization, and crop rotation, could affect the transformation and movement of soil N and P. Studies have shown that notill (NT) management has caused the stratification of soil organic carbon (Zibilske et al 2002), nitrate (Grant and Lafond 1994;Lupwayi et al 2006), and extractable P (Cade-Menun et al 2010;Messiga et al 2012;Abdi et al 2014). Previous studies conducted in Canada reported that fertilized NT had a greater soil mineral N and extractable P in the top 5 cm layer and to some extent down to 10 cm, and a depletion of N and P in sublayers; however, soil mineral N and extractable P uniformly distributed down to 20 cm under moldboard plow (MP) (Lupwayi et al 2006;Cade-Menun et al 2010;Messiga et al 2012).…”

Decimetric‐Scale Two‐Dimensional Distribution of Soil Phosphorus after 20 Years of Tillage Management and Maintenance Phosphorus Fertilization

“…A literature review on P distribution in the soil profile of fertilized NT cropland shows greater soil test P concentrations in the top 5-cm layer and, to some extent, down to the 10-cm depth, as well as a marked depletion of P in subsequent sublayers (Abdi et al, 2014;Cade-Menun et al, 2010). Messiga et al (2012) observed low soil test P concentration in the 10-to 20-cm layer of fertilized NT plots in comparison with MP plots, indicating that under NT, P was depleted in this layer.…”

Conservation Agriculture and Soil Quality– An Overview

“…Numerous studies also showed P stratification in soil under different tillage systems where ZT system associated with higher concentration of P due to preferential movement of P in the soil (Abdi et al, 2014). Moreover, the shallower incorporation of crop residues and fertilizer P as well as small P losses due to water erosion under CA leads to higher P contents in the surface soil.…”