Tillage and Phosphorus Management Effects on Crop Production in Soils with Phosphorus Stratification

Abstract

Reduced-and no-tillage seedbed preparation methods coupled with broadcast P applications lead to an accumulation of available P in the surface 0-to 5-cm soil layer and a depletion of available P deeper in the profile. A 3-yr study determined the effects of tillage and fertilizer P management on P uptake and grain yield for P-stratified soils. Tillage practices were moldboard plow (once at the start of the study followed by reduced tillage), reduced tillage (disk followed by field cultivation), and no-tillage. Four P management methods were imposed: (i) no P; (ii) 20 kg P ha 21 applied as a surface broadcast; (iii) 20 kg ha 21 applied as a banded starter, 5 cm to the side and 5 cm below the seed; or (iv) 20 kg ha 21 applied in a deep placed band, 13 to 15 cm on 0.7-m centers. The one-time moldboard plowing produced higher early season dry matter yields for corn (Zea mays L.), wheat (Triticum aestivum L.), and soybean [Glycine max (L.) Merr.] compared with the no-tillage system, but tillage effects on final grain yield were inconsistent. Subsurface placement of P generally increased P uptake and grain yield of corn and sorghum [Sorghum bicolor (L.) Moench], but had little effect on grain yield of soybean. Results indicate that subsurface applications of P fertilizers should be considered if soil test P is highly stratified within the surface 0-to 15-cm layer and the 15-cm composite is medium or below for available P.

Phosphorus fertilization, soil stratification, and potential water quality impacts

“…No-till induced P stratification in cotton (Gossypium hirsutum) has resulted in a recommendation to update fertility recommendations for no-till soils (Howard et al 1999). Others have also concluded that in highly P stratified soils, P should be subsurface applied (Robbins and Voss 1991;Schwab et al 2006).…”

“…No-till induced P stratification in cotton (Gossypium hirsutum) has resulted in a recommendation to update fertility recommendations for no-till soils (Howard et al 1999). Others have also concluded that in highly P stratified soils, P should be subsurface applied (Robbins and Voss 1991;Schwab et al 2006).It is therefore important for conservationists and agronomists to understand the potential role of no-till induced P stratification on SP losses. Further, if these fields do pose a potential risk, there is currently no fertility management or conservation practice guidance to alleviate these potential risks.…”

Speciation of Phosphorus in a Fertilized, Reduced‐Till Soil System: In‐Field Treatment Incubation Study

“…Reduced-tillage crop production is gaining more attention from farmers in many regions of the United States and on farms worldwide (Hobbs et al, 2008). Despite various advantages of reduced-tillage systems, granular P applications have been found to lead to an accumulation of available P on the surface (0-5 cm) soil layer and a depletion of available P deeper in the profile (Schwab et al, 2006), which could be intensified further due to deposition of crop residues. Phosphorus stratified at the soil surface may support plant root growth under moist conditions at initial stages of plant growth; however, roots explore deep soil layers for nutrients and moisture as surface soil dries in summer, so plants may suffer from low nutrient availability.…”

“…Phosphorus stratified at the soil surface may support plant root growth under moist conditions at initial stages of plant growth; however, roots explore deep soil layers for nutrients and moisture as surface soil dries in summer, so plants may suffer from low nutrient availability. Bordoli and Mallarino (1998) suggested that deep placement of nutrients (below the first 5-10 cm of the soil) may be superior to other placements such as broadcast when nutrient stratification and topsoil moisture deficits reduce nutrient uptake from shallow soil layers, but inconsistent results have been obtained from research conducted to study the effects of tillage and deeper placement of P fertilizers on grain yields of crops grown in Kansas soil with P stratification (Schwab et al, 2006). We hypothesized that in a reduced-tillage system, P placement-broadcast vs. deepbanding-can have significant influence on P fertilizer reaction products.…”

Phosphorus and nitrogen fertiliser use efficiency of wheat seedlings grown in soils from contrasting tillage systems.

“…On the alkaline soils of north-western Victoria, O' Leary and Connor (1997) found that stubble retention and tillage had a variable effect (increased in 1 year out of four but reduced it in two out of 4 years) on soil mineral N accumulation on a Vertosol (425 mm annual rainfall environment) whereas on a Calcarosol at Walpeup (325 mm annual rainfall) there was no effect. Tillage / crop residue management has been shown to affect nutrient availability (especially N mineralisation) in a range of cropping systems including the United States (Schwab et al 2006), New Zealand (Haynes and Knight 1989), Canada (Grant and Lafond, 1994) and northern Europe (Thomsen and Sorensen 2006). However surprisingly few studies have investigated the effect of tillage directly on fertiliser use efficiency, especially of P and N combined.…”