Assessment of Soil Phosphorus and Potassium following Real Time Kinematic‐Guided Broadcast and Deep‐Band Placement in Strip‐Till and No‐Till

Abstract

Fertilizer placement may cause non‐uniform nutrient distribution in the soil, making it difficult to determine whole‐field fertility by traditional sampling strategies. Our objectives were to determine P and K distribution after repeated applications in no‐till and strip‐till soils and to develop improved sampling procedures to estimate soil P and K levels on a corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation with crops planted at 76‐cm row spacing. Three trials near Pesotum, IL, received blends of 0–0, 22–42, 33–62, 44–83, 55–104, 66–125, and 77–145 kg P–K ha−1 in fall 2007 and 2009 before corn planting. Applications were broadcast‐applied in no‐till (NTBC) and strip‐till (STBC) and deep‐banded in strip‐till (STDB) 15 cm below the surface in the crop row (IR) using real‐time kinematic (RTK) satellite navigation. Every year soil P and K was measured at 10‐cm increments to a 30‐cm depth at 0, 19, 38, and 57 cm from the IR. Subsurface banding reduced P and K levels in the surface and increased them at the point of application, or deeper with the highest rate, while broadcast applications increased surface levels. Soil‐surface K levels were greater at IR likely because of K leaching from senescing standing crops. Soil‐test results indicated no need to adjust fertilizer rate based on tillage or fertilizer placement. A sampling ratio of 1:3 IR to between the crop rows (BR) seemed adequate to estimate soil fertility across a wide range of P‐ and K‐fertilizer rates and soil test levels where the location of the fertilizer band or planting row is maintained constant.

Deep Banding Increases Phosphorus Removal by Soybean Grown under No‐Tillage Production Systems

“…5). Similar results were reported in previous studies (Fernández and Schaefer, 2012;Mallarino and Borges, 2006). Comparing residual P from NT-BR vs. ST-DB, the results from this study suggest that deep band fertilization has lower potential for runoff and environmental P loses (Hale et al, 2015;Nkebiwe et al, 2016).…”

“…5). These results showed the potential challenges for soil sampling and soil test determination at whole-field scale by traditional sampling strategies (Fernández and Schaefer, 2012). In the long term, plant P uptake and P partitioning between plant parts can also promote a non-uniform re-distribution of P in the soil profile (Clarkson et al, 1978, Xue et al, 2014.…”

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

“…Those authors observed no change in soil test P concentrations under NT for broadcast application across all sampling positions with respect to the crop row for the top 30 cm of the soil. In contrast, increases in soil P levels were observed at the crop row relative to interrow positions at maintenance or recommended fertilizer P rates for subsurface-band fertilization (at 15 cm below the soil) (Farmaha et al, 2012;Fernández and Schaefer, 2012) or injection (at 10 cm below the soil) (Duiker and Beegle, 2006). Continuous band applications of P in the same soil volume result in a substantial localized increase in soil P test levels and depletion in the rest of the rooting zone.…”

“…Evidence of such two-dimensional (2-D) spatial variability, both vertical and horizontal, in NT was highlighted in a 2-yr study under a corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation with crops planted at 76-cm row spacing (Fernández and Schaefer, 2012). Those authors observed no change in soil test P concentrations under NT for broadcast application across all sampling positions with respect to the crop row for the top 30 cm of the soil.…”

Corn Grain Yield Trends from 2012 to 2016: A 26-Year Long-Term Experiment

“…The benefits also represent an efficient use of inputs and lower environmental impact. Under CT practices, soil nutrient dynamics are more susceptible to losses in the envi-ronment by soil erosion, losses to the atmosphere, and leaching (Cook and Trlica, 2016;Fernández and Schaefer, 2012;Young et al, 2009). …”