Long‐Term P and K Applications: II. Effect on Corn and Soybean Yields and Plant P and K Concentrations

Abstract

Increasing emphasis on environmentally sound nutrient management requires an improved understanding of fertilizer P and K needs for profitable crop production. A 20‐yr study was conducted on two glacial till soils to determine: (i) the effect of various P and K rates on corn (Zea mays L.) and soybean (Glycine max (L.) Merr.] yields and profitability during a 12‐yr application phase and an 8‐yr residual phase, and (ii) whether triennial applications of P and K produce crop yields equal to those from annual applications. Initial Bray P1 and exchangeable K soil tests were 22 and 150 ppm, respectively, for the Webster clay loam (tine‐loamy, mixed, superactive, mesic mic Endoaquolls) and 10 and 228 ppm, respectively, for the Aastad clay loam (fine‐loamy, mixed Pachic Udic Haploboroll). Phosphorus and K were applied annually for 12 yr at rates of 0, 50, and 100 lb P2O5/acre and 0, 50, and 100 lb K2O/acre while rates of 150 lb P2O5/acre and 150 lb K2O/acre were applied every third year. Yields were improved by the 50‐ lb P2O5 rate in 6 of 12 yr when the soil test P (STP) was <22 ppm for the Webster soil and in 8 of 12 yr when the STP was ≤10 ppm for the Aastad soil. Yields were not improved further by the 100‐lb P2O5 rate on either soil. Yields from triennial P application were similar to those from annual P application in 23 of 24 siteyr. Annual application of fertilizer K increased yield only in 3 of 24 site‐yr. During the 8‐yr residual period, yields were increased above the control in all 15 site‐yr by carryover from the 541b P2O5 rate. Corn yields were optimized at leaf K concentrations ranging from 1.14 to 2.29%, indicating the importance of knowing nutrient uptake characteristics of hybrids when assessing the K status of corn. Economic return was generally highest with the 150‐lb P2O5 rate applied every third year. Results from this study indicate that most profitable long‐term returns can be obtained with broadcast applications of 150 lb P2O5/acre on a triennial basis and by monitoring STP and soil test K (STK) to take advantage of residual availability. Research Question Economically profitable and environmentally sound crop production requires a better understanding of long‐term fertilizer P and K applications for improved nutrient management. The objectives of this study were to determine the effects of P and K fertilizer rates on corn and soybean yields and profitability during a 12‐yr application phase and a subsequent 8‐yr period to measure the residual effect, and to compare triennial applications of P and K with annual applications of the same total quantity of nutrients. Literature Summary Soil testing lab summaries indicate that soil test P (STP) and K (STK) frequently have been built to High and Very High levels by fertilization during the past 30 to 40 yr. Studies reported during the past 10 yr, however, indicate little, if any, yield response by corn or soybean to fertilizer P and K applications when STP or STK are in the Mediuim or higher range. Some studies have recommended that profits could be i...

Shifts in Soybean Yield, Nutrient Uptake, and Nutrient Stoichiometry: A Historical Synthesis‐Analysis

“…Larger yields were associated with improvement in K uptake, reductions in K seed and KHI, and a substantial increment in K stover , leading to a reduction in KIE over time. Increases in K stover were also reported by others (Heckman and Kamprath, 1995; Randall et al, 1997; Clover and Mallarino, 2013).…”

“…In this review, K stover was larger in Eras II and III than in Era I, which can be related to the increase in K fertilization since 1960 (USDA‐ERS, 2016). Several authors have reported increases in K stover with K fertilization and without yield response in corn and soybean (Heckman and Kamprath, 1995; Randall et al, 1997; Clover and Mallarino, 2013). Luxury nutrient uptake occurs when uptake is above the crop requirement for a target yield level.…”

The potassium paradox: Implications for soil fertility, crop production and human health

“…Many leguminous crops are sensitive to Cl − toxicity, including soybean 120,131 and alfalfa 159,160,198 , and Cl − can reduce soil N availability by inhibiting nitrification in soils 195,196,199,200 (see also supplementary references [53][54][55] for the online version of the paper) and by acting as a competitive anion that suppresses plant uptake of NO 3 − 147,201,202 (see also supplementary references [38] and [56][57][58][59] for the online version of the paper). A further difficulty arises from the mobility of Cl − in soils, which intensifies profile leaching of Ca 2 + as a counterion [203][204][205] .…”

Modeling Nitrogen Dynamics under Maize on Ferralsols in Western Africa

“…In these developing countries, the challenge is the optimization of the use of small amounts of fertilizer N affordable by resource-poor farmers (Atchou 1988;Pieri 1989;Saragoni et al 1991), unlike industrialized councomplex. Studies using drain lines and lysimeters to collect drainage water have been conducted to address fertilizer N use efficiency, nitrate leaching, and water quality issues (Magdoff et al 1984;Roth and Fox 1990;Angle et al 1996;Randall et al 1997;Sogbedji et al 2000;Fofana et al 2004), but efficient N management remains a challenge due to the complexity associated with N dynamics in the soil-plant-atmosphere system (Kladivko et al 1991;van Es et al 1991). Addiscott et al (1991) concluded that, as many physical, chemical and biological processes affecting soil N can happen practically at once, any attempt at a simultaneous description of its dynamics requires an explicit, computer-based, model.…”