Fertilizer Recommendations For Corn Research Articles

Can nitrogen recommendations for corn production be improved through spatially explicit crediting of cover crops and soil organic matter?

Managing N supply to corn (Zea mays L.) properly is a major challenge, with consequences of mismanagement ranging from N-deficient, low yielding crops to pollution of surface and groundwater. For much of the 20th and 21st centuries, N fertilizer recommendations for corn have been calculated by multiplying the yield goal by a constant equal to the amount of N needed per mass of corn grain. While this approach is often sufficient to support the growing crop without tremendous environmental consequences, it does not explicitly consider N mineralized from soil organic matter (OM) or the dynamics of N mineralization or immobilization caused by previous cover crop residues. While typical N management practices used by farmers have led to relatively low N use efficiency, precision agriculture technologies developed in the late 20th century held the promise of improving N management by considering spatial variability in crop fields and adjusting fertilizer rates accordingly. To date, however, few farms use precision agriculture technologies for managing N. In this experiment, we tested a new N recommendation system based on a biogeochemical model, the soil and cover crop available nitrogen (SCAN) model, which explicitly considers OM and cover crop residue pools of N. We coupled this new N recommendation system with variable rate precision agriculture technology to generate spatially explicit N recommendations in corn fields. We hypothesized that this approach to N management would: (i) reduce the amount of N recommended for a corn crop compared to a yield goal approach while, (ii) maintaining corn yield at a level similar to that in a traditional yield goal approach. We found that the SCAN model reduced N rates at four of the six sites compared to the yield goal approach but recommended greater N application at two of the six sites. At one of the sites where the SCAN model recommended higher N rates, we also observed increased grain yields. However, when the SCAN model recommended lower N rates than the yield goal approach, we typically observed reduced yields. Additional research is needed to identify the proper agronomic nitrogen efficiency to use in the SCAN model.

Recalibrating the Pennsylvania pre‐sidedress soil nitrate test recommendations for modern corn production

AbstractThe pre‐sidedress soil nitrate test (PSNT) was developed over 30 years ago to determine sidedress nitrogen (N) fertilizer recommendations for corn (Zea mays L.). Since the original PSNT calibrations were developed, changes in production practices such as no‐till and cover cropping and increases in corn yields and N use efficiency could affect the accuracy of PSNT recommendations. To update the PSNT recommendations in Pennsylvania and demonstrate the test's efficacy, we compiled a dataset of 32 calibration sites and 13 demonstration sites where the PSNT was conducted, and the economically optimum N rate (EONR) for corn was determined from an N fertilizer yield response curve. We recalibrated the PSNT recommendation algorithm and compared its accuracy to the original calibration. The new calibration resulted in a single long‐term manure history factor that interacted with the PSNT result to adjust the sidedress N recommendation (−5.7 kg N ha−1 [mg NO3‐N kg−1]−1). The new calibration also included a term for a mixed species cover crop, which increased the sidedress N recommendation 56.2 kg N ha−1. Finally, the coefficient that scales the N fertilizer recommendation based on yield goal decreased by 29% from the original calibration to 12.9 kg N Mg−1 grain. The new algorithm for predicting EONR reduced the error of the sidedress N recommendation by one‐half compared to the original calibration. The new PSNT calibration will allow users to accurately determine sidedress N recommendations in sites with a long‐term manure history and underscores the importance of updating soil fertility recommendation algorithms with modern data.

Can soil biology tests improve phosphorus and potassium corn fertilizer recommendations?

AbstractIntegrating soil health (SH) biological properties with soil fertility (SF) evaluations offers a unique opportunity to potentially refine fertilizer recommendations. The objectives of this research included: (a) evaluating current University of Missouri P and K fertilizer recommendations for corn (Zea mays L.) and (b) assess whether SH biological indicators are effective predictors of yield response to P and K fertilization. In Missouri, 446 monitoring sites (148 m2) were implemented on 101 production corn fields over the 2018–2020 growing seasons. For each monitoring site, SH and SF samples were collected prior to planting, followed by application of nonreplicated single‐rate fertilizer treatments: (a) unfertilized control; (b) 112 kg ha–1 K2O; and (c) 112 kg ha–1 P2O5. At monitoring sites below recommended critical soil test values, P (n = 152) and K (n = 86) fertilization increased yield at 42 and 36% of the sites respectively, with average yield increasing 10 and 11% for P and K, respectively. At the lowest fertility ratings, P and K fertilization increased yield at 52 and 56% of sites, respectively, highlighting inherent uncertainty within current recommendations. Integrating SH with SF indicators failed to improve random forest algorithms prediction of yield increases from P or K fertilization. Further, variable importance ranking confirmed that current physiochemical SF tests remain the most effective factors identifying when a fertilizer response will likely occur. Although SH metrics may offer insight into other agronomic or environmental benefits, established SF evaluations remain the most effective available tool for guiding P and K fertilizer decisions in Missouri corn production.

Relationships between N, P, and K in corn biomass for assessing the carryover effects of winter pasture to corn

Pasture fertilization may influence the subsequent corn crop in integrated crop-livestock systems, but few tools exist to assess the likelihood and magnitude of this carryover effect. Our goals were to determine whether a previous pasture with N fertilization could supply adequate N nutrition to a succeeding corn crop and affect its P and K nutrition using the concept of N dilution curve and relationships between N, P, and K in corn shoot biomass. The experiment consisted in a winter grazed pasture followed by a corn crop in summer. Treatments were N fertilization of a black oat (Avena strigosa) winter pasture (0 and 200 kg N ha−1) as main plots and four sidedress N fertilization rates (0, 100, 200, and 300 kg N ha−1) applied to corn as sub-plots in a randomized complete block design with split-plot restriction. The N nutrition index, that is, the ratio of observed shoot N concentrations to critical N concentration determined by a critical N dilution curve, adequately identified situations of deficient N nutrition in corn following a pasture with or without N fertilization. This carryover effect from a winter pasture should therefore be accounted for in N fertilizer recommendations for corn in tropical soils. Corn P nutrition, based on critical P concentrations derived as a function of N concentration, was nearly optimal when no N was applied to the pasture, but it was less than optimal when N was applied. Although no critical K curves have been published, our results confirm that the relationship between shoot K and N concentrations varies with the level of N nutrition as does the relationship between shoot P and N concentrations. Our results confirm that the concept of critical N and P concentrations serves as a useful reference to assess the status of N and P nutrition during corn growth in tropical soils with the potential to improve nutrient management of corn following a pasture in an integrated crop-livestock system.

Feasibility Study of Using Absolute SPAD Values for Standardized Evaluation of Corn Nitrogen Status

Nitrogen fertilizer recommendations for corn (Zea mays L.) should ensure high yields using adequate N doses. Soil–plant analysis development (SPAD) meter technology using absolute SPAD values, might be more reliable than relative SPAD values in helping corn producers making timely decisions about N applications. This study aimed to develop a relationship between absolute SPAD values and leaf N concentration, and to determine optimal leaf N concentrations at early corn growth stages (V6, V8, V10, and V12). Three experiments were conducted during two summer seasons (2014 and 2015) using six N treatments applied at early corn growth stages. In parallel, two experiments were carried out in a high residual N environment to establish the optimum corn leaf N concentration. Results showed a significant linear relationship between corn leaf N concentrations and absolute SPAD values (R2 = 0.80, p < 0.05). The mean optimum corn leaf N concentration decreased over corn growth stages. It is of great importance to make the absolute SPAD method accessible for farmers, but more research is required to perform standardized reading of absolute SPAD values data.

Assessing corn response to nitrogen after poultry litter application

Nitrogen (N) fertilizer recommendations for corn (Zea mays L.) should provide adequate rates of N to ensure high yields but should not recommend more than is economical and environmentally sound. The objective of this study was to evaluate the rate of inorganic N fertilization (INF) using the University of Arkansas Cooperative Extension Service (standard recommendation), and the spectrum technology recommendations (app-method) at situations where poultry litter (PL) was applied. Experiments were performed in 2013 and 2014, on a silt loam soil with high residual nitrate-N to evaluate the standard and the app-method. In both years, results showed no significant differences in yield between treatments receiving 0 kg N ha−1 and treatments receiving the standard and the app recommendations at V6, V8, V10 and V12. Although results showed that there was no need for N after PL amendment, the app recommendations averaged 177 kg N ha−1 over the V6 to V12 growth stages versus 246 kg N ha−1 for the standard recommendation. The data collected in this study determined no need for inorganic N when PL is applied. Future research should further evaluate the PL management under a wide range of environmental conditions.

Erratum: Predicting Field‐Apparent Nitrogen Mineralization from Anaerobically Incubated Nitrogen

Fil: Reussi Calvo, Nahuel Ignacio. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata; Argentina. Laboratorio de Suelo S.a.; Argentina

Predicting Field‐Apparent Nitrogen Mineralization from Anaerobically Incubated Nitrogen

Core IdeasStudy aimed to predict field N mineralization (Nmin) from anaerobically incubated N (Nan).Nandid not predict Nminin areas with contrasting edaphic‐climatic properties.Nminwas predicted by a model including Nan, temperature and rainfall.The nitrogen (N) released after a 7‐d anaerobic incubation (Nan) is a good estimator of the size of the soil N mineralizable pool. However, there is a lack of information on how soil properties and climate affect the apparent field N mineralization (Nmin) of this pool. The objective of our study was to develop and validate a simple model to estimate Nminfrom Nanin corn (Zea maysL.) and wheat (Triticum aestivumL.) fields. To this end, we performed 100 field experiments where we measured Nmin, Nan, rainfall, temperature (TC), soil texture, pH, soil organic matter (SOM), and pre‐sowing mineral N concentration (Ninitial). We performed a stepwise analysis to develop a model to predict Nminusing data from 70 sites, while the rest of the data was saved for model validation. The Nanranged from 16 to 94 mg kg–1while Nminranged from 22 to 232 kg ha–1. There was a strong association between Nanand Nminwithin regions with similar climate and edaphic properties. However, we could not fit a single significant model to estimate Nminbased solely on Nanto be used in all regions. By considering other variables besides Nan, we developed a model that allowed predicting Nminindependently from the site [Nmin= –252 + 12.3(TC) + 1.37(Nan) + 0.27(rainfall)] (R2= 0.89, model validationR2= 0.83). This model could be useful to adjust N fertilizer recommendations for corn and wheat, reducing the economic and environmental impact of fertilization.

Over‐Fertilization Does Not Build Soil Test Phosphorus and Potassium in Ohio

Core IdeasCorn and soybean yield seldom responded to P and K fertilization over 9 yr.Soil test P and soil test K significantly decreased from values initially in the recommended maintenance range.Corn Leaf P and Leaf K was often below the sufficiency concentration.Appropriate P and K fertilizer recommendations for corn (Zea maysL.) and soybean [(Glycine max(L.) Merr.] in Ohio are essential, as water quality and nutrient management issues in the region have intensified over the last several years. The objectives of this study were to: (i) evaluate corn and soybean grain yield response to P and K fertilization, (ii) examine soil test phosphorus (STP) and potassium (STK) and corn Leaf P and Leaf K trends, and (iii) compare the ability of soil and leaf tissue testing to reflect corn and soybean response to fertilization. We evaluated three P and K fertilizer rates, no fertilizer (0×), an estimated nutrient removal rate (1×), and twice the estimated nutrient removal rate (2×), in corn–soybean rotations at three sites over 9 yr. Grain yield was generally non‐responsive to P and K fertilization, with only 9 of 42 site‐years yielding significantly positive responses. Soil test P and K started in the maintenance range, but significantly declined with the 1× rate at two of three sites for P and at all sites for K. Furthermore, the 2× rate of P and K failed to build STP and STK at any site, with significant declines at one site. The results revealed an inability to maintain initial STP and STK levels with the 1× rate and call into question the suitability of current fertilizer P and K recommendations aimed at maintaining STP and STK. These recommendations require updating to better reflect fertilizer needs of modern corn and soybean.

Phosphorus Availability to Corn and Soybean Evaluated by Three Soil-Test Methods for Southern Brazilian Soils

To select and evaluate the effectiveness of multi-element soil-test methods for extracting plant-available phosphorus (P), correlation studies are needed. Under natural conditions, corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] were sequentially cultivated in 9-L microplots for 45 days to determine the amount of P that would be absorbed from 49 diverse soils of Rio Grande do Sul State in southern Brazil. Before planting, soil P was extracted with Mehlich 1 solution, Mehlich 3 solution, and ion- exchange resin. The abilities of Mehlich 1, Mehlich 3, and resin to extract plant-available P were then compared. The coefficients of determination obtained between plant P and the amounts extracted by Mehlich 1, Mehlich 3, and resin were 0.59, 0.45, and 0.59, respectively, for corn and 0.57, 0.57, and 0.52 for soybean. Soil P extracted by the three methods was highly correlated; however, the amount of P extracted by the methods was affected by the clay content of the soils. As the clay content increased, the amount of P extracted by the resin also increased, whereas P extracted by the Mehlich 3 solution decreased. Because soil clay content influences extractable P values, soil clay classes are needed to properly calibrate soil P status and fertilizer recommendations for corn and soybean grown on these soils.

Illinois Soil Nitrogen Test Predicts Southeastern U.S. Corn Economic Optimum Nitrogen Rates

An accurate and quick soil N test is needed for N fertilizer recommendations for corn (Zea mays L.) for the humid southeastern USA. The Illinois soil N test (ISNT) has been used to distinguish fertilizer-responsive from unresponsive sites in Illinois. We determined relationships between economic optimum N rates (EONR) and ISNT levels in representative southeastern soils in 35 N-response trials in the Piedmont (n = 4) and Middle (n = 8) and Lower (n = 23) Coastal Plains of North Carolina from 2001 to 2004. The ISNT was strongly correlated with EONR for well or poorly drained sites (r2 = 0.87 [n = 20] and 0.78 [n = 10], respectively); data were insufficient for establishing correlations for very poorly drained or severely drought-stressed sites. Expressing ISNT on a mass per unit volume basis vs. EONR improved the correlations slightly (r2 = 0.88 and 0.79 for well and poorly drained sites, respectively), but these improvements would not justify the necessary soil bulk density determinations. Regressions of ISNT vs. minimum, average, and maximum EONR based on different N-fertilizer cost /corn price ratios (11.4:1, 7.6:1, and 5:1, respectively) showed strong correlations with EONR for well-drained sites (r2 = 0.77, 0.87, and 0.87, respectively) and poorly drained sites (r2 = 0.84, 0.78, 0.70, respectively). The ISNT–EONR correlations were different among the cost/price ratios for well-drained sites, but not different for poorly drained sites. Because ISNT predicted EONR robustly to different cost/price ratios, ISNT has the potential to modify or replace current N recommendation methods for corn.

Border row effect on corn grain response to sidedressed nitrogen fertilizer1

Nitrogen (N) fertilizer recommendations for corn (Zea mays L.) are normally developed from field experiments that determine yield response to applied N. The objective of this study was to examine the severity of border row competition with the harvest rows for sidedressed N in field experiments measuring grain yield. This study was conducted in 1993 and 1994 on a Sharpsburg silty clay loam (fine, montmorillonitic, mixed, mesic argiudoll). Ammonium nitrate was broadcast to the center two rows of a four row plot, all four rows of a four row plot and all six rows of a six row plot. Results showed that grain yield from four and six row plots were similar and indicated that while grain yields were much less in 1993 than 1994 (7.36 versus 12.06 Mg ha‐1, respectively), corn yield response to N was similar regardless of the number of rows fertilized. Thus, there is little reason for plots larger than four rows. The results also lend credibility to sidedressing only harvest rows for soil test calibration studies where grain yield response is the primary response variable.

Analysis of Aerial Photography for Nitrogen Stress within Corn Fields

AbstractSpatial variability of soil parameters within fields complicates N fertilizer recommendations for corn (Zea mays L.) production. Thus, the ability to identify differences in crop N status within corn fields could lead to efficiencies in N fertilizer application and decreased ground water pollution. In this study, we digitized aerial color photographic transparencies using an eight‐bit scheme to generate digital counts for the red, green, and blue primary colors in the photographs at the R5 growth stage and related them to grain yield. Digital count responses were relative to the N treatment in which grain yield plateaued. Experiments were conducted in 1992 and 1993 for four irrigated corn hybrids with five N rates on a 6‐ha field near Shelton, NE. Red and green digital counts relative to those for the high N treatment provided better prediction of yield response than relative blue counts in both years. In 1993, black‐and‐white photographs taken with a filter centered around 536 nm also predicted yield response to N well (r2 = 0.93). These findings permit the use of low cost aerial photographs to characterize variability in crop N status throughout entire fields.

Banding urea and lignosulfonate in corn (Zea mays L.) production and 15N recovery

The use of urea in corn (Zea mays L.) production is common. Under current N fertilizer recommendations for corn, urea may have adverse effects on corn growth when applied in a band. The effects of ammonium lignosulfonate (LS) on corn growth and on N uptake from the banded application of urea and diammonium phosphate (DAP) mixtures were investigated on two soils from eastern Quebec. Field experiments were initiated in the first week of May 1991 on an Ormstown silty clay and a Ste. Rosalie clay soils (fine, mixed, nonacid, mesic Typic Humaquepts). Treatments were two rates of urea (30 and 90 kg urea-N ha−1) in combination with DAP (14 kg N ha−1), with or without banded fertilizer solutions of LS (8 kg N ha−1) applied at planting 5 cm to the side and 3 cm below the seed. A no treatment control was included. The low rate of urea and DAP (no LS added) resulted in a 19 and 24% increase in grain yield at the Ste. Rosalie and Ormstown, respectively, when compared with the unfertilized plots. When compared with the unfertilized treatment, the high rate of urea and DAP (no LS added) caused 10% increase in grain yield. However, addition of LS to the high rate of urea and DAP increase grain yield by band 20%. In general, LS significantly increased corn N uptake from urea on both soils. Separate 15N field experiments were initiated in June 1991. Mean recovery of 15N in total dry matter (grain and stover) was 51.9% in Ormstown and 47.9% in Ste. Rosalie soil. Denitrification estimates, calculated as 15N not accounted for, were not affected by LS and the rate of banded urea-N. Immobilization of 15N ranged from 17.8% to 30.9% of the applied labelled urea. The rate of urea-N banded had no significant effect on immobilization, but LS resulted in significantly less 15N immobilized. These observations suggest that LS can reduce the biological immobilization of urea-N and increase the efficiency of urea fertilizer by reducing the negative effects of banding high levels of urea, while attaining benefits of band placement. Key words: Lignosulfonate, corn, urea, 15N

Long-Term Phosphorus and Potassium Application to Corn on Coastal Plain Soils

The effect of long-term fertilizer applications on soil test levels, yield, and crop removal depends on soil texture and mineralogy. The objectives of this study were to measure the fluctuations in soil P and K in soils of varying texture and to evaluate the usefulness of the Mehlich-1 soil extractant in predicting yield response. A field experiment was conducted for 11 yr on two soils : a Tifton loamy sand (fine-loamy, siliceous, thermic Plinthic Kandiudults) and a Greenville sandy clay loam (clayey, kaolinitic, thermic Rhodic Kandiudults). Phosphorus treatments were 0, 92, 183, and 275 lb P 2 O 5 lb/acre in the first year followed by annual applications of 0, 37, 73, and 0 lb/acre, respectively. Potassium treatments were 0, 48, 96, and 144 lb K 2 O/acre in the first year followed by annual applications of 0, 48, 96, and 0 lb/acre, respectively. Soil samples (0-6 in.) were collected each year at tasseling of the corn (Zea mays L.) crop, P and K concentrations were determined in soil and grain samples, and yield was measured. Initial application rates influenced initial soil test levels, and annual application rates affected the rate of change of soil test levels with time. All significant yield increases on the Greenville soil were due to P application. Phosphorus moves rapidly from solution into less available forms in the Greenville soil due to the soil's high P fixing capacity. Yield increases on the Tifton soil resulted from K applications, presumably due to greater leaching losses on the sandier textured soil. The Mehlich-1 extractant provides a questionable measure of soil P availability for corn. Particularly in areas where P runoff potential is high, P fertilizer should not be applied to irrigated corn in the Southeast unless the Mehlich-1 extractable soil P concentration ≤ 12 lb/acre. Data from this long-term study show that accounting for soil K below the plow layer may improve the use of mehlich-1 extractant as a measure of K availability for corn.

Correlations between nitrogen and N uptake and yield of corn grown in three tillage systems

Abstract Nitrogen fertilizer recommendations for corn in South Dakota are based on a soil test for inorganic N, but data is limited concerning how different tillage systems affect N uptake and yield of continuous corn. Relationships between total N uptake and yield of corn, N03‐N contents at different sampling depths taken either in the spring or fall were studied in 1988 and 1989 on an Estelline soil located in eastern South Dakota. The test consisted of three tillage systems (chisel, moldboard, and ridge) and 5 N rates (0, 65, 130, 195, and 260 kg N/ha). Results indicated that NO3‐N samples taken in the fall to a depth of 60 cm were better correlated with N uptake and yield than spring sampled soils. The correlations in 1988 between fall NO3‐N and uptake were linear for the chisel and moldboard system but quadratic for the ridge system. In 1989 the response was quadratic for the chisel and moldboard system but linear for the ridge system. The relationship between fall NO3‐N and corn grain yield was line...