Soil Test Levels Research Articles

Inoculant and fertilizer effects on lentil in the US northern Great Plains

AbstractLentil (Lens culinaris Medikus) is an important crop, averaging over 250,000 ha in Montana and North Dakota during 2016–2021. However, relatively little is known about rhizobial inoculant and fertility response in lentil in the US northern Great Plains. The objective was to evaluate the effect of rhizobial inoculant formulations (seed coat and in‐furrow) and nutrient additions (potassium [K], sulfur [S], and micronutrients) on lentil yield and seed protein concentration. This study was conducted at seven university research centers in Montana and North Dakota from 2019 to 2021, resulting in 20 location‐years of data. In six of 20 experiments, inoculant application increased seed yield by an average of 36% (323 kg ha−1, p ≤ 0.05) but had no consistent effect on seed protein concentration. Lentil or pea crop history among locations did not explain inoculant response. Inoculant formulations (seed coat vs. in‐furrow) and K fertilizer had inconsistent and small effects on seed yield and protein concentration. However, S fertilizer (5.6 kg S ha−1) increased seed yield in four of 20 experiments (p ≤ 0.02) by an average of 14.5% (255 kg ha−1) in those experiments and decreased seed yield for one experiment (p = 0.05) by 5.8% (153 kg ha−1). Pre‐plant SO4‐S soil test levels did not predict lentil response to S fertilizer. Micronutrient application was assessed in 12 location‐years but had no effect on lentil yield or protein concentration. This research suggests a need to better understand what factors control lentil yield and protein response to rhizobial inoculant and S fertilization.

Effect of TNAU-Water Soluble Fertilizers (TNAU-WSF) on Nutrient Uptake and Nutrient Use Efficiencies of Small Onion (Allium cepa var. aggregatum)

To achieve sustainability in agricultural crop production, water-soluble fertilizers were produced around the world. With this view, Tamil Nadu Agricultural University, Coimbatore, has produced TNAU-Water Soluble Fertilizers (TNAU-WSF). The field experiment was carried out in the farmer’s field at Devarayapuram, Coimbatore, to assess the effect of newly synthesized TNAU-Water Soluble Fertilizers (TNAU-WSF) on nutrient uptake and nutrient use efficiencies of small onions. The experiment was conducted in Randomized block design (RBD), which includes eight treatments of different nutrient levels of soil test based application from 125%, 100% and 75% NPK as TNAU-WSF with sulphur and TNAU Multi Micronutrient (TNAU-LMM). The results were obtained as the soil test based application of 125% NPK as TNAU-WSF with sulphur and TNAU-LMM recorded higher nutrient uptake (N, P, K, and micronutrients) and nutrient use efficiencies (agronomic efficiency and apparent nutrient use efficiency) compared to other nutrient levels (100% and 75%).

Soil phosphorus balance in Minnesota soils and its effects on soil test phosphorus and soil phosphorus fractions

AbstractPhosphorus (P) fertilizer recommendations based on the build and maintain (B&M) or the sufficiency philosophies were compared at six sites across Minnesota. Various levels of soil test P (STP) levels were established over four growing seasons. Applied P and P removed in harvested grain were monitored and used to develop a soil net P balance (Net P). Linear regression of net P with changes in STP was highly significant. Initial STP levels could be maintained at four of the six sites with a negative Net P. At those same sites, a zero Net P would tend to slowly increase STP over time. A sequential soil P fractionation analysis was conducted on soils from the six sites at the initiation and at the end of the 4‐year period. Nine total soil P fractions were extracted that represented both inorganic P (Pi) and organic P (Po) in the labile and non or less labile soil P pools. A positive linear relationship between Net P and changes in Pi fractions was significant. As Net P increased, so did the changes in Pi in the Resin, BiCarb, and NaOH fractions. These three fractions accounted for 66% to >100% of the changes in Net P with Resin and NaOH accounting for the majority of Net P. Changes in Net P that were accounted for in the less labile P pools, Sonic and HCl fractions, variable, and difficult to determine. There was little effect of Net P on Po fractions.

Impact of in-furrow fertilizers on winter wheat grain yield and mineral concentration

AbstractPlacement of fertilizer in the seed furrow to increase nutrient availability is a common practice in row-crop production. While in-furrow application of fertilizer is widely utilized in the production of winter wheat (Triticum aestivum L.), there is a lack of work evaluating new formulations and nutrient combinations that are available. The objective of this study was to quantify the effects of in-furrow fertilizer products and combinations of products on winter wheat grain yield, nitrogen and mineral concentrations. Trials were conducted across five site-years in central Oklahoma using 11 fertilizer formulations placed in-furrow at the time of planting. In locations that soil test phosphorus (STP) levels or potassium were above sufficiency, the use of in-furrow fertilizers did not improve yield over the control. Inconsistency of response was noted at locations where STP levels were below the critical threshold. While one location showed no response to the addition of P regardless of source, two other locations had significant yield responses from three or more P-containing fertilizers. The addition of both sulphur and zinc resulted in increased yield over the base product at one low STP location. Nutrient concentrations were also influenced in nutrient-limited soils; however, no trends in response were present. Based upon the results of this study, the application of in-furrow fertilizer has the potential to increase winter wheat grain yield and nutrient concentration, when soil nutrients are limiting. As expected the addition of fertilizer when soil test levels are at or above a sufficiency did not increase grain yield.

Effect of topdressing of compost, compost tea, and various fertilizers on soil and lawn characteristics

AbstractMany cities in the United States collect and compost yard waste but need more effective and efficient ways to utilize the finished product. Home lawns represent a sizeable area that could benefit from land application of yard waste compost, but little research has been conducted regarding topdressing lawns with compost. The objectives of this study were to compare the impact of topdressing yard waste compost relative to organic and inorganic fertilizers in a mature, predominantly Kentucky bluegrass (Poa pratensis L.) lawn in Wisconsin. Three different composts (two from yard waste and one from food waste), two organic fertilizers, and a compost–compost tea combination were compared against a traditional synthetic fertilization program and a nontreated control. Treatments receiving compost (1.3 cm depth per year, in two equally sized applications) maintained acceptable turf quality over the 3.5‐yr study period and resulted in significant improvements in several important physical properties of the soil. Fertilizers were also able to maintain acceptable turfgrass quality but had no impact on the physical properties of soil over the study period relative to the control. Organic and synthetic fertilizers reduced weed populations compared with the control, though the compost treatments did not. Compost and one of the organic fertilizers significantly increased the levels of soil test P but did not reach levels of environmental concern.

Soil Test Levels to Guide Nutrient Stewardship: Phosphorus and Potassium Focus for the North‐Central Region

While monitoring soil test levels for essential crop nutrients is most important on the field or subfield scale, assessing trends across broader geographies can indicate the direction of where past and current management practices are leading us. This article discusses the soil fertility status of the U.S., specifically the North‐Central region, informed by the 2020 North American Soil Test Summary, and what can be interpreted to guide nutrient management decisions at different geographical scales. Earn 1 CEU in Nutrient Management by reading the article and taking the quiz at https://bit.ly/3aR26gE. View all CEUs online at https://web.sciencesocieties.org/Learning‐Center/Courses.

Evaluation of nutrient status of kale and spinach as affected by sewage sludge and mineral fertilizers

The main objective of this study is to investigate the cumulative effect of mineral fertilizers and sewage sludge on nutrient status of kale (Brassica oleracea L. cv. ‘GM Dari’) and spinach (Spinacia oleracea L. cv. ‘Shalimar Green’). The experiment was carried out in a completely randomized block design with nine treatments including: no fertilizer or sewage sludge as a control (T 1), 25% Sewage Sludge + 0% Recommended fertilizer dose (RFD) (T 2), 50% Sewage Sludge + 0% RFD (T 3), 75% Sewage Sludge + 0% RFD (T 4), 100% Sewage Sludge + 0% RFD (T 5), 25% Sewage Sludge + 75% RFD (T 6), 50% Sewage Sludge + 50% RFD (T 7), 75% Sewage Sludge + 25% RFD (T 8), and 0% Sewage Sludge + 100% RFD (T 9). The recommended fertilizer doses are made to apply fertilizers to meet the nutrient requirements of the crop and to build up the nutrient level in the soil to a critical soil test level over a planned time frame usually recommended by agronomists. The results of the study showed that the concentration of all macro nutrients (N, P, K, Ca, and Mg), micro nutrients (Mn, Cu, Zn, and Fe) and heavy metals (Cd, Cr, Pb, and Ni) in both kale and spinach were significantly highest in the plots treated with 75% sludge + 25% NPK, whereas, the values of these elements in control treatments were recorded to be the lowest. However, the total nitrogen content in spinach and lead concentration in kale remained significantly higher under the treatment of 50% sludge + 50% NPK. The study lead to an important conclusion that the treatment of soil with 75% sewage sludge + 25% NPK can improve the nutrient accumulation in these plants thereby enhancing yield production.

Do soil test levels and fertilization with phosphorus and potassium impact field crop tissue concentrations?

AbstractSoil testing and plant tissue nutrient concentrations form the basis for fertilizer recommendations in Ohio. The response of crop phosphorus (P) and potassium (K) nutrient concentrations to soil test levels and fertilizer applications influences fertilizer recommendations but have not been rigorously evaluated in this region. The objective of our study was to determine the effects of (a) soil test P and K levels and (b) P and K fertilization on mid‐season leaf and grain P and K concentrations of corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and wheat (Triticum aestivum L.). From 2014–2018, we conducted 186 on‐farm trials (99 P, 87 K trials) over a diversity of soil types, crop genetics, and management histories in 39 counties throughout Ohio. Soil test P and K levels, mid‐season leaf P and K concentrations, and grain P and K concentrations were measured on randomized and replicated plots. Both leaf and grain nutrient concentrations generally increased with the soil test levels, but the relationships were weak in all three crops. Fertilization of P and K marginally but consistently increased leaf tissue concentrations in all crops but had a lesser effect on grain P and K concentrations. Our data suggest that current sufficiency ranges for corn, soybean, and wheat are too high and need revision. Collectively, our results show that crop P and K tissue concentrations are positively, but weakly related to soil test levels and fertilization, and this information has important implications for future development of nutrient management frameworks in Ohio.

Corn yield response to sub-surface banded starter fertilizer in the U.S.: A meta-analysis

Abstract Sub-surface fertilizer application at planting (i.e., starter fertilization) is a common practice in U.S. corn (Zea Mays L.) production to improve early-season nutrient uptake, nutrient use efficiency, and plant growth, especially under cool and moist spring soil conditions. However, yield increases from starter applications can vary across production systems and environments. Here, we use a meta-analysis approach to quantify and generalize corn yield responses to sub-surface starter fertilizer applications in the U.S. and to understand the management and environmental factors that drive variability in corn yield response across previously published research. This meta-analysis summarizes peer-reviewed research from the U.S. published between 1990 and 2019. The dataset encompasses 474 observations from 23 studies conducted in various locations and includes information regarding management practices used and soil and weather conditions. We calculated effect size as the natural log of the response ratio, with the response ratio determined as corn yield with a starter fertilizer application containing nitrogen (N) and phosphorus (P) or N, P and potassium (K) relative to corn yield without a starter fertilizer application. Additionally, we investigated the impact of potential moderator variables on corn response to sub-surface starter fertilization (e.g. agronomic practices, soil properties, and weather conditions). On average, fertilizer sub-surface applied in the furrow or banded 5 cm to the side and 5 cm below the seed at planting increased corn yield by 5.2 %. Corn response to starter fertilization was consistent across many agronomic and environmental conditions including different tillage systems, previous crops, soil textures, and planting season weather conditions. Yield benefits decreased with increasing soil test P and K levels. Nevertheless, yield increases from starter fertilization occurred with soil test levels up to 500 % and 300 % of the P and K critical levels, respectively. In addition, corn yield benefits from starter fertilization decreased as corn planting density increased and as corn yield level decreased. Overall, this meta-analysis provides support for the use of sub-surface starter fertilizer applications to improve corn yield.

Effect of fly ash as a source of silicon and potassium on the disease incidence of Brown leaf spot in rice under different abiotic stress condition

Experiments were carried out in two field conditions (induced drought and flood stress) to analyse the effect of fly ash which is a source of silicon on incidence of brown leaf spot disease (Helminthosporium oryzae) and grain yield of rice. The treatments include fly ash, Silicate Solubilizing Bacteria (SSB), Farm yard manure (FYM), and graded levels of soil test based potassium. The results revealed that the combination of Fly ash, SSB, FYM, with graded level of soil test based potassium significantly reduced the incidence of Brown leaf spot disease as compared to untreated plots. The silicon content was analysed in the leaf blade and it was negatively correlated with the brown leaf spot disease. As the age of the plant increased, silicon content proportionately increased in the plants at different growth stages. Further, the incidence of brown leaf spot was negatively correlated with yield. Application of fly ash as a source of silica and potassium with SSB, FYM with STBK reduced the incidence of Brown leaf spot and increased the yield in rice.

To study the effect of fertilizer doses and soil test levels on crop response of Brinjal

To study the effect of fertilizer doses and soil test levels on crop response of Brinjal

In‐Season Application of Nitrogen and Sulfur in Winter Wheat

Core Ideas Decreased atmospheric deposition has led to increased S consumption in winter wheat. Sulfur did not increase yield or grain N concentration at any site. Use of recommended soil testing guides are encouraged. Decreased atmospheric S deposition in the past 20 yr has led to increased S fertilizer consumption in winter wheat (Triticum aestivum L.). Producers often apply S without any soil test information. Experiments were conducted at Lahoma, Lake Carl Blackwell, and Perkins, OK (2011–2013) to assess the effect of N and S applied preplant and foliar on grain yield and grain N for winter wheat. In 2011–2012, urea ammonium nitrate (UAN) was applied preplant at rates of 40 and 80 kg N ha−1 additionally; UAN and urea‐triazone (NSURE) were foliar‐applied at rates of 10 and 20 kg N ha−1. Sulfur was foliar‐applied as gypsum (CaSO4⋅2H2O) at 6 kg S ha−1. In 2013, trials were altered to apply 40 kg N ha−1 as UAN preplant, and 20 kg N ha−1 foliar‐applied. Gypsum rates were adjusted at 0, 3, and 6 kg S ha−1 preplant, and S (MAX‐IN‐S) at 3 and 6 kg S ha−1 was foliar‐applied. Sulfur did not increase grain yield or grain N concentration at any site. The interaction between foliar S and N and preplant S and N was not significant. Sulfur fertilizer application is less likely to benefit this region unless low levels of soil test S are identified before planting. Use of recommended soil‐testing guides are encouraged. Although S applications are encouraged commercially, no response was observed in these trials, and all were on sites where soil organic carbon was low (<8.5 g kg−1), where the possibility of seeing S deficiency was greater.

Foliar and Granular Fertilizer Effects on Creeping Bentgrass and Soil Nutrient Levels

Core Ideas Foliar fertilizer treatments did not deplete soil nutrient levels after three years of applications. Combining foliar and granular fertilizers resulted in the best turfgrass quality. Biweekly application of foliar fertilizers resulted in higher turf quality than monthly granular fertilizer applications. Research was conducted to determine the effects of foliar and granular fertilizers on creeping bentgrass [Agrostis stolonifera var. L. palustris (Huds.) Farw. ‘Penn A4’] quality and soil nutrient levels of two putting green rootzones. The hypothesis was foliar fertilizers would decrease soil nutrient levels and result in lower turfgrass quality over 3 yr compared to granular fertilizers. The fertilizer treatments were granular urea, methylene urea, and natural organic, foliar fertilizer at two rates, foliar‐granular combination, and an untreated control. The two rootzones were a United States Golf Association (USGA) guideline rootzone and a sandy clay loam (58% sand, 20.5% silt, and 21.5%) native soil. The urea, methylene urea, natural organic, and foliar‐granular treatments were applied at 0.5 lb N/1000 ft2/month from May through October. The foliar treatment was applied at two rates, 0.25 and 0.5 lb N/1000 ft2/month from May through October. Soil samples were collected from 2009 to 2011 and turfgrass quality was rated every 2 weeks. Turfgrass growing on native soil had consistently higher quality than turfgrass on the USGA rootzone and native soil had higher soil NO3–N, P, and K levels than the USGA rootzone. Neither the foliar, granular, or combination treatments decreased soil NO3–N, P, or K levels compared to initial soil test levels over 3 year of research. Every two weeks, applications of both the combination and foliar 2X treatments produced higher turfgrass quality than monthly methylene urea, urea, and organic treatments. Although the 0.25 lb N/1000 ft2/month foliar treatment had a lower N rate than all fertilizer treatments, it had acceptable quality throughout the research.

Low soil phosphorus and potassium limit soybean grain yield in Ohio

A soil survey was conducted in Ohio with the following objectives: (i) to assess the status of soil fertility; (ii) to examine soybean grain yield in areas with fertility levels in the build‐up range, where soil test levels were less than the critical level (CL); the maintenance range, where soil test levels were between the CL and maintenance limit (ML); and the drawdown range, where soil test levels were greater than the ML; and (iii) to determine if the soil test and yield data collected support the state‐established fertility recommendations. Earn 0.5 CEUs in Soil & Water Management by reading this article and taking the quiz at www.certifiedcropadviser.org/education/classroom/classes/496.

Low Soil Phosphorus and Potassium Limit Soybean Grain Yield in Ohio

Core Ideas Twenty‐one percent of the soil samples were within the build‐up range for P. Twenty‐three percent of the soil samples were within the build‐up range for K. Soybean yield decreased when soil test P and K were within the build‐up range. A soil survey was conducted in Ohio with the following objectives: (i) to assess the status of soil fertility; (ii) to examine soybean grain yield in areas with fertility levels in the build‐up range, where soil test levels were less than the critical level (CL); the maintenance range, where soil test levels were between the CL and maintenance limit (ML); and the drawdown range, where soil test levels were greater than the ML; and (iii) to determine if the soil test and yield data collected support the state‐established fertility recommendations. Soil sampling was conducted from 2013 through 2015 resulting in 593 total samples. Soil P, K, Ca, Mg; pH; organic matter (OM); and cation exchange capacity (CEC) were measured. Soybean grain yield was also collected from the sampling areas. Twenty‐one and 23% of the soil samples collected were within the build‐up range for P and K, respectively. On average, grain yield was 7 bu/acre lower in sampling areas associated with soil P levels in the build‐up range, whereas an average grain yield reduction of 4 bu/acre was associated with K levels in the build‐up range. In sampling areas, there was no difference in grain yield associated with soil P and K levels within the maintenance range and drawdown range. Our data suggest that soil test levels within the build‐up range were associated with lower soybean grain yields.

Crop production impacts on soil phosphorus removal and soil test levels

ABSTRACTAn 8-year field study documented the impact of tillage, crop rotations, and crop residue management on agronomic and soil parameters at Brookings, South Dakota. The greatest annual proportion of above-ground biomass phosphorus (P) removed was from the grain (78–87% of total) although crop residue removed some P as well. Greater above-ground total biomass P (grain P + crop residue P) was removed from corn than from soybean and spring wheat crops mainly due to the greater corn grain biomass harvested. Cumulative above-ground biomass P removal was greatest for the corn-soybean rotation (214 kg P ha−1), while it was lowest for the soybean-wheat rotation (157 kg P ha−1). Tillage treatments within crop rotation or residue management treatments did not influence annual or cumulative P removal rates. Olsen extractable soil orthophosphate-P levels declined consistently through time from a mean of 40 µg g−1 (2004) to 26 µg g−1 (2011). Biomass P removal was calculated to be 15.7 ha−1 yr−1 to decrease Olsen extractable soil orthophosphate-P levels by 1 µg g−1 yr−1 over 8 years of the study.

Managing Potassium and Phosphorus Soil Test Levels in a Rice–Soybean Rotation

A long‐term rice–soybean (Oryza sativa L.–[Glycine max (L.) Merr.]) rotation was conducted at Glennonville, MO, to determine how quickly farmers need to increase soil test levels in low‐phosphorus (P) and ‐potassium (K) fertility fields. Plots received P and K fertilizer to increase soil Bray‐1 P and ammonium acetate–extractable K in 1‐, 4‐, or 8‐year buildup programs. In most years, soybean and rice yields from plots receiving P and K fertilizer treatments were significantly greater than yields from untreated controls. Two soil test P and K target levels were tested. The soil test target for rice using University of Missouri recommendations was 22% lower for P and 36% lower for K than the soybean target. No justification was found for recommending lower soil test P and K target levels for rice than soybean. Averaged across buildup programs, rice produced significantly greater yields using the soybean P and K soil targets than the rice P and K targets. Averaged over years, soybean and rice yields were not affected by the length of time in P and K buildup programs. Farmers can prolong buildup of soil test P and K over 4 to 8 years without yield losses.

Nitrogen and Sulfur Fertilization Effects on Camelina Sativa in West Central Kansas

Camelina sativa is early maturing and possesses characteristics that make it a good fit as a rotation crop in dryland wheat cropping systems. Nitrogen (N) and sulfur (S) play very important roles in oilseed production, including camelina. This study was conducted over 3 years to determine N and S rates necessary for optimum camelina production in west central Kansas. The experiment was set up as randomized complete blocks with four replications in a split-plot arrangement. Treatments were two sulfur rates (0 and 18 lb/a) as the main plots, and four N rates (0, 20, 40, and 80 lb/a) as the sub-plot. Sulfur application did not affect stand count, biomass yield, harvest index, seed yield, oil and protein content. However, stand count, biomass yield, seed yield, and protein content were affected by N application (P < 0.05). Average oil and protein content were 28.1% and 33.9% respectively. The optimum N rate for yield was 20 lb N/a, which produced around 680 lb/a seed yield. Based on soil test levels of 25 lb N/a, N requirement for camelina production is 45 lb N/a.

Building soil potassium and phosphorus in a low‐testing fescue hay field

A fescue hay field in the Ozark Highlands received phosphorus (P) and potassium (K) fertilizer to build up soil test levels above target levels. Fertilizer rates were applied to build the soil test P and K levels in one, four, or eight years. Averaged across eight years, hay yields were not significantly different between build‐up timings. However, compared with the untreated control, hay yield and quality were significantly increased by applying P and K. Earn 1 CEU in Nutrient Management by reading this article and completing the quiz at www.certifiedcropadviser.org/certifications/self‐study/666.

Potato Management Challenges Created by Phosphorus Chemistry and Plant Roots

A primary objective of phosphorus (P) management is to maintain optimal levels of P in the soil solution at the root surface. Potato plants typically have low root density, resulting in higher solution P concentration needs and critical soil test levels than most other common crop plants. The chemistry of P in fertilized soils makes maintaining these high P concentrations a challenge. Phosphorus has a very high affinity for the soil solid phase with iron (Fe) and aluminum (Al) dominating reactions in moderately acid soils and calcium (Ca) in alkaline soils. Guidelines for P stewardship for potato production are: (1) adopt practices that develop soil conditions that favor root growth and development; (2) make source, rate, time and placement decisions for nutrient applications that maintain optimal soil solution P concentrations during critical growth stages; and (3) use soil and water conservation practices to minimize P losses from the root zone and the field.