William L. Stout

Assessing the efficacy of alternative phosphorus sorbing soil amendments

Concern over the contribution of agricultural phosphorus (P) to fresh water eutrophication has focused attention on practices that decrease P losses from agricultural soils. At present, there are few management options for soils with P levels in excess of crop P requirements other than restricting P applications. This study assesses various readily available materials as possible P Sorbing Soil Amendments (PSSAs) by comparing their near- and long-term effects on soil P solubility and potential availability to runoff with their impact on plant available P. Specifically, anthracite refuse ash, bituminous refuse ash, by-product gypsum (CaSO4), siderite (FeCO3), steel processing sludge, water treatment residual, and wollastonite (CaSiO3) were incubated in three acidic and one neutral loam soils for 21 and 120 days to compare starting and ending water extractable soil P (WEP) and Mehlich-3 P concentrations. Across all soils, bituminous refuse ash, by-product gypsum, and water treatment residual decreased WEP consistently at the lowest rates of application without lowering Mehlich-3 P to less than crop requirements. In addition, no significant difference in WEP and Mehlich-3 P was observed for byproduct gypsum between the 21-day and 120-day incubation periods, indicating that sorption reactions induced by this material are both rapid and stable with time. Anthracite refuse ash, siderite, steel processing sludge, and wollastonite were ineffective at decreasing WEP in soil at practical application rates. Results support the use of by-product gypsum and water treatment residual on acidic and neutral soils representing areas of high P loss potential.

Runoff transport of faecal coliforms and phosphorus released from manure in grass buffer conditions

Aims:  To test the hypothesis that faecal coliform (FC) and phosphorus (P) are transported similarly in surface runoff through the vegetative filter strip after being released from land‐applied manure.

Effect of amending high phosphorus soils with flue-gas desulfurization gypsum on plant uptake and soil fractions of phosphorus

Flue gas desulfurization (FGD) gypsum, a coal combustion by-product, can be used to decrease water-extractable soil P, thereby lowering the potential for P export to surface waters. This decrease results from a conversion of loosely bound inorganic P (IP) which is readily desorbable to water, to less soluble Al- and Fe-bound IP and, to a lesser extent, calcium-bound IP pools. Although this conversion has little effect on predictors of plant-available soil P (e.g., Mehlich-3 P), little is known about the plant uptake of P over several growth cycles after high P soils are amended with FGD. In a greenhouse experiment, we measured P uptake by ryegrass (Lolium perenne) using a modified Stanford–Dement procedure (three growth cycles), and the extent to which IP was being removed from each soil IP fraction (Hedley fractionation), for three soils treated with FGD gypsum (equivalent to 22.4 Mg ha−1). Treatment with FGD decreased water extractable soil P 38 to 57%, but had little effect on Mehlich-3 soil P. During the first growth cycle, the shift from resin IP to less available Al, Fe, and Ca IP remained stable. Repeated growth cycles of ryegrass removed resin IP and thus, had a continued effect on lowering water-extractable P. After three growth cycles and harvests, ryegrass dry-matter production was not affected by FGD treatment (P > 0.05), although cumulative P uptake (20%) and P concentration of ryegrass tops (25%) were greater in FGD treated than untreated soils. Our results confirm that treatment of high P soils with FGD gypsum decreases water-extractable P by conversion to soil IP fractions that are stable with time, does not decrease plant production, and suggests that the potential for P export in surface runoff may be reduced for several years.

Quantitative effects of soil depth and soil and fertilizer nitrogen on nitrogen uptake by tall fescue and switchgrass

Abstract In semi‐arid regions, soil depth influences soil N uptake, but not ferilizer N uptake. How soil depth interacts with soil and fertilzer N to influence N uptake in humid regions is not known. The objective was to determine the relative importance of soil depth and soil and fertilizer N uptake, by forage grasses. Tall fescue (Festuca arundinacea Schreb.) and switchgrass (Panicum virgatum L.) were grown on soils of varying depths. Nitrogen rates are 0, 90, and 180 kgN/ha of 15N depleted (NH4)SO4 applied in a split application on fescue and in one aplication to switchgrass. Total N and fertilizer N uptake, were regressed against fertilizer N, variables related to soil depth (waterholding capacity (WC), water use (WU), water loss (WL), and total soil N (SN). Soil variables explained 28% of the accoutable variation in total N uptake by first cut fescue but only 10% by second cut fescue. Soil variables explained 11% of the accountable variation in fertilizer N uptake by first cut fescue and none by the ...

Agricultural uses of alkaline fluidized bed combustion ash: case studies

Successful programmes were developed by Ahlstrom Development Ash Corporation and Air Products and Chemicals for using fluidized bed combustion ash as a substitute for agricultural lime on dairy farms in northern New York state and on fruit and nut crops in the San Joaquin Valley of California. The companies developed these programmes by utilizing the methodology developed through USDA-ARS research and working closely with agricultural consultants and regulatory agencies to ensure that the ash applications were both agronomically and environmentally sound.

Effect of Mg and Zn fertilization on soil test levels, ear leaf composition, and yields of corn in northern West Virginia

Abstract A corn fertility study was conducted at two locations in northern West Virginia to determine the response of corn (Zea mays L.) to applied Mg and Zn on two soils testing low in Mg by the ammonium acetate and Baker tests and low in Zn by the Baker test. The study consisted of three rates of Mg (0, 112, and 224 kg/ha) and three rates of Zn (0, 3.36, and 6.72 kg/ha) applied in a factorial design. The soil at the Morgantown location was medium textured with a CEC of 22.4, and the soil at the Reedsville location was coarse textured with a CEC of 15.8. Yield responses to applied Mg were obtained only on the coarse textured soil at the Reedsville location where exchangeable Mg was less than 5% of the CEC and equilibrium Mg was less than 9.0 10 ‐4M. No yield response to Zn was obtained at either location.

Effect of early season nitrogen on nitrogen fixation and fertilizer-use efficiency in grass-clover pastures

Grass-legume pastures rely on biologically fixed nitrogen (N) and thus are often N deficient in the spring. To overcome this period of N deficiency, researchers in the United Kingdom (UK), New Zealand (NZ), and recently the United States (US), have developed programs of early season N applications to clover/grass pastures. However, the effect of such early season N application on clover N fixation and N fertilizer N use efficiency of clover/grass swards is not known in the climate of the northeast US. A three-year study was conducted in Pennsylvania on a white clover (Trifolium repens)/orchardgrass (Dactyls glomerata) sward, fertilized with three rates of 15N (22.4, 44.8, and 89.6 kg N ha−1) and cut at three target sward harvest heights (TSHH) (15, 22.5, and 30 cm). The objective of the study was to determine the effects of N fertilization and TSHH on the fraction of clover N derived from fixation (FNDF), the total clover N derived from fixation (TNDF), and fertilizer N use efficiency (FNUE) of the combined sward. Over the three years of the study, full season FNDF in the clover was about 0.90 and the TNDF was about 135 kg N ha−1. The TSHH decreased TNDF during April and May, but this effect disappeared by the end of September. Nitrogen fertilizer use efficiency at the two lowest fertilization rates was greater than 0.50, but decreased to 0.36 at the highest N fertilization rate. The data indicates that, at a 44.6-kg N ha−1 rate and a 15-cm TSHH, the TNDF and the FNUE will be maximized.

Effect of foliar and soil applied zinc on soil test levels, herbage composition, and yields of alfalfa

Abstract Forages in the Northeast generally do not contain enough Zn to meet the National Research Council (NRC) recommended allowance for dairy cattle (40 mg/kg Zn). A study was undertaken to determine if foliar or soil application of Zn could increase Zn levels in alfalfa herbage to the NRC recommended allowance. Alfalfa was treated with Zn by foliar applications of 0.34 and 0.68 kg/ha and soil application of 4.07 kg/ha. An untreated check was also included in the study. Average herbage Zn levels were 33.1 and 50.1 mg/kg for the low and high foliar applications, respectively. These levels were significantly higher than that of the check, 18.9 kg/ha. Average herbage Zn levels for the soil applied Zn treatment was 23.4 mg/kg. This level was also significantly higher than that of the check. Although foliar Zn application significantly raised herbage Zn levels above those of the check, the results were erratic. The 40 mg/kg level was reached only one‐third of the time with the 0.34 kg/ha foliar application ...

VAMA STABILIZATION OF BROKEN FRAGIPAN MATERIAL

Broken Albrights fragipan material was treated with aqueous solutions of from 0.1 to 1.0 percent concentrations of vinyl acetate maleic acid copolymer (VAMA) for 1 min or 12 hr, air-dried, and subjected to a series of wetting and drying cycles (to simulate field conditions) in the laboratory. Approximately one-half of the treated samples were also subjected to overburden weight equal to 2 ft of soil material. Data from the weighted and unweighted studies indicate that fragipan material can be successfully stabilized under simulated field conditions. The amount and duration of stability depends on 1) the concentration of the aggregating agent, and 2) the duration of the contact of the aggregating agent with the fragipan material. In general, increased concentration of VAMA treatment results in a regular decrease in the amount of slumping. The greater the time of contact, other factors constant, the greater the stabilization. This undoubtedly is the result of deeper penetration of the VAMA into the fragipan material with resultant greater stabilization. Overburden weight is also a significant factor. Static weight tends to pack the material into a tighter mass, thus sealing off more water-conducting pores and channelways. At the termination of the study (15 cycles), some of the treated materials were still adequately stabilized, but a projection of the data indicates that even these treatments would fail if subjected to additional cycles. Thus, if extended stability is to be obtained in the field, natural aggregating processes will have to assume the stabilizing function or additional treatments will be necessary. These data indicate further testing in the field is necessary to determine the feasibility of this method for stabilizing broken fragipan material.

Effect of Manure Management on Carbon Evolution and Water Extractable Phosphorus

Soils with excessive phosphorus (P) levels due to manure application are an environmental concern because water extractable P (WEP) in runoff from these soils can contribute to increased amounts P in surface water, which can contribute to eutrophication of freshwater. Phosphorus based manure management is an option to reduce WEP and thereby reduce agricultural P runoff. In P based manure management, manure is applied to meet the P needs of a crop or not to exceed a given soil test level. Because P base manure management does not supply enough nitrogen (N) to meet the needs of the crop, addition fertilizer N needs to be applied. Fertilizer N applied to soils may increase the rate of mineralization of organic matter and lowers soil pH and therefore may affect the solubility of soil inorganic and organic P pools. The extent to which this may affect WEP or plant P availability is not known. Thus, laboratory and greenhouse studies were conducted to determine the effects of P based manure management on WEP and on short‐term P plant availability. Phosphorus based manure management had no significant effect on the shift of organic P to WEP, but the increased acidity due to urea hydrolysis and subsequent nitrification of ammonia had a significant effect on the solubilization of P form the Ca‐bound IP pool, thereby increasing WEP. This could be a significant consideration where Ca‐bound IP dominates IP, P based manure management is implemented and increased WEP is subject to export to surface waters via runoff.