Alternative N Fertilizer Management Strategies Effects on Subsurface Drain Effluent and N Uptake

Demonstrating positive environmental benefits of alternative N fertilizer management strategies, without adversely affecting crop growth or yield, was a major goal for the Midwest Management Systems Evaluation Areas (MSEA) program. Our project objectives within this program were to quantify the effects of split- and single-N fertilization strategies on NO3-N concentration and loss in subsurface drain effluent and N accumulation and yield of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. The study was conducted on glacial till derived soils in northeast Iowa from 1993 through 1995 using no-till and chisel plow tillage treatments. One-third of the 2,611 effluent samples had NO3-N concentrations greater than 10 mg L–1. Split applying fertilizer N based on pre-sidedress soil nitrate test (PSNT) results significantly increased corn yield for both tillage treatments in the extremely wet 1993 without increasing NO3-N loss in drain effluent. Increased grain yield also resulted in significantly more N removal. When fertilizer N was applied based on the PSNT, no-till and chisel treatments had similar NO3-N losses and concentrations. Average flow-weighted NO3-N concentrations in drain effluent were not increased when larger amounts of fertilizer were applied based on PSNT. However, prior crop and tillage practices and differences in drain flow volume caused significant differences in NO3-N losses and concentrations. These results suggest that spatial differences in flow volume are a major factor determining NO3-N loss in drainage effluent. Significant differences suggest that combining no-tillage practices with split N fertilizer management strategies can have positive environmental benefits without reducing corn yield

The use of heavy minerals in studies of the origin and development of soils

Publication authorized February 22, 1945."The experimental material here presented is taken from the Ph.D. thesis... by J.F. Haseman in the University of Missouri, June, 1944"--P. [3].Digitized 2007 AES.Includes bibliographical references (pages 72-75)

Preferential flowpaths and fertilizer placement influence subsurface P transport across soil textures and seasonal conditions

Agricultural tile drains are a source of phosphorus (P) contributing to eutrophication. Preferential flowpaths can rapidly transport P to tile drains, but their activation in different soil textures and under variable seasonal conditions (antecedent moisture conditions and presence of soil frost) is not well understood. Subsurface placement of fertilizer has been proposed as a management practice to reduce P loss, compared to surface applications. However, how subsurface placement reduces P loss is not well understood. The goal of this thesis is to relate subsurface flowpaths and fertilizer placement to identify source and transport mechanisms controlling P movement to tile drains, across soil textures and seasonal conditions. A lab experiment was done on intact soil monoliths (clay, silt loam) to investigate interactions between fertilizer placement, subsurface flowpaths, and soil frost. Conservative water tracers (Brˉ, Clˉ and D₂O) applied through successive events identified matrix flow as the dominant flowpath in unfrozen silt loam, while preferential flow dominated in unfrozen clay and in both soil types under partially frozen conditions. Subsurface placement of fertilizer reduced dissolved reactive P losses by 60% in silt loam and 64% in clay over the simulated non-growing season compared to surface broadcast applications. A field study used blue dye as a tracer to investigate subsurface flowpaths in clay and silt loam plots under wet and dry conditions. Dye stain patterns were analyzed to determine the relative importance of matrix and macropore flow. Soil samples were collected to determine soil P distribution post-fertilization. Preferential flow occurred under all soil texture and moisture conditions. Dry clay soil showed the deepest staining (92 ± 7.6 cm), followed by wet clay (77 ± 4.7 cm). In silt loam soil, depth of staining did not differ between wet (56 ± 7.2 cm) and dry (50 ± 6.6 cm) conditions. Soil water-extractable P distribution varied with fertilizer application in the top 10 cm of the soil profile, but did not differ at depth. Together, the results of this research suggest subsurface placement is a suitable practice for minimizing subsurface nutrient loss, by reducing contact between the nutrient supply and preferential flowpaths, particularly in clay soils prone to preferential flow. This work provides an improved understanding of subsurface flowpaths carrying P to tile drains, and more broadly, solute transport through preferential flowpaths

Some physical and biochemical effects of fumigants in soils

Thesis (Ph. D.)--Michigan State College of Agriculture and Applied Science. Department of Soil Science, 1951Includes bibliographical references (page 116-120

Concentration and Off-target Movement of Neonicotinoid Residues During Agricultural Practices in Southwestern Ontario

Neonicotinoid insecticides are important globally to control pests in numerous agricultural crops, representing 24% of total agricultural insecticide use. Recently, exposure of non-target organisms to neonicotinoids present in various agricultural matrices is debated as a result of their use as seed treatments in field crops. Field sampling and laboratory studies were conducted from 2013 to 2016 to determine concentration and movement of soil bound residues and particulate matter exhausted from vacuum type planters during the planting of neonicotinoid treated seed. “Wick effect” was reported as an important process that results in accumulation of neonicotinoid residues in the soil surface. Total suspended particulate (TSP) concentrations of neonicotinoid are higher at the edge of fields during planting than tillage of fields. Neonicotinoid residues were detected during wind events, tillage and planting practices. Efforts should be directed towards reducing the amount of material dislodging from treated seeds and reducing the amounts of contaminated dust exhausted by the planter. Avoiding excessive tillage and practicing soil conservation can be useful in minimizing the off-site transport of neonicotinoid residues.Ontario Ministry of Agriculture, Food and Rural AffairsCorn Dust Research ConsortiumOntario Soil and Crop Improvement AssociationAgriculture and Agri-Food CanadaBayer CropScienceSyngentaBAS

Effect of FeHEDTA on Magnetic Properties of Soil

Industrial, agricultural and urban activities may introduce anthropogenic pollutants into the local, regional and/or global environment. As soils can accumulate these pollutants, soil monitoring can be used in environmental assessments. Geophysical methods are used to provide rapid, nondestructive, and diagnostic soil monitoring. Magnetic methods are often used; however, environmental magnetic studies of soils have other purposes, including the study of climate variations and soil forming processes. This study examined the effects of a common iron-based herbicide (iron hydroxylethylenediaminetriacetic acid aka FeHEDTA) on soil magnetic properties. The magnetic properties of FeHEDTA control samples in varying concentrations (5-50% by weight in gypsum powder), untreated specimens from soils of Windsor-Essex County (Ontario Canada) and FeHEDTA-treated specimens from the same soils were examined. Magnetic susceptibility (χlf, χhf), frequency-dependent magnetic susceptibility (χfd), artificial remanence analysis (isothermal and anhysteretic), and hysteresis measurements were used to determine the extent of the FeHEDTA effects. The results indicate that: 1) FeHEDTA additions of >26% by weight to the gypsum powder resulted in a magnetic signature characteristic of superparamagnetic magnetite; 2) the effect of FeHEDTA is most evident in soils with comparatively lower initial magnetic mineral concentrations; and, 3) the effect of FeHEDTA in clay rich soils was an increase in χfd, suggesting that the FeHEDTA was reacting with clay minerals to increase the iron concentration in treated soil samples. The results suggest that the standard application dose of FeHEDTA for weed-killing would have negligible effects on soil; however, over-application or direct application to soil could result in a small measurable effect