Claypan Soil Research Articles

Topsoil Thickness Influences Nitrogen Management of Switchgrass

Switchgrass (Panicum virgatum L.) is an attractive bioenergy crop option for eroded portions of claypan landscapes where grain crop production is marginally profitable. Topsoil thickness above the claypan, or depth to claypan (DTC), can vary widely within fields, and little information exists on its impacts on N management of switchgrass. Therefore, a study was conducted at the University of Missouri South Farm near Columbia, Missouri, to determine whether topsoil thickness influenced fertilizer N requirements of switchgrass. Switchgrass was planted in 2009 on main plots with a range of DTC classified as exposed ( 30 cm) and was harvested annually at postdormancy during 2011 to 2015. Three split-plot treatments were 0, 67, or 101 kg N ha−1 applied annually in May, and a fourth was three intercropped native legumes as the N source. Across years, the legume treatment apparently supplied no N because it produced the same or less switchgrass yield than the nonfertilized treatment. Topsoil proved valuable as switchgrass yield, nutrient removal, and profit usually increased as DTC increased. Fertilization with 101 kg N ha−1 on exposed, shallow, or moderate DTC and 67 kg N ha−1 on deep DTC was required to obtain the highest biomass yield, but it also increased nutrient removal. Strikingly, profit across years was negative for the legume treatment and highest with no fertilizer on all DTC classes. Therefore, improvements are needed before intercropped legumes are profitable, and N fertilization may be needed only periodically to maximize switchgrass profit on claypan soils.

Site-Specific Erodibility in Claypan Soils: Dependence on Subsoil Characteristics

Abstract. Soil erosion is a primary factor limiting the productive capacity of many crop production fields and contributing to sediment and nutrient impairments of water bodies. Loss of topsoil is especially critical for areas of limited topsoil depth, such as the claypan area of the central United States. More than a century of conventional agricultural practices have eroded the topsoil and, in places, exposed the unproductive clay layer. This clay layer is impervious, limiting water infiltration and root penetration, and severely restricting agricultural productivity. Previous studies have documented changes in topsoil thickness using apparent electrical conductivity (ECa). However, that methodology is limited by its shallow depth of measurement within the soil profile, and as such cannot adequately explore factors within the soil profile that potentially contribute to topsoil erosion. In this study, we identified areas of limited topsoil depth using crop yields and ECa. Two areas within the production field varying in crop production and ECa were selected for detailed measurements using Electrical Resistivity Tomography. This methodology allowed delineation of soil stratigraphy to a depth of 5.3 m. The erodibility of undisturbed soil samples from the two areas were measured in an Erosion Function Apparatus to obtain the critical shear stress, or the applied stress at which soil begins to erode. Based on resistivity measurement, the highly productive region of the field had a thick (1.0-2.0 m) soil layer of saturated clayey sand soil over a uniform sandy material, with minimal clay layer. This soil had a critical shear stress of 12 Pa. The extent of historical erosion was evident in the poorly-producing area, as only a thin band of topsoil material remained over a thicker clay layer. The unproductive area with exposed clay layer had a critical shear stress of 128 Pa, indicating it was more resistant to erosion than the highly productive region. The clay layer was found to extend to 1.3-1.5 m in depth in the soil profile in the poorly producing area. Below this layer was a layer with similar resistivity to the high-producing region. The data reveal the extent of historical erosion within the crop production field and highlight significant variability in measured soil properties within a field of identical production practices. While spatial variations in topsoil have long been considered in developing management practices to improve soil health and productive capacity, our results indicate the importance of identifying variability of subsoil characteristics to address long-term impacts on soil erosion and productivity. Keywords: Soil erosion, Soil electrical conductivity, Claypan soil, Productive capacity, Electrical resistivity tomography.

Soybean Yield Variability of Drainage and Subirrigation Systems in a Claypan Soil

Abstract. Claypan soils with less than 1% slope are poorly drained because of an argillic claypan layer 45 to 60 cm below the soil surface. Field research was conducted near Bethel, Missouri, to evaluate soybean ( [L.] Merr.) grain yields and plant populations above subsurface drain tile lines and 3.1 m distances from the tile lines of laterals installed at 6.1 and 12.2 m wide spacings for drainage (DO) or drainage plus subirrigation (DSI). The site was arranged as a split-plot design with four replications. In some years, sub-sub-plots included multiple cultivars or fungicide/insecticide management systems. This resulted in 30 year-cultivar-management (YCM) treatments from 2002 to 2015. Averaged over all of the 30 YCM systems, the highest yields (4,050 kg/ha) were observed above the 6.1 m DSI drainage tile line. Subsurface drainage tile spacings (6.1 and 12.2 m) and distances from the tile lines for DO or DSI yielded 11% to 21% greater than the ND control. Due to extreme weather events among YCM systems, data were separated into low (LYE, <3,360 kg/ha) and high (HYE, >3,360 kg/ha) yield environments. In LYEs, yields were more variable above the tile line and generally decreased as the distance from the subsurface tile lines increased for DSI, but yields were greater and more variable between the tile lines for DO. In HYEs, yields were greatest and more variable between the 6.1 or 12.2 m spaced DO treatments, while yields were greatest above the drain tiles with lower variability compared to between the tile lines with DSI. A narrower drain tile spacing may be needed to reduce yield variability in LYEs, but this was less evident in HYEs. Keywords: Claypan, Drain tile spacing, Drainage, Subirrigation, Water management.

Response of Soybean Grown on a Claypan Soil in Southeastern Kansas to the Residual of Different Plant Nutrient Sources and Tillage

Response of Soybean Grown on a Claypan Soil in Southeastern Kansas to the Residual of Different Plant Nutrient Sources and Tillage

Inversion of soil electrical conductivity data to estimate layered soil properties

Bulk apparent soil electrical conductivity (ECa) sensors respond to multiple soil properties, including clay content, water content, and salt content (i.e. salinity). They provide a single sensor value for an entire soil profile down to a sensor-dependent measurement depth, weighted by a nonlinear response function. Because of this, it is generally difficult to elucidate strong relationships between ECa and the measured properties of individual soil layers. This research investigated inversion of the equations that govern the ECa-depth response relationship to reconstruct the soil conductivity in profile layers using data collected in multiple fields in the Midwest US. Layer conductivities obtained by inversion were first validated by comparison with true conductivities measured as a function of depth with an ECa-sensing penetrometer. Then, the validated layer conductivities were related to laboratory- measured soil properties. Inversion worked well but sometimes required iterative adjustment of initial conditions and other input parameters to obtain best results. Strong linear relationships (r2≥0.76) were obtained between inversion-estimated and measured layer conductivity data in all cases, sometimes with a truncated depth range. Layer conductivity data was successfully used to estimate soil texture fractions in the two alluvial fields examined. This was not the case for a claypan soil field, where there appeared to be parameters other than texture strongly affecting the EC response. Further examination of this approach is warranted to potentially provide improved ways to estimate depth-variable soil properties using ECa.

Nitrogen Management for Seed Production from Endophyte-Free Tall Fescue Grown on Claypan Soil

Core Ideas Pastures may be replanted with endophyte-free seed to avoid harmful alkaloids. Better N management may be required for endophyte-free fescue seed production. Nitrogen fertilizer placement has little effect on endophyte-free seed production. Fescue seed yield may be maximized with 150 lb N/acre applied in late winter. Nitrogen fertilization affects tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] forage production, but data are limited regarding seed production from endophyte-free tall fescue grown on the claypan soils of the eastern Great Plains. A field study was conducted from fall 1998 to spring 2001 to determine the effects of N fertilizer timing (late fall or late winter), N placement (surface broadcast, spoke [point injection at 3 inches deep], and knife [subsurface band at 4 inches deep]), and N rate (0, 50, 100, 150, and 200 lb/acre) on endophyte-free tall fescue seed yield, yield components, and harvested seed germination. The soil was a Parsons silt loam (fine, mixed, thermic Mollic Albaqualf), which is a typical claypan soil of the area. Seed yield response to N rates to 100 lb N/acre was similar regardless of application timing, but in two of three years, greater N rates applied in late fall improved seed production to about 400 lb/acre. Even though all components of seed yield responded to N fertilization, panicles/ft2 had the highest correlation (r = 0.83) with seed yield and showed greater response in 1999 to N applied in late fall at a higher rate compared with fewer panicles/ft2 at lower rates of N applied in late winter. The effect of N fertilization on germination of harvested seed was small. Fertilizer N placement had little effect on measured variables. In summary, increasing N rate to 150 lb/acre and applying it in late winter has the potential to maximize production of endophyte-free tall fescue seed.

Does 20 Years of Tillage and N Fertilization Influence Properties of a Claypan Soil in the Eastern Great Plains?

Core Ideas Claypan soil properties were minimally affected by tillage and N fertilization after 20 years. Soil organic matter distribution was affected by tillage, but with no apparent net difference. Long‐term tillage and N fertilization did not affect soil bulk density or penetration resistance. Subtle long‐term soil changes may not influence producer choices for tillage and N fertilization. Tillage and nitrogen (N) fertilization systems may affect soil chemical and physical properties, especially long term. This study's objective was to examine the effect of three tillage systems (conventional tillage, reduced tillage, and no‐till) with four N fertilizer treatments on properties of a claypan soil in the eastern Great Plains after 20 yr of cropping. Soil chemical and physical properties were little affected by long‐term tillage and N fertilization. The lack of tillage to distribute soil phosphorus (P) and potassium (K) nutrients within no‐till treatments resulted in lower P and K values below the surface. In no‐till, the accumulation of organic matter in the surface soil (0 to 7.5 cm) was countered by lower organic matter in the 7.5‐ to 15 ‐cm zone, resulting in no net increase compared with the other two tillage systems. Soil bulk density and penetration resistance in the surface 30 cm were unaffected by tillage or N fertilization.

Urea Fertilizer Placement Impacts on Corn Growth and Nitrogen Utilization in a Poorly-Drained Claypan Soil

<p>Practices to increase nitrogen (N) use efficiency (NUE) include selecting appropriate N fertilizer sources and application methods, but minimal research has focused on these practices in poorly-drained claypan soils which are prone to N loss. This research assessed the impact of different urea fertilizer placement practices on corn (<em>Zea mays</em> L.) production and N utilization in a poorly-drained claypan soil. Field trials were conducted in 2014 and 2015 in Missouri. Treatments consisted of pre-plant deep banding (20 cm) urea at 202 kg N ha<sup>-1</sup> or urea plus a nitrification inhibitor (NI) (nitrapyrin) compared to pre-plant urea broadcast surface-applied or incorporated to a depth of 8 cm. In 2014, incorporating urea, deep banding urea, and deep banding urea plus NI had higher yields (> 10%) of corn compared to the control with grain yields ranging from 13.73 to 14.05 Mg ha<sup>-1</sup>. In 2015, grain yields were lower than in 2014, ranging from 4.1 to 7.9 Mg ha<sup>-1</sup>. Deep placing banded urea with a NI yielded an increase in grain yield up to 48% compared to the other treatments. Rainfall amounts were higher in 2015, which could have resulted in poorer root growth and greater N loss in deep banded treatments. In 2014, deep banding urea with a NI produced the highest NUE. Similar to NUE, silage tissue N concentrations in 2014 were greater with deep banded urea plus NI, while in 2015 silage tissue N concentrations were higher with surface applied urea. The results suggest that urea fertilizer incorporation including deep banding may improve corn grain production, N uptake, and NUE, but response was affected by climatic conditions. The addition of an NI may be an important safeguard when deep banding urea in years with excessive precipitation.</p>

Soil water infiltration affected by topsoil thickness in row crop and switchgrass production systems

Conversion of annual grain crop systems to biofuel production systems can restore soil hydrologic function; however, information on these effects is limited. Hence, the objective of this study was to evaluate the influence of topsoil thickness on water infiltration in claypan soils for grain and switchgrass (Panicum virgatum L.) production systems. The experiment was performed at the University of Missouri South Farm (38°54′N, 92°16′W) on a Mexico silt loam (Vertic Luvisols) soil. Since 2009, plots were planted with either switchgrass or a corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation. Infiltration rates were measured using ponded infiltrometers during two years (2014 and 2015) under switchgrass and grain crop management each with two levels of topsoil thickness (0 and 37.5cm). Physically-based Parlange and Green-Ampt infiltration models were used to estimate saturated hydraulic conductivity (Ks) and sorptivity (S) parameters. Switchgrass planted on degraded soil (shallow topsoil treatment) resulted in greater Ks, S, qs (quasi-steady infiltration rate) and Kfs (field-saturated hydraulic conductivity) values than with row crop management for both 2014 and 2015 measurement years. Results for selected 24-hour mean frequency (11.8, 14.2, and 16.2cm) storms showed that switchgrass production systems enhanced estimated water infiltration, reduced estimated runoff, and decreased estimated time from water ponding to end of ponding compared with row crop management. Switchgrass is recommended to be planted on degraded soils especially in claypan landscapes for improved water use.

Limited Irrigation for Sweet Corn Planted at Different Dates on Claypan Soil

Irrigation sources in the claypan soil areas of the eastern Great Plains are limited, but supplemental irrigation at certain growth stages may help lessen crop stress. The objective of this research was to determine the effect of critically timed, limited‐amount irrigation on yield and growth of sweet corn (Zea mays L.) planted at two dates with different levels of N fertilization. During the three years of this study, planting date influenced both the total number and total fresh weight of harvested sweet corn, but the effect of early and late plantings was not consistent. Early plantings resulted in up to 65% more harvested ears, nearly twice the total fresh weight yields, and increased number of ears/plant and individual ear weight, especially when plantings were delayed in one year because of inclement weather conditions. But early plantings also can result in lower production when rainfall is great and temperatures are cool. Although irrigation at the V12 and R1 growth stages was found to improve sweet corn yield by as much as 30% over no irrigation, especially when planted late, droughty conditions were not prevalent at the site used in this study and the benefit was sporadic with few differences between irrigation timings. On this site, N fertilization rates had little effect on sweet corn production. Growth of sweet corn was mainly affected by planting date, but dry matter produced during the season was not a consistent indicator of yield.

Soil hydraulic properties as influenced by prairie restoration

Prairie restoration has received increased public attention in recent years for its ecosystem services. The objective of this study was to evaluate effects of prairie restoration on soil hydraulic properties as compared to native prairie (NP), grass and row-crop management. Soil cores (76mm diam.×76mm long) from six replicate locations were sampled to a 60-cm depth at 10-cm intervals from two prairie treatments, a continuous no-till treatment (NT), a long-term timothy grass (Phleum pratense L.) treatment (TM) and a row-crop (RC) treatment. The NP has never been tilled and the restored prairie (RP) was established in 1993. All treatments have Mexico silt loam (fine, smectitic, mesic, Vertic Epiaqualfs) soil. Bulk density, saturated hydraulic conductivity (Ksat), soil water retention and pore size distribution were determined. In-situ Ksat was measured using a constant head permeameter with five replications. Bulk density was significantly lower for NP than all treatments. Bulk density was significantly lower for the 0 to 10cm depth for all treatments, and the 10 to 30cm depth recorded the highest values. The in-situ Ksat of RP was lower than other treatments. The first horizon had the highest value for this parameter for all treatments. NP had significantly higher laboratory measured Ksat, and it was almost four times higher than RP. The 0 to 10cm depth of all treatments had significantly higher values for laboratory Ksat than other depths and the 50 to 60cm showed the lowest Ksat. NP had the highest macroporosity and fine-mesoporosity, while RP had the highest microporosity. NP had significantly higher water retention at saturation while RP had the highest water retention for soil water pressures of −33kPa, −100kPa and −1500kPa. Soil water retention was significantly higher in NP for −0.4kPa to −10kPa soil water pressures; at −20kPa NP, RP and RC had significantly higher water retention. The NP treatment had higher soil water content than the other treatments for the 0 to 10cm, 10 to 20cm, 20 to 30cm and 50 to 60cm depths at soil water pressure of −20kPa. The 30 to 40cm and 40 to 50cm depths of RP had higher soil water content at all soil water pressures. Results imply that prairie restoration influences some hydraulic properties in claypan soils; however, it is unlikely to achieve the original prairie soil characteristics due to the prior erosion of the top soil.

Tillage, Seeding Rate, and Fertilizer Placement for Corn Grown in Claypan Soil under Low‐yielding Conditions

Environmental and economic concerns lead producers to consider conservation tillage systems. However, the lower yield often associated with corn (Zea mays L.) grown without tillage on the claypan soils of the eastern Great Plains may encourage alternative conservation tillage systems and management options. The objective of this study was to determine optimum seeding rates and fertilizer placement to improve production of corn grown in strip‐till and no‐till systems as compared with conventional tillage (chisel plow and tandem disk) on claypan soil in southeastern Kansas. Corn production was affected by tillage, fertilizer placement, and seeding rate even under low‐yielding conditions, but responses varied by site. At one site during low‐yielding conditions, conventional tillage improved yields by 28% above those obtained with no‐till with strip‐till providing intermediate yields, likely because of tillage influence on plant stand. Even though subsurface band (knife) fertilizer application improved corn yield by about 10 to 15% compared with surface band (dribble) fertilizer application, primarily due to increasing kernel weight and the number of kernels/ear, the response was more prominent in years not affected by severe drought. Increasing seeding rates from 18,000 to 34,000 seeds/acre increased plant populations, but under poor growing conditions increases in seeding rates often depressed the number of ears/plant, kernel weight, and the number of kernels/ear. Even though environmental conditions are unpredictable, seeding rates >22,000 seeds/acre on claypan soils may only provide potential yield increases under higher‐yielding environments than encountered in this study.

Validating the Soil Vulnerability Index for a claypan watershed

Assessment studies of conservation efforts have shown that best management practices were not always implemented in the most vulnerable areas where they are most needed. While complex computer simulation models can be used to identify these areas, resources needed for using such models are beyond reach for most water resources managers. Soil and water conservationists need simple, spatially explicit tools such as the USDA-NRCS's Soil Vulnerability Index (SVI) to evaluate the inherent vulnerability of soils and the risk they pose to water quality when used for row crop agriculture. In this study, the SVI was evaluated in the Goodwater Creek Experimental Watershed (GCEW), a claypan watershed in Missouri, using three methods: professional judgment, comparison to the Conductivity Claypan Index (CCI) developed specifically for claypan soils, and comparison to model results. Factors affecting the critical areas identified by each method were assessed and classified areas were compared. Slope and depth to claypan had the most variability in GCEW and were found to be influential in determining area classification by each index. While the original definition of SVI included the soil type representative slope from the USDA SSURGO database, slope values provided by a Digital Elevation Model (DEM) improved the index usefulness by classifying visibly degraded and non-degraded areas in different categories. High and moderately high vulnerability areas identified with SVI, CCI and model results with DEM slopes were consistent and matched professional judgment. Additional testing of SVI is recommended in areas characterized by soils of different permeability and under different climates.

Long‐Term Impacts of Cropping Systems and Landscape Positions on Claypan‐Soil Grain Crop Production

Sustainable grain crop production on vulnerable claypan soils requires improved knowledge of long‐term impacts of conservation cropping systems (CS). Therefore, effects of CS and landscape positions (LP) on corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and wheat (Triticum aestivum L.) production were evaluated from 1991 to 2010 on a claypan soil in Missouri. Replicated treatments were three CS (2‐yr mulch till corn–soybean [MTCS], 2‐yr no‐till corn–soybean [NTCS], and 3‐yr no‐till corn–soybean–wheat–cover crop [NTCSW]) and three LP (summit, backslope, and footslope). Corn yield was equivalent among CS on the summit, 13% higher for NTCS and NTCSW on the backslope, and 14% lower for NTCSW on the footslope. Soybean yield was 8% higher on the summit, 24% higher on the backslope in NTCS and NTCSW, and 12% higher on the footslope in NTCSW than MTCS. Corn yield was more stable in NTCS and NTCSW than MTCS and increased in stability from the footslope to summit. Soybean yield was less stable in NTCS and NTCSW than MTCS and LP effects on stability were similar to corn. The coefficient of variation (CV) of corn yield across years was 10% points lower in NTCS and on the footslope, and of soybean yield was 10% points lower at the footslope and summit. Wheat production was not affected by LP. Results indicate that conservation systems often can maintain grain crop productivity equal to, increase yield stability above, and reduce yield variability below those of a conventional system on claypan soils.

Controls on nitrate‐N concentrations in groundwater in a Missourian claypan watershed

AbstractNitrogen (N) fertilizer applications have resulted in widespread groundwater nitrate‐N (NO3‐N) contamination in the U.S. Corn Belt. Goodwater Creek Experimental Watershed (GCEW) is an agricultural watershed in the claypan soil region of northeastern Missouri with a network of 96 wells at depths of 2.7–15.7 m. The objectives of this study were to (1) inspect the spatial and temporal variations of NO3‐N concentrations in GCEW's groundwater, particularly with well depth at scales ranging from individual well, well nest, and field to the entire watershed during the period 1991 to 2004; (2) understand the processes controlling the variability of NO3‐N concentrations in groundwater at various scales within GCEW; and (3) compare groundwater NO3‐N concentrations in GCEW to other agricultural watersheds in the U.S. Nitrate‐N concentrations were determined in more than 2000 samples collected from 1991 to 2004. Despite the low hydraulic conductivity of the claypan soils, considerable NO3‐N contamination of the glacial till aquifer occurred, with 38% of the wells exceeding 10 mg L−1. Groundwater recharge by preferential pathways through the claypan appeared to be the primary mechanism for NO3‐N movement to the aquifer. Changes in concentration with depth steadily increased to 8.5–10 m and then decreased with further depth. This pattern was consistent with decreased hydraulic conductivity in the Paleosol layer at 8.5–10 m, denitrification below this layer, and mixing of recent contaminated water with older uncontaminated water in the lowest strata. Only 19–23% of sampled wells exceeded 10 mg L−1 in nonclaypan agricultural watersheds over the continental U.S., suggesting that groundwater in GCEW was more susceptible to NO3‐N contamination than nonclaypan watersheds. These results demonstrated that preferential flow through the soil and hydraulic conductivity of the subsurface strata controlled NO3‐N transport in this claypan watershed.

Impact of rhizome quality on Miscanthus establishment in claypan soil landscapes

Thousands of eroded-soil hectares in the U.S. Midwest have been planted to Miscanthus×giganteus as an industrial or bioenergy crop in recent years, but few studies on factors affecting crop establishment have been performed on these soils. The objective of this study was to quantify how both rhizome quality and depth of soil from the surface to the first argillic horizon (or depth to claypan (DTC11DTC—depth to claypan or argillic horizon.)) affected M.×giganteus establishment. Rhizome quality (i.e., mass, length, diameter, viable buds, score), emergence, growth, and winter survival were measured on rhizomes planted in 2013 at Columbia and 2014 at Centralia, Missouri on clay loam soils with a range of DTC. Rhizome emergence and early tillering slightly increased as DTC increased, but these effects on growth diminished as the season progressed. Rhizome emergence and growth were more influenced by some metrics of rhizome quality; the odds of a rhizome emerging increased by 25 and 40% with each 1cm and 1 bud increase in rhizome length and active bud count, respectively. Furthermore, late tiller counts, basal circumference, and end-of-season biomass increased as rhizome length and mass increased. Winter survival could not be estimated as well as emergence, but the odds of survival across sites increased by 5% with each 1cm increase in rhizome length. When DTC was categorized as soil erosion class or landscape position, only the backslope at Centralia caused greater M.×giganteus growth than other positions. These findings demonstrate the resiliency of M.×giganteus for early growth and establishment on even the most degraded parts of the claypan soil landscape and indicate that propagating larger rhizomes will improve establishment.

Water infiltration and soil water content in claypan soils influenced by agroforestry and grass buffers compared to row crop management

Agroforestry buffers have recently been introduced in temperate regions to enhance conservation of soil and water resources in row crop management. The effects of agroforestry and grass-legume buffers on in situ water infiltration relative to row crop management (RC) were assessed for a claypan soil in northeastern Missouri, USA. Infiltration rates were observed in early June in 2014 and 2015 for watersheds under corn (Zea mays L.)-soybean (Glycine max L. Merr.) management; these watersheds had agroforestry buffers (AGB) or grass buffers (GB). The dominant soil for the watersheds was Putnam silt loam (fine, smectitic, mesic Vertic Albaqualf). The watersheds were in no-till management and established in 1991 with agroforestry buffers and GBs implemented in 1997. Agroforestry buffers, 4.5 m wide and 36.5 m apart, consisted of redtop (Agrostis gigantean Roth), brome (Bromus spp.), and birdsfoot trefoil (Lotus corniculatus L.) with pin oak (Quercus palustris Menchh.), swamp white oak (Q. bicolor Willd.), and bur oak (Q. macrocarpa Michx.) trees. GBs consisted of redtop, brome, and birdsfoot trefoil. Significant differences were found among the treatments in 2014 for the sorptivity parameter for the fitted infiltration equations with the highest values for agroforestry buffers. Significantly higher saturated hydraulic conductivity values were found for the buffer treatments in 2015. Soil water content measurements were assessed over time for years 2010 and 2011 with sensors at 5, 10, 20 and 40 cm depths for the agroforestry buffer and RC areas. Water content decreased more rapidly during the summer season within agroforestry buffers relative to RC areas; however, water infiltration was higher within agroforestry buffers during the recharge period.

Fertilizer placement to maximize nitrogen use by fescue

ABSTRACTThe method of fertilizer nitrogen (N) application can affect N uptake in tall fescue and therefore its yield and quality. Subsurface-banding (knife) of fertilizer maximizes fescue N uptake in the poorly-drained clay-pan soils of southeastern Kansas. This study was conducted to determine if knifed N results in greater N uptake than the conventional top-dress application method in a deep, well-drained soil of east-central Kansas. The experiment, conducted in a Smolan silty clay loam soil, was a split-plot with fertilizer nitrogen rates 0, 140 and 280 kg N ha−1 applied as urea-ammonium nitrate (UAN, 28% N), knifed or top-dressed. Soil inorganic N [ammonium (NH4)- and nitrate (NO3–N)] and N in roots and plant tops were measured at various times during the growing season. At final harvest, most of the knifed N (99.7%) was accounted for in plant tissue (roots and tops) and soil, with more than half of the knifed N remaining as soil inorganic N. With the top-dressed method, 27% was unaccounted for and presumed lost in gaseous form. Knifing fertilizer N in fescue fields of east-central Kansas will maximize the availability of N, reduce potential N losses, and increase forage quality.

Response of Soybean Grown on a Claypan Soil in Southeastern Kansas to the Residual of Different Plant Nutrient Sources and Tillage

Response of Soybean Grown on a Claypan Soil in Southeastern Kansas to the Residual of Different Plant Nutrient Sources and Tillage

Response of Soybean Grown on a Claypan Soil in Southeastern Kansas to the Residual of Different Plant Nutrient Sources and Tillage

Response of Soybean Grown on a Claypan Soil in Southeastern Kansas to the Residual of Different Plant Nutrient Sources and Tillage