Bray P1 Research Articles

Calibration of Mehlich-3 with Bray P1 and Ammonium Acetate in the Tri-State Region of Ohio, Indiana and Michigan

ABSTRACT Field crop fertilizer recommendations for Ohio, Indiana and Michigan are currently based on the Bray P1 extractant for phosphorus (P) and the ammonium acetate extractant (AA) for base cations. The fertilizer recommendations in this Tri-State region are currently being revised and will use the Mehlich-3 soil test extractant as the new basis for P and potassium (K) fertilizer recommendations. The goal of this study was to document the relationships between Mehlich-3, Bray P1, and AA soil test extractants and to provide a comprehensive review of these relationships published in the literature. Soil samples (n = 2,659) were collected across Ohio and Indiana from a diverse range of fields and analyzed for Mehlich-3, Bray P1 and AA extractable nutrients for P, K, calcium (Ca), and magnesium (Mg). Mehlich-3 P values were highly related to, but 35% greater than Bray P1 values. Mehlich-3 values were highly related to AA values, but 14% greater than AA-K, 13% greater than AA-Ca and 20% greater than AA-Mg. Our results are largely consistent with a comprehensively compiled literature review that indicates Mehlich-3 is an efficient and suitable soil test extractant for assessing extractable nutrient levels in the Tri-State region of Ohio, Indiana and Michigan.

Manure Management at Ohio Confined Animal Feeding Facilities in the Maumee River Watershed

In 2015, 48 permitted Confined Animal Feeding Operations (CAFOs) housed approximately 90% of poultry and 20% of swine and cattle within the Ohio portion of the Maumee River watershed. Recently, concerns about the impact CAFOs may have on nutrient loading in the watershed have been raised. In this study, we used manure management plans and inspection reports obtained from the Ohio Department of Agriculture Division of Livestock Environmental Permitting (ODA-DLEP) to assess how these CAFOs managed their manure for the years 2014 and 2015. A majority of liquid manure was applied between April and October, closely matching the amount of liquid manure planned to be applied during this period. Approximately 79% of the acres under control of the CAFOs that received manure had Bray P1 soil test phosphorus values below 50 ppm. The average distance between a swine CAFO’s livestock holding barn to the fields they control that can receive manure was 1.43 miles while for cattle CAFOs this distance was 1.91 miles. Approximately 78% of manure phosphorus generated on CAFOs was planned to be transferred through Distribution and Utilization, a process in which ownership of manure changes hands, including virtually all solid poultry manure phosphorus. While publicly available data show that, in general, CAFOs in the region are adhering to their state-approved permits, a knowledge gap regarding the management of approximately 80% of manure phosphorus exists due to manure transferred through Distribution and Utilization and manure produced from non-permitted livestock operations.

Assessing microbial population dynamics, enzyme activities and phosphorus availability indices during phospho-compost production

PurposeThis study assessed changes in bio-quality indices and plant available P released during aerobic–thermophilic co-composting of different mix ratios of non-reactive ground phosphate rock (GPR) with poultry and cattle manures.MethodsAerobic–thermophilic co-composting of different mix ratios (5:5, 8:2, 7:3 and 9:1) of non-reactive GPR with poultry and cattle manures was carried out. Compost piles without GPR addition were included as control. Compost samples were taken at mesophilic, thermophilic, cooling–stabilization and maturing phases for microbial counts, enzyme activities and P assessment.ResultsAbundance of different microbial groups across the composting phases varied greatly (p < 0.001) mostly dominated by fungi that was generally more in the cattle than poultry manure-based phospho-composts. Fungi and actinomycetes counts in the composts were positively correlated with alkaline phosphatase and β-glucosidase. A strong inter-correlation between β-glucosidase and alkaline phosphatase (r = 1.000, p < 0.001) was observed, suggesting that both enzymes possess same origin. Alkaline phosphatase and β-glucosidase contents in the phospho-composts showed negative correlation with water soluble P (r = − 0.65, p < 0.001), and Bray P1 and Fe–P contents (r = − 0.15, p > 0.05) indicating inhibition of the P forms. Quantitatively higher P was obtained from poultry manure-based phospho-compost and in the 8:2 mix ratio at compost maturity. Microbial diversity and enzyme activity exerted positive impact on P mineralization and availability from the non-reactive GPR signifying the beneficial effect of co-composting.ConclusionsCo-composting of P-rich non-reactive GPR with organic wastes containing variable chemical composition promotes microbial diversity during composting and increases plant available P content and compost fertilizer value.

Use of Routine Soil Tests to Estimate Pb Bioaccessibility.

Soil lead (Pb) hazard level is contingent on bioavailability, but existing assays that estimate Pb bioavailability for human health risks are too expensive or otherwise inaccessible to many people that are impacted by Pb-contaminated soil. This study investigated the use of routine soil nutrient tests to estimate soil-Pb bioaccessibility as a surrogate measure of Pb bioavailability. A silt loam soil was spiked to a target concentration of 2000 mg Pb kg-1 with Pb(NO3)2 and amended with H3PO4 (varying P-to-Pb molar ratios) and KCl (Cl-to-P molar ratio of 2:5) to generate soils with similar total Pb concentrations but a range of Pb bioavailability (and bioaccessibility). Soils were extracted using Mehlich 3, Mehlich 1, Bray P1, Olsen, andmicronutrient (DTPA) methods, and the results were compared to U.S. Environmental Protection Agency method 1340 data as well as to extended X-ray absorption fine structure (EXAFS) spectroscopy. The Mehlich 3 and method 1340 treatment effect ratios were well-correlated ( r2 = 0.88, p ≤ 0.05), whereas Bray P1, DTPA, and Olsen results were more reflective of EXAFS data. Preliminary animal-feeding trials suggest that the Mehlich 3 is as effective as method 1340 at predicting the impact of P treatment on Pb relative bioavailability; however, both methods over-estimated the Pb hazard to mice in P-amended soil. Other routine soil tests that have heightened sensitivity to P amendment (e.g., Bray P1) may be promising candidates for Pb bioaccessibility assessment.

Evaluation of multi-nutrient extractants for determination of available P, K, and micronutrient cations in soil

ABSTRACTSixty soil samples (0–0.15 m depth) collected randomly from different districts of Himachal Pradesh were used to evaluate ammonium bicarbonate-diethylenetriaminepenta acetic acid (AB-DTPA) and acid ammonium acetate-ethylene diamine tetra acetic acid (AAAc-EDTA) over standard methods for P, K, and micronutrient cations. Among Olsen P, Bray P1, AB-DTPA P, and AAAc-EDTA P, available P (kg ha−1) varied from 7.8 to 44.3, 9.5 to 61.1, 6.5 to 38.8, 10.5 to 52.1; available K (kg ha−1) among NH4OAc, AB-DTPA, and AAAc-EDTA ranged from 103.6 to 372.3, 86.6 to 364.9, and 74.6 to 362.5. In case of micronutrients cations, AB-DTPA in general, extracted more amounts as compared to DTPA alone. AAAc-EDTA correlated highly with the Olsen P. AB-DTPA-K and AAAc-EDTA-K correlated well with standard method (NH4OAc) however; AAAc-EDTA had higher correlation with AB-DTPA for K extractability. Among methods for micronutrients highest significant correlations were observed between AB-DTPA and DTPA for Cu, Fe, and Zn.

Evaluation of Spatial Variability of Soil Physico-Chemical Characteristics on Rhodic Ferralsol at the Syferkuil Experimental Farm of University of Limpopo, South Africa

&lt;p&gt;Spatial variability among selected soil physical and chemical properties in twelve profiles dug across the research block of the University of Limpopo experimental farm was investigated. The soils were moderately shallow to deep, contain variable textural classes and classified as Rhodic ferralsol. Over 90% of the samples were considered as slightly alkaline based on the water-measured pHvalues but decreased to marginally over 27% when measured in KCl. The electrical conductivity of the soils revealed a generally non-saline field. Bray P1, EC, exchangeable cations, extractable Zn and effective cation exchange capacity contents differed significantly (p &amp;lt; 0.05) with depth while K, Mg, Ca, Mn, organic carbon and ECEC differed significantly (p &amp;lt; 0.05) across profiles. Semi-variograms for the measured variables had low values indicating the existence of considerable level of spatial variability. Spatial dependence among top and subsoil pH, EC, organic carbon, sand, silt clay and bulk density ranged between weak and strong. Results revealed a significant spatial variability of the characterized parameters across the research block because to differences in tillage, cropping pattern and nutrient specific application over the years.&lt;/p&gt;

English

Evaluation of nutrient status in soil is important for nutritional, environmental and economical aspects. Phosphorus is a very important nutrient for leguminous crops. In order to evaluate the phosphorus availability, six soil test methods were carried out for predicting response of soybean to phosphorus application on twenty surface soils (0 - 15 cm) of Imphal East District, Manipur were studied. The suitability of these extractants was in the descending order: Bray P1 &gt; Mehlich P1 &gt; Bray P2 &gt; Troug P &gt; Olsen P &gt; Morgan P. Bray&rsquo;s P1 extractable phosphorus showed the highest and positive correlations with phosphorus content (control), phosphorus uptake (control), Bray&rsquo;s percent yield and uptake. Therefore, this extractant may be used as an index of available phosphorus for soybean (JS-335) grown on acid soils of Imphal East District, Manipur, the critical level being 13 ppm (mg kg-1). The critical limit of phosphorus concentration in plant at 40 days of planting was 0.22%. &nbsp; Key words: Phosphorus, acid soils, Bray&rsquo;s percent yield, soybean, critical limit.

Beef Cattle Manure Survey and Assessment of Crop Availability of Phosphorus by Soil Testing

Knowing beef cattle (Bos taurus) manure P crop availability is essential to improve the utilization of this nonrenewable resource. This study surveyed cattle manure properties and evaluated its P crop-availability by soil testing. Manure samples were collected from 107 confined operations and classified into the types with bedding (BEDDED), concrete floor (CONCRETE), dirt floor (DIRT), no feeding of corn (Zea mays L.) coproducts (NoCCP), and liquid (PIT). Total P (TP) and the percentage water-soluble P of TP (MWSP%) were higher for BEDDED, CONCRETE, and PIT (10, 11, 15 g TP kg⁻¹ and 59, 57, and 55% MWSP) than for DIRT and NoCCP (5 and 7 g TP kg⁻¹, and 21 and 42% MWSP). Eleven representative samples from each manure type and di-ammonium phosphate (DAP) were incubated (1, 2, 5, 9, 14, and 23 wk) with soils Adair (fine, smectitic, mesic Aquertic Argiudolls), Harps (fine-loamy, mixed, superactive, mesic Typic Calciaquolls), and Nicollet (fine-loamy, mixed, superactive, mesic Aquic Hapludolls) by applying P equivalent to 87 kg TP ha⁻¹. After 1 wk of incubation, there were not significant or small and inconsistent soil P increases as measured by Bray-P1 (BP), Mehlich-3 (M3P), Olsen (OP), and water-extractable P (WEP). Manure P efficiency relative to DAP differed among P methods (80, 79, 77, and 74% for OP, M3P, BP, and WEP) and soils (84, 76, and 73% for Harps, Nicollet, and Adair). On average, manure P efficiency relative to DAP was 84 and 85% for BEDDED and CONCRETE manure, 77 and 74% for PIT and DIRT manure, and 69% for NoCCP manure.

Optimizing Phosphorus Fertilizer Management in Potato Production

Management of fertilizer phosphorus (P) is a critical component of potato production systems as potato has a relatively high P requirement and inefficiently uses soil P. Phosphorus promotes rapid canopy development, root cell division, tuber set, and starch synthesis. Adequate P is essential for optimizing tuber yield, solids content, nutritional quality, and resistance to some diseases. Although soil test P is the primary tool for assessing P fertilizer needs, in some areas petiole P analysis has been successfully utilized to guide in-season P applications. Potato has been shown in some studies to respond to fertilizer P at soil test levels considered very high for most other crops (100+ mg kg−1 Bray P1 or Mehlich I or III and 20+ mg kg−1 sodium bicarbonate) especially on medium- to finer-textured soils. Even on high-testing soils, fertilizer P rates for top yields sometimes exceed 150 kg P2O5 ha−1. In addition, many states/provinces continue to recommend half or more of the amount of P in the harvested portion of the crop irrespective of soil test P level. In most situations, few differences are expected among fertilizer P sources; however, high rates of diammonium phosphate (DAP) or urea-phosphate (UAP) should not be band-applied in contact or near the seed piece. Most research determined that fertilizer P was most efficiently used when band-applied at planting (e.g., 5 cm to each side of the seed piece); however, some western USA work on high-pH soils showed increased yields and petiole P levels with preplant broadcast applications. In-season applications with the irrigation water can be successful when the potato roots are sufficiently close to the soil surface; however, most research indicates that P applications are more effective when applied at planting or early in the season. Potato fertilizer phosphorus best management practices include: (1) apply the fertilizer P rate calibrated for local soils; (2) band-apply fertilizer P at least 5 cm from the seed piece, especially on very sandy soils or where DAP or UAP are used; (3) use petiole P tests to determine the need for in-season applications; (4) account for all P sources applied, including animal manures; and (5) utilize the best soil conservation practices to reduce P losses to surface waters.

Phosphorus status of some Malawi soils

Investigations conducted on Malawi soils ranging from highly weathered to less weathered soils show that P build-up due to fertilisation is much higher in soils managed by commercial estates than in soils managed by smallholder farmers. This suggests a need to monitor potential environmental impacts of the P build-up in the soils. The P build-up may be monitored using soil P tests used as a basis for P fertilisation. The present investigations have shown that the efficacy of selected soil tests in predicting P uptake was in the following increasing order: Olsen P > Nelson P > Bray P1=Resin P > Mehlich 3 > (0.5pCa + pH2PO4)eq. However, when potentially mineralisable soil organic P was included in the regressions of P uptake on each of the soil P tests, the accuracy of the soil tests was in the following increasing order: Bray P1 > Olsen P > Mehlich 3 > Nelson P > Resin P > (0.5pCa + pH2PO4)eq. The effectiveness of Bray P1 extraction method may be attributed to the acidic nature of the extractant (pH 2.6), which increases the activity of phosphate ions in soil solutions following dissolution of Ca-, Al-, and Fe-bound P forms and both the complexation of Al and Fe by humic substances and the precipitation of Ca (CaF2) by the fluoride (F−) component of the extractant. Mehlich 3 is used in Malawi as a basis for P fertilisation. It could also be used for monitoring potential environmental impacts of P build-up in Malawi soils. Key words: Phosphorus status, extractants, ferruginous oils, ferralitic oils, alluvial soils, potentially mineralisable soil organic P.

Serpentine affected soils and the formation of magnesium phosphates (struvite)

Baugé, S. M. Y., Lavkulich, L. M. and Schreier, H. E. 2013. Serpentine affected soils and the formation of magnesium phosphates (struvite). Can. J. Soil Sci. 93: 161–172. The Sumas River watershed, located in the intensive agricultural region of the Lower Fraser Valley of British Columbia (Canada), contains serpentine asbestos from a natural landslide. Serpentinic soils have a high Mg to Ca ratio that can affect soil fertility, including soil-solution P relations. The objectives of the study were: (i) to evaluate some common methods of estimating plant available phosphorus in the surface horizons of the serpentine-affected soils and those receiving large quantities of livestock manure, and (ii) to determine if there is evidence for the formation of soluble Mg phosphates, e.g., struvite, a meta-stable P phase in these soils. Seven soil nutrient extractants were used to determine major and minor elemental concentrations. Acid ammonium oxalate, 1 M HCl and Bray P1 extractions were most effective for measuring available phosphorus in these soils. Manure and fertilizer applications appear to favor the formation of Mg-phosphates, and are considered to be more soluble in terms of phosphorus than either calcium-phosphates or aluminum/iron-phosphates. X-ray diffraction, scanning electron microscopy and nuclear magnetic resonance examinations gave positive evidence for the presence of struvite in the soils.

Soybean Yield and Quality in Relation to Soil Properties

To optimize management, farmers require quantitative understanding of the factors affecting variability in soybean [Glycine max (L.) Merr.] seed yield and quality. Our objectives were to characterize spatial variation in soybean seed yield, oil concentration, and protein concentration in two south‐central Minnesota fields over 6 yr of a corn [Zea mays L.]–soybean rotation, and to determine the influence of fertilizer treatments, soil chemical properties, and topography on soybean yield, oil, and protein. Soil and topographical variables were observed on 0.014‐ha cells, and included Bray P1, Olsen P, K, Zn, pH, organic matter, total organic C, NH4–N, NO3–N, total N, mineralizable N, elevation, slope, curvature, flow accumulation, and aspect. Soybean yields consistently exhibited spatial structure. Within fields, spatial patterns of soybean yields were highly correlated across years, and we observed consistent relationships between yield and soil variables. Overall, soybean yield related positively to soil P and Zn and negatively to pH at all site‐years. Models of soybean yield in relation to soil P and Zn indicate that in high pH soils at these sites, yield is optimized when soil P and Zn levels are higher than current extension recommendations. Protein and oil concentrations exhibited inconsistent spatial structure, and the spatial pattern of protein and oil concentrations differed across years. Relationships between soybean quality and soil properties were more consistent between sites within years than across years within sites, indicating that soybean quality is influenced by soil–climate interactions that function on a regional basis.

Influence of Recent Acidification on Available Phosphorus Indices and Sorption in Washington State Soils

Gradual soil acidification in the Columbia Basin (CB), Washington State, brings into question the validity of the traditional sodium bicarbonate (NaHCO₃) extractable P (Olsen phosphorus, OP) method for making fertility recommendations. Our objectives were to determine how soil pH influences the soil P indices after fertilization and sorption capacity of soils with similar levels of available P at varying soil pH levels. Collected soils represented a range of pH (5.2–8.4) and OP (3–40 mg P kg⁻¹). Soils were treated with 0, 44, 88, or 132 kg P ha⁻¹ and incubated at 20°C for 6 wk. Subsamples were collected and analyzed for available P with OP, Bray P1 (BP1), modified Morgan (MMP), Mehlich-III (M3P) extractions. Additionally, P sorption isotherms were performed on untreated soils. Analysis of variance indicated that the slope of the change in extractable P was generally not significant (α = 0.05) for OP, BP1, MMP, and M3P given a P addition for several soils at different pH but of similar initial available P levels. Grouping soils by pH showed differences in slope with OP (0.27–0.34) yielding the least difference and MMP (0.12–0.33) the greatest related to soil pH. Langmuir parameters of b, sorption capacity, and k, binding energy, showed variability for soils grouped by initial available P for several pH levels. Grouped by pH there was little difference in P sorption in relation to soil pH. Continued use of OP on acidified soils of the CB appears to be a viable soil testing strategy.

Phosphorus Lateral Movement through Subsoil to Subsurface Tile Drains

Little research has focused on lateral P transport through subsoil to subsurface tile drains. We investigated P lateral movement through 3.0 m of an Iowa subsoil (1.6 g kg−1 Olsen P [OP], 157 g kg−1 clay) between two 1.07-m deep field trenches and a 1.0-m deep tile line. Well water was added to the trenches, and once the inflow rate equaled tile water outflow, a solution containing 8.7 mg L−1 P and 98 mg L−1 Br– tracer was added and maintained at a 0.6-m depth for 25 d. Most Br– tracer reached the tile, as the highest concentrations were 83 to 97 mg L−1 Br–, but little P reached the tile since the highest concentrations were 0.035 to 0.13 mg L−1 P. After draining the trenches, we measured subsoil OP and Bray-P1 (BP) from 0.60- to 0.75-, 0.75- to 0.90-, 0.90- to 1.05-, and 1.05- to 1.20-m depths of 22 vertical cores located between each trench and the tile line, and five 5-cm sections of three horizontal cores (0–0.25 m from the trench wall) taken from a 0.69-m depth. Subsoil P saturation was measured in selected samples. Subsoil P concentration and P saturation increased the most near the trench walls and decreased asymptotically to background levels at a 1- to 1.5-m distance from the trench wall. For instance, at a depth of 0.60 to 1.20 m, OP was 33 mg kg−1 and decreased to 2 mg kg−1. A typical P-deficient Iowa subsoil can limit the lateral movement of P from concentrated solutions toward tile drains, although continued P application can increase subsoil P levels and decrease P sorption.

Phosphorus Runoff from Turfgrass as Affected by Phosphorus Fertilization and Clipping Management

Phosphorus enrichment of surface water is a concern in many urban watersheds. A 3-yr study on a silt loam soil with 5% slope and high soil test P (27 mg kg(-1) Bray P1) was conducted to evaluate P fertilization and clipping management effects on P runoff from turfgrass (Poa pratensis L.) under frozen and nonfrozen conditions. Four fertilizer treatments were compared: (i) no fertilizer, (ii) nitrogen (N)+potassium (K)+0xP, (iii) N+K+1xP, and (iv) N+K+3xP. Phosphorus rates were 21.3 and 63.9 kg ha(-1) yr(-1) the first year and 7.1 and 21.3 kg ha(-1) yr(-1) the following 2 yr. Each fertilizer treatment was evaluated with clippings removed or clippings recycled back to the turf. In the first year, P runoff increased with increasing P rate and P losses were greater in runoff from frozen than nonfrozen soil. In year 2, total P runoff from the no fertilizer treatment was greater than from treatments receiving fertilizer. This was because reduced turf quality resulted in greater runoff depth from the no fertilizer treatment. In year 3, total P runoff from frozen soil and cumulative total P runoff increased with increasing P rate. Clipping management was not an important factor in any year, indicating that returning clippings does not significantly increase P runoff from turf. In the presence of N and K, P fertilization did not improve turf growth or quality in any year. Phosphorus runoff can be reduced by not applying P to high testing soils and avoiding fall applications when P is needed.

Diversity of Arbuscular Mycorrhizal Fungal Species in Soils of Cultivated Soybean Fields

Mycorrhizae are presumably important contributors to plant growth in most ecosystems. Our objective in this study was to evaluate the population diversity of arbuscular mycorrhizal (AM) fungi in Clarion (well drained) and Webster (poorly drained) soils of four Iowa soybean [Glycine max (L.) Merr.] fields. These soils normally occur together on the landscape, with Clarion in the upland and Webster in lowland positions. Previous work consistently has shown higher AM fungal spore counts in Webster soils. Spore morphology was used for the characterization of fungal species. Identification of certain species was confirmed using polymerase chain reaction (PCR)‐based rDNA fingerprinting. Glomus claroideum, G. etunicatum, G. mosseae, G. viscosum, and Paraglomus occultum‐like spores were prevalent in both Clarion and Webster soils. Trap cultures led to detection of several additional AM fungal species, including G. clarum, G. coronatum, G. fasciculatum, G. vesiforme, Acaulospora calossica, and Entrophospora infrequens The richness of the Glomus species varied from eight species in Webster soil of a field with highest available P (203 mg kg−1 soil Bray P1), where spores of G. mosseae constituted 90% of the spore population, to 12 species in Clarion soil, with lowest available P (14 mg kg−1 soil Bray P1). The variability of AM fungal density and distribution was also high among samples taken only 2 m apart. Although diverse within the genus, this study showed the dominance of Glomus species in field soils used to produce two important commercial crops, corn (Zea mays L.) and soybean, in the midwestern United States.

Turkey Manure Ash Effects on Alfalfa Yield, Tissue Elemental Composition, and Chemical Soil Properties

A power plant that utilizes turkey manure as fuel to produce energy was built in Benson, Minnesota, and started full energy production in 2007. The plant was built to meet legislative requirements governing the use of renewable sources to generate energy in Minnesota. Although the use of turkey manure as biofuel generates energy, it also results in turkey manure ash (TMA) as a by‐product that contains phosphorus (P), potassium (K), sulfur (S), and zinc (Z) as well as other essential and nonessential elements. A 2‐year study was conducted to compare TMA with triple‐superphosphate and potassium chloride fertilizers as a source of nutrients for alfalfa (Medicago sativa) at three locations: Lamberton, Morris, and Appleton, Minnesota. The soils at Lamberton and Appleton were acidic with P and K concentrations ranging from medium‐high to very high, whereas the soil at Morris was alkaline with high concentrations of P and K. The experiment consisted of a control (0 P and 0 K) and annual and split applications of TMA and fertilizer. Annual TMA and fertilizer rates were 84 kg P2O5 ha−1, 118 kg K2O ha−1, and 34 kg S ha−1. Split rates were 42/42 kg P2O5 ha−1, 59/59 kg K2O ha−1, and 17/17 kg S ha−1. However, because of an overestimation of citrate‐soluble P in 2005 for the TMA, the total amount of available P applied with the TMA for the 2‐year study was 168 kg P2O5 ha−1 compared with 286 kg P2O5 ha−1 for the fertilizer. In the first year, fertilizer resulted in greater alfalfa biomass yield than TMA and the control, whereas in the second year, alfalfa yields with TMA and fertilizer were similar and both more than the control. In 2005, TMA resulted in more copper (Cu) and S tissue concentrations than the fertilizer. In 2006, application of both sources increased tissue P and S concentrations compared with the control. The TMA increased tissue Cu concentration and Zn plant uptake compared with fertilizer. Bray P1–extractable soil P concentrations were less with TMA and control treatments than with the fertilizer treatments. Ammonium acetate–extractable soil sodium (Na) concentrations were greater with TMA than with fertilizer and the control. By the second year, both ash and fertilizer treatments resulted in more K uptake than the untreated control with no difference in K uptake between the two sources or time of application. Both sources were effective in increasing P uptake compared with the untreated control. TMA was shown to be an effective source of nutrients for alfalfa production.

Nutrient transport through a Vegetative Filter Strip with subsurface drainage

The transport of nutrients and soil sediments in runoff has been recognized as a noteworthy environmental issue. Vegetative Filter Strips (VFS) have been used as one of the best management practices (BMPs) for retaining nutrients and sediments from surface runoff, thus preventing the pollutants from reaching receiving waters. However, the effectiveness of a VFS when combined with a subsurface drainage system has not been investigated previously. This study was undertaken to monitor the retention and transport of nutrients within a VFS that had a subsurface drainage system installed at a depth of 1.2 m below the soil surface. Nutrient concentrations of NO 3-N (Nitrate Nitrogen), PO 4 − (Orthophosphorus), and TP (Total Phosphorus) were measured in surface water samples (entering and leaving the VFS), and subsurface outflow. Soil samples were collected and analyzed for plant available Phosphorus (Bray P1) and NO 3-N concentrations. Results showed that PO 4 −, NO 3-N, and TP concentrations decreased in surface flow through the VFS. Many surface outflow water samples from the VFS showed concentration reductions of as much as 75% for PO 4 − and 70% for TP. For subsurface outflow water samples through the drainage system, concentrations of PO 4 − and TP decreased but NO 3-N concentrations increased in comparison to concentrations in surface inflow samples. Soil samples that were collected from various depths in the VFS showed a minimal buildup of nutrients in the top soil profile but indicated a gradual buildup of nutrients at the depth of the subsurface drain. Results demonstrate that although a VFS can be very effective in reducing runoff and nutrients from surface flow, the presence of a subsurface drain underneath the VFS may not be environmentally beneficial. Such a combination may increase NO 3-N transport from the VFS, thus invalidating the purpose of the BMP.

Evaluating the Bray P1 Test on Alkaline, Calcareous Soils

Soil test phosphorus (STP) measurements are important for predicting crop P needs and for P loss risk assessments. Previous work indicates that the Bray P1 method extracts less P and does not correlate as well with Mehlich 3 or Olsen STP methods in alkaline or highly calcareous soils. This research was conducted to determine if the Bray P1 test is an appropriate method for the eastern red soil (ERS) region of Wisconsin, where pH typically ranges from 7 to 8 and soils are often calcareous. Soil samples (n = 113) from the ERS region and comparison soils (CS) from Iowa and Kansas (n = 38) with high pH and carbonate content were analyzed for P using the Bray P1, Mehlich 3, and Olsen methods and for soil pH and carbonate content. Results indicate that Bray P1 is strongly correlated with Olsen and Mehlich 3 for all samples in ERS regardless of carbonate content (R2 = 0.83 and 0.98, respectively), but only weakly correlated to Olsen and Mehlich 3 for Iowa and Kansas soils with carbonate contents ≥ 5 g kg−1 (R2 = 0.01 and 0.08, respectively). Further investigation indicated that carbonate in CS is calcitic while in ERS it is dolomitic. Because dolomite reacts much more slowly than calcite, Bray P1 is not neutralized in ERS during the 5 min extraction time. For soil with unknown carbonate content, a pH measurement on the Bray P1 filtrate can identify samples where Bray P1 is neutralized and an alternative P extractant should be used.

Potato Yield and Tuber Set as Affected by Phosphorus Fertilization

A 3 year field study on a loamy sand soil with medium to high soil test phosphorus (P) concentrations (25 to 33 mg kg−1 Bray P1) was conducted to evaluate the effect of P fertilizer rate, source, and timing, and starter nitrogen (N) rate on potato (Solanum tuberosum L. cv. Russet Burbank) yield, tuber size, tuber set, petiole P concentration, and P uptake and distribution within the plant. Nine fertilizer treatments compared banded P rates of 0, 37, 42, and 74 kg P ha−1, the P sources monoammonium phosphate (MAP) and diammonium phosphate (DAP), P banded at planting vs. split applications at planting and emergence, and starter N rates of 38 and 66 kg N ha−1. Phosphorus fertilizer application increased total tuber yield and yield of undersized tubers (tubers less than 85 g), but decreased the proportion of large-sized tubers (greater than 285 g). Due to the increases in small, unmarketable tubers, P fertilizer application did not have a significant effect on marketable tuber yield (tubers greater than 85 g). The total number of tubers per plant and the number of undersized tubers were also higher, and the number of large tubers was lower, when P was applied compared with the zero P control. Both the number and yield of undersized tubers increased as P application rate increased. Petiole P concentrations were generally consistent with the rate of P applied, but they varied by year in magnitude and their pattern through the season. Petiole P was positively correlated with the number of tubers per plant, but only correlated for 1 year with differences in total yield. Phosphorus application increased total P uptake due primarily to an increase in tuber P concentration. Increases in total uptake and tuber P increased as P application rate increased, but differences in uptake were small relative to the amounts of P applied. Phosphorus source and timing and starter N rate did not consistently affect tuber yield, number, or size, petiole or tuber P concentration, and P uptake. The results of this study indicate that P nutrition can play an important role in regulating tuber set.