David H. Hardy

Leaching of Nutrients and Trace Elements from Stockpiled Turkey Litter into Soil

In addition to nutrients, poultry are fed trace elements (e.g., As) for therapeutic purposes. Although a large proportion of the nutrients are assimilated by the birds, nearly all of the As is excreted. Hence, turkey litter constituents can leach into the soil and contaminate shallow ground water when it is stockpiled uncovered on bare soil. This study quantified the leaching of turkey litter constituents from uncovered stockpiles into the underlying soil. Four stockpiles were placed on Orangeburg loamy sand in summer 2004 for 162 d; 14 d after their removal, four stockpiles were created over the same footprints and left over winter for 162 d. Soil samples at depths of 7.6 to 30.5 cm and 30.5 to 61 cm adjacent to and beneath the stockpiles were compared for pH, electrical conductivity, total C, dissolved organic C, N species, P, water-extractable (WE)-P, As, WE-As, Cu, Mn, and Zn. All WE constituents affected the 7.6- to 30.5-cm layer, and some leached deeper; for example, NH(4)(+)-N concentrations were 184 and 62 times higher in the shallow and deep layers, respectively. During winter stockpiling, WE-As concentrations beneath the stockpiles tripled and doubled in the 7.6- to 30.5-cm and 30.5- to 61-cm layers, respectively, with WE-As being primarily as As(V). Heavy dissolved organic C and WE-P leaching likely increased solubilization of soil As, although WE-As concentrations were low due to the Al-rich soil and low-As litter. When used as drinking water, shallow ground water should be monitored on farms with a history of litter stockpiling on bare soil; high litter As; and high soil As, Fe, and Mn concentrations.

Evaluation of an Organic Copolymer Fertilizer Additive on Phosphorus Starter Fertilizer Response by Corn

Fertilizer additive products have recently been developed with the intention of reducing phosphate fixation and improving phosphorus plant availability. We conducted two experiments at multiple North Carolina locations from 2007-2009 to evaluate the effects of an organic copolymer phosphorus fertilizer additive, AVAIL Phosphorus Fertilizer Enhancer (Specialty Fertilizer Products, Leawood, KS), on corn (Zea maize L.) nutrient uptake, growth, and yield. Treatments included a combination of diammonium phosphate (DAP, [(NH ) HPO ]) P fertilizer rates with and without AVAIL. Grain yields did not differ across fertilizer treatments or across low, medium, or very high initial soil test phosphorus. Grain P concentration differed among treatments in only 2 of 16 site-years, where the N-only treatment had less tissue P than the treatments including P with or without AVAIL. Also, Nonly plots occasionally had shorter plants compared with DAP and DAP + AVAIL. Treating DAP with AVAIL did not consistently affect corn plant growth parameters in the Piedmont and Mountain Regions of North Carolina, and using treated DAP did not offer a consistent agronomic benefit over DAPor N-only fertilization. Introduction New synthetic organic copolymer phosphorus fertilizer additives have been recently developed to combat P-limited crop productivity by reducing phosphate fixation in soil. These products do not supply nutrients and cannot be evaluated based on nutrient content. Some manufacturers claim that these products enhance cation exchange capacity (CEC), moisture-holding capacity, and soil organism populations, and may also stimulate plant root growth and development (4). However, Crozier et al. (4) report that only a small (0.01 to 0.12 meq/100 g) change in CEC could be expected under typical recommendation rates for many of these products and that an increase of CEC in the root zone or carry-over CEC changes for the subsequent crop is unlikely. Similarly, Jones et al. (8) reported that labeled humic acid rates may not significantly increase organic acid concentrations in the soil, based on their greenhouse wheat study where humic acid coatings on monoammonium phosphate (MAP) did not increase P solubility, availability, or uptake, nor did it increase spring wheat grain yields on Montana calcareous and noncalcareous soils. These two studies imply that in order to substantially increase CEC or soil humate, rates much greater than those recommended on product labeling may be needed. Currently, one organic copolymer phosphorus fertilizer additive being marketed throughout much of the USA is AVAIL Phosphorus Fertilizer Enhancer. The AVAIL product is available for use with either granular or liquid phosphate fertilizers and consists of long chained, high cation exchange capacity maleic-itaconic copolymers (17,18). In dry form, AVAIL is designed to be coated 4 4 4 22 March 2013 Crop Management onto granular phosphate fertilizers and is reported to surround P fertilizer in a water-soluble ‘shield’ that expands to block the elements that tie-up P in soil (e.g., Ca, Mg, Fe, and Al) (17,18). Research results from investigations on the effects of AVAIL have been quite variable. A one-year trial in Ohio did not find a corn yield difference among plots treated with or without AVAIL, though soil sampling indicated that additional P was not required to increase corn yield (11). Thus, starter P with or without AVAIL was not likely to increase yields in that field. McGrath and Binford (12) conducted a 3-year corn trial in the Delmarva area and found that none of their eight site-years showed an early plant growth or yield response on AVAIL treated plots. However, early plant growth was increased in all years and grain yield increased during two site-years when a P starter fertilizer was applied. Ward (19) investigated corn growth and yield response to AVAIL over eight site-years in Kansas during the 2008-2009 growing seasons. While all sites had initial Mehlich-3 extractable P (M3P) of ≤ 15 mg/kg, where a P response could be expected, only one of the eight site-years showed a significant yield response to P fertilizer addition, and there were no significant responses in V4 plant biomass, R1 ear leaf P concentration, grain yield, moisture, test weight, or grain P concentration as a result of the AVAIL-treated P fertilizer treatments. A 3-year corn trial in southern Minnesota on low and medium-high Olsenextractable P soil also found inconsistent yield results when comparing MAP and DAP with AVAIL-treated MAP and DAP; a yield response to broadcastapplied AVAIL-treated DAP over untreated DAP was observed in 1 of 2 years, and no response was seen with AVAIL-treated MAP compared with untreated MAP (15). In contrast, Gordon (7) reported increases in both corn grain and soybean (Glycine max L.) yields averaged over 3-years in north-central Kansas for AVAIL-treated MAP compared with untreated MAP on a soil with a 22 ppm of Bray-1 P. Therefore, the objective of our study was to evaluate corn plant growth and grain yield response to starter P fertilizers applied with and without AVAIL on sites ranging in initial soil test P (STP). Field Studies Study 1. Research was conducted in 2007 and 2008 at seven sites on three research stations in North Carolina: Piedmont Research Station, Salisbury (Salisbury A, B, and C); Mountain Research Station, Waynesville (Waynesville A and B); and Mountain Horticultural Crops Research Station (MHCRS), Mills River (Mills River A and B), and at one cooperating farmer site in Buncombe County (Buncombe), representing 14 site-years. Corn was grown on low (13-30 mg P/kg), medium (31-60 mg P/kg), high (61-120 mg P/kg), and very high (>120 mg P/kg) STP and varying soil textures (Table 1). A representative 0-20 cm soil sample from each plot was analyzed using Mehlich-3 extractant to determine STP before treatment. Treatments were arranged in a randomized complete block design (RCBD) with four replications and included DAP (18-460) at 15 kg P/ha and 13 kg N/ha, DAP plus AVAIL (treated by supplier) at 15 kg P/ha and 13 kg N/ha, or ammonium nitrate (AN [NH4NO3]) only at 224 kg N/ha at planting. Both years, starter P fertilizer was surface applied in a 10-cm band over the row at planting. All DAP and DAP + AVAIL plots received an additional 211 kg N/ha as AN surface-broadcast at planting, while the N-only plots received AN surface-broadcast at planting. Corn was planted in no-till plots 7.6-m long by 3.7-m wide (4 rows, 0.91-m row spacing) at Salisbury and Buncombe. The sites at Mills River and Waynesville were 9.1-m long by 3.7-m wide (4 rows, 0.91-m row spacing) and were managed with conventional tillage (fall moldboard plow followed by two disk passes in subsequent spring). 22 March 2013 Crop Management Table 1. Site locations, year, soil series, and pre-study soil chemical characteristics (0-20 cm) for each of the 16 site-years. Corn plant height has often been used as an indicator of early season growth, corn total biomass, and grain yield (1,6) Thus, average plant height in each plot was measured 3 weeks after emergence; corn plants were measured from the ground to the top of the whorl. Tassel percentage was measured 8 to 10 weeks after planting. Corn grain yield was determined by hand-harvesting and weighing ears from the center 3.05 m of the center two rows of each plot and grain moisture was measured with a grain moisture meter. Grain samples were dried at 40°C for 48 h then ground and analyzed for N and P concentration using a Perkin-Elmer CHN Elemental Analyzer (Model II), and Pregl and Dumas analysis (5). The 2007-2008 growing season rainfall was less than 30-year average growing-season rainfall at each location. The growing seasons both years were exceptionally dry, as the entire state of North Carolina experienced drought conditions throughout that time (13) (Table 2). The average monthly temperatures during the 2007 and 2008 seasons at Mills River, Buncombe, and Waynesville were warmer than average, except in July at Waynesville when temperatures were cooler (Table 2). Salisbury temperatures were cooler than average except for July which was warmer. Analysis of variance for yield, N and P accumulation, plant height, and tassel percentage was performed using SAS PROC MIXED (16). Data were analyzed by location with treatment and rates as fixed effects. Tests of fixed effects were computed using ddmf = kl option of the MODEL statement. Differences in measured variables due to treatments were considered significant at P ≤ 0.05. Location Year Region Soil series HM (g/kg) pH P K (mg/kg) Mills River A 2007 Mountain Hayesville loam 7.6 6.0 72 199 2008 7.1 6.3 136 188 Mills River B 2007 Mountain Statler fine sandy loam 5.8 5.9 194 198 2008 4.6 5.8 121 148 Salisbury A 2008 Piedmont Hiwassee clay 3.0 5.6 57 145 Salisbury B 2007 Piedmont Chewaclo loam 3.8 5.5 110 77 2008 3.5 6.4 166 93 Salisbury C 2007 Piedmont Mecklenburg loam 5.5 6.9 385 409 2008 2.7 7.2 387 327 Waynesville A 2007 Mountain Cullowhee-Nikwasi complex 12.6 5.7 136 133 2008 11.7 5.5 141 110 Waynesville B 2007 Mountain Braddock clay loam 30.0 6.1 174 437 2008 27.0 6.2 159 385 Buncombe 2008 Mountain French loam 6.5 6.1 14 41 MHCRS 2008 Mountain Dillard loam 24.0 6.3 45 159 2009 Comus fine sandy loam 32.8 5.4 29 117 22 March 2013 Crop Management Table 2. Precipitation and temperature data for the 16 site-years, recorded by the State Climate Office of North Carolina. * Source: State Climate Office of North Carolina (www.nc-climate.ncsu.edu). Study 2. Research was conducted in 2008 and 2009 at the MHCRS. Soil test P was determined before planting using procedures as described for Study 1 (Table 1). Corn was grown on low and medium STP soils using conventional tillage (fall moldboard plow followed by spring disking). Average initial STP at Mills River was 35 mg/kg, and ranged from 16.2 to 58.4 mg/kg during the 2 years and plots (data not shown). Eighty-six percent of the plots tes

Response of Virginia market type peanut to interactions of cultivar, calcium, and potassium.

Peanut kernel size can influence response to calcium. While runner market type peanut cultivars often do not require supplemental calcium at flowering, application of gypsum (CaSO ) is routinely recommended for large-seeded Virginia market type peanut cultivars. However, kernel size varies considerably for Virginia market type peanut. Research was conducted from 2001-2005 at two locations in North Carolina to determine if the gypsum rate with or without prior potassium application should vary for the Virginia market type peanut cultivars NC-V 11 (625 kernels/lb seed) and Gregory (450 kernels/lb seed). Although the percentage of total sound mature kernels (%TSMK) was not affected by the interaction of cultivar and gypsum rate, pod yield and the percentage of extra large kernels (% ELK) was affected by this interaction. The interaction of location, year, and gypsum rate was significant for pod yield, %TSMK, and %ELK. Potassium had no major effect on pod yield or market grade characteristics. Seed germination and percentages of calcium deficient kernels were not affected by the interaction of cultivar and gypsum rate but was affected by the main effect of these treatment factors. These data suggest that although differences in peanut response to Virginia market type peanut exist, increasing the rate of gypsum above the rate currently recommended is not necessary for large-seeded Virginia market type peanut. Introduction The need for adequate calcium in the pegging zone of soil for kernel development is well documented for peanut (2,3,7,8,9,19). A strong relationship between pod yield and soil calcium concentration exists for small-seeded runner market type peanut, but the relationship is relatively poor for large-seeded Virginia market type peanut (7,8). Cooperative Extension recommendations in several states in the United States include soil testing as a tool for determining the need for supplemental gypsum application at flowering for runner market type cultivars (1,6,10,11,13). Because of the poor relationship between soil calcium concentration and pod yield for Virginia market type peanut, supplemental calcium is generally recommended for all large-seeded Virginia market types (1,6,10,11,13). However, Virginia market type peanut vary considerably in size of kernels and pods, and in recent years some growers have applied rates of gypsum higher than the standard recommendation for largeseeded cultivars (13). Research is needed to determine if gypsum rates need to be adjusted for Virginia market type peanut based on kernel and pod size. The concentration of potassium in soil can influence calcium absorption by developing kernels and pods (7,8), and recommendations on gypsum application to runner market types include determining the ratio of calcium to potassium in the pegging zone (11,13). Elevated concentrations of potassium in the pegging zone could interact with gypsum rate and cultivar kernel size. In a 4 26 February 2010 Crop Management survey of growers in North Carolina with Virginia market type peanut with pod yields typically higher the state average, approximately 80% of growers applied some form of N-P O -K O in the spring prior to planting (17). In this same group of growers, 98% applied gypsum at flowering (17). The relationship of calcium and potassium fertility has not been evaluated with more recently released Virginia market type peanut cultivars with varying kernel size. The cultivars Gregory and NC-V 11 offer the widest range of kernel and pod size of Virginia market type peanut grown commercially (13). These cultivars have similar disease reaction, and pod maturity of these cultivars progresses in a similar manner (13,20). Research was conducted to define interactions among the cultivars Gregory and NC-V 11, gypsum rate, and potassium to determine if the gypsum rate needs to be modified based on kernel and pod size of Virginia market type peanut. Locations, Soil Series, Tillage, and Pest Management The experiment was conducted in North Carolina from 2001-2005 at the Peanut Belt Research Station located near Lewiston-Woodville and the Upper Coastal Plain Research Station located near Rocky Mount. Soil at LewistonWoodville was a Norfolk sandy loam (fine-loamy, siliceous, thermic, Typic Paleudults). Soil at Rocky Mount was a Goldsboro loamy sand (fine-loamy, siliceous, thermic Aquic Paleudults). Peanut was planted in conventionallyprepared raised seedbeds in plots 2 rows wide (36-inch spacing) by 30 ft in length. Production and pest management practices were based on Cooperative Extension recommendations for the region (5,13,14,20). Cultivar, Gypsum, and Potassium Treatments Treatments consisted of a factorial arrangement of two levels of cultivar (Gregory and NC-V 11), three levels of gypsum (no gypsum, the recommended use rate of gypsum, and 1.5 times the recommended use rate of gypsum), and two levels of potassium fertilizer applied immediately after planting to the soil surface [no potassium and 250 lbs/acre 0-0-60 (N, P O -K O)]. The seeding rate for Gregory (12) (450 seeds/lb) was 150 lbs/acre (13). The seeding rate for NC-V 11 (22) (625 seeds/lb) was 115 lbs/acre (13). Cultivars were seeded at a rate designed to achieve an in-row plant population of 4 to 5 plants/ft. The broadcast standard rate of gypsum during 2001-2004 was 1250 lbs/acre (USG 500, 70% calcium sulfate) (13). Gypsum at 600 lb/acre (USG Ben Franklin, 85% calcium sulfate) (13) was banded in 2005 (18-inch band on rows spaced 36 inches apart). Rates are based on treated area. Gypsum was applied in late June of each year at early flower production. Immediately prior to application of gypsum, twelve soil cores to a depth of three inches were collected from no potassium and potassium-treated plots for the cultivar Gregory. Soil pH, soil potassium, and soil calcium levels for these samples are presented in Table 1. Peanut was dug and vines were inverted in late September or early October based on pod mesocarp color (21). Pods and vines were allowed to air-dry for 4 to 7 days prior to threshing, and final pod yield was adjusted to 8% moisture. Percentage of extra large kernels (%ELK) and total sound mature kernels (% TSMK) were determined from a one pound sample of pods collected at harvest. One hundred kernels from the sound mature kernel fraction of each sample during 2001, 2004, and 2005 were used to determine the percentage of kernels showing a calcium deficiency and standard germination (4). 2 5 2

Comments on the paper ‘Spatial and temporal variability in excessive soil phosphorus levels in eastern North Carolina’ by Cahoon and Ensign

The Agronomic Division of the North Carolina Department of Agriculture and Consumer Services would like to comment on the recent article: Cahoon, L.B. and Ensign, S.H. 2004. Spatial and temporal variability in excessive soil phosphorus levels in eastern North Carolina. Nutrient Cycling in Agroecosystems 69: 111–125. The authors based their article on Mehlich soil test data generated by our laboratory. We would like to clarify some erroneous information and provide insight regarding NCDA&CS soil test and fertilizer data. As a state government laboratory, our soil test data are accessible to public use and scrutiny. Valid interpretation of this information requires great familiarity with our soil test methods, N.C. soil properties, and local agriculture. Statements in Cahoon and Ensign’s article indicate that they did not have complete knowledge regarding (1) NCDA&CS Agronomic Division soil testing procedure for analyzing phosphorus during the period in question – 1980 through 2001, (2) NCDA&CS Agronomic Division soil sampling guidelines, (3) soil properties that affect retention of phosphorus, and (4) NCDA&CS Agricultural Statistics Division fertilizer tonnage report data.