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HighlightsCrop coefficients (Kcb) were calculated using Normalized Difference Vegetative Indices (NDVI) and compared to the FAO-56 method.Cotton yields using NDVI-Kcb based irrigation scheduling to a uniform checkbook irrigation were compared.Irrigated cotton yields were not significantly different between irrigation methods but were significantly higher in years requiring higher volumes of irrigation water.Cotton fiber quality was not significantly different for the two irrigation methods or plant populations.Abstract. Irrigation timing is crucial for achieving high cotton yields and lint quality. This irrigation timing is more challenging in the southeastern U.S. Coastal Plain region due to its spatial variable sandy soils with low water and nutrient holding capacities and rainfall variability during the growing season. To address these challenges, we conducted a 2-year (2017 and 2018) study evaluating two irrigation scheduling methods under a variable rate irrigation system. The two irrigation methods were: (1) a uniform irrigation management based on weekly crop water usage, and (2) spatial crop coefficients derived from normalized difference vegetative indices (NDVI). We compared cotton yields and water use efficiency using the two irrigation scheduling methods at two different planting densities. The two plant populations were 5 and 11.5 plants m2 to provide different NDVI readings and water requirements. In 2017, there were no significant differences in cotton yields due to the adequate rainfall during the growing season that required only three irrigations events. The mean irrigation depth for the NDVI method was significantly lower than the uniform method (56 and 64 mm, respectively, LSD = 4.2). In 2018, there was lower rainfall during the growing season requiring eight irrigation events and the cotton yields in the two irrigation treatments were significantly higher than the rainfed treatment. Irrigation depths in 2018 were not significantly different for the two irrigation methods. Water use efficiencies were not significantly different for the two irrigation methods. The planting density had little impact on the cotton yields, irrigation depth, water use efficiency, or cotton fiber quality. These results indicate that the NDVI-derived crop coefficient values were as effective in prescribing irrigation applications as the uniform irrigation method for irrigation management. The NDVI-derived crop coefficient irrigation method appears to be a useful tool for managing irrigation and developing irrigation prescriptions. Keywords: Cotton, Irrigation scheduling, Normalized difference vegetation indices, Variable rate irrigation

Novel biotechnology on transgenic plants capable of metabolizing phosphite (Phi), a reduced form of P, could improve the effectiveness of P fertilizers and reduce the P footprint in agriculture with the benefit of suppressing weed growth. However, potassium Phi (K-Phi) salts used as fertilizer are highly soluble in water. At the same time, sandy soils of the Southern Coastal Plain are vulnerable to leaching losses resulting from long-term Pi fertilizer application. We performed a replicated leaching trial using five soil materials that included three surface and two subsurface layers from cultivated topsoil (Ap horizon) with contrasting Phi and Pi sorption capacities. Each soil received three treatments K-Phi at rates 0 (control), 24, and 49 kg P ha−1 and leached twice with de-ionized water. All K-Phi-treated soils leached Phi except for the controls. A phosphorus saturation ratio (PSR) calculated from P, Al, and Fe in acid extracts indicated increasing environmental risk of Phi leaching in soils with lower Phi and Pi sorption capacities at rising rates of applied K-Phi. Because plants rapidly absorb Phi, further studies on the environmental impact of K-Phi fertilizer use should include the interaction of plants with soil properties and soil microbial activity at optimal Phi application rates for growing transgenic plants able to use Phi as a nutrient source.

The Chronicle of Muchimaro (Muchimaro den 武智麻呂伝) is the third and final extant part of the History of the Fujiwara House (Tōshi kaden 藤氏家伝), an eighth century history connected with, and partly attributed to, the courtier Fujiwara no Nakamaro (藤原仲麻呂; 706–764), Muchimaro’s son. For the translations of the first two parts, see Bauer 2017 and Bauer 2018. Attributed to Enkei, a monk who probably was close to Nakamaro, the text celebrates the virtues and achievements of Muchimaro, a courtier whose life was cut short during the smallpox epidemic of 737. This disaster heavily affected the Fujiwara family and court politics: the four main Fujiwara officials passed away in one year, along with about one-third of the entire population. Apart from Muchimaro, his three brothers also passed away during the epidemic: Fusasaki 藤原房前 (681–737); Umakai 藤原宇合 (694–737) and Maro 藤原麻呂 (695–737). One of the consequences of the epidemic was the sudden rise of Tachibana no Moroe after 737 and the subsequent competition between him and Muchimaro’s sons, mainly Nakamaro. The compilation of The History of the Fujiwara House can thus be seen as part of an attempt to reestablish the authority of the Fujiwara line by Nakamaro. The text presents Muchimaro as close to the sovereign and celebrates his virtues as an official by referring to and drawing from a variety of continental sources, a characteristic that can also be discerned in the first two parts of the History.

Site-specific variable-rate irrigation (VRI) systems can be used to spatially manage irrigation within sub-field-sized zones and optimize spatial water use efficiency. The goal of the research is to provide farmers and consultants a tool to evaluate the potential benefits of implementing VRI. The specific objective of this research is to evaluate the potential water savings using VRI management compared with uniform irrigation management to maintain soil water holding capacity above 50% depletion using two irrigation scenarios: 1) a standard 12.5 mm irrigation per application; and 2) an application to refill the soil profile to field capacity. A 21-year simulation study was carried out on a selected field with varying degrees of soil and topographic variability. The simulated field had 12 soil mapping units with water holding capacities in the top 0.30-m ranging from 42 to 70 mm. The 21-year simulation covering all weather conditions for each soil produced only two significantly different irrigation management zones for scenario 1, and for scenario 2 only one management zone. However, when the 21-year period was divided into periods with different ratios of rainfall to reference evapotranspiration, the simulations identified 1 to 5 management zones with significantly different irrigation requirements. These results indicate that variable rate irrigation system design and management should not be solely based on long term average weather conditions. Years with differing weather conditions should be used for potentially identifying management zones for VRI systems. Irrigation application depths between management zones ranged from 17 to 38 mm. However, when the actual soil areas of the study field were utilized to calculate the total volume of irrigation water applied, it resulted in an increase in water usage in the 2 and 4 management zones ranging from -1.2% to 5.8%. Water usage with VRI over uniform irrigation was greater by -1.6% to 6.8% in the 12.5 mm irrigations and by -1.2% to 2.2% for the field capacity irrigations Keywords: Management zones, Precision farming, Variable-rate irrigation, Water conservation.

A 4-yr study was conducted to determine the degree of aggregation of thrips and injury in cotton, Gossypium hirsutum L., and their spatial association with a multispectral vegetation index (normalized difference vegetation index [NDVI]) and soil apparent electrical conductivity (ECa). Using the Spatial Analysis by Distance IndicEs analyses (SADIE), adult thrips were significantly (P < 0.05) aggregated in 4 out of 24 analyses for adult thrips (17%), 4 out of 24 analyses for immature thrips (17%), and 2 out of 15 analyses for injury (13%). The SADIE association tool showed that NDVI values were associated with adult thrips in 2 out of 20 paired datasets (10%), with immature thrips in 3 out of 20 paired datasets (15%), and with thrips injury in 1 out of 14 paired datasets (7.1%). Soil ECa values were generally more associated with thrips variables than NDVI, with shallow ECa positively associated with adult thrips in 6 out of 21 paired datasets (28.6%), with immature thrips in 8 out of 21 paired datasets (40.0%), and with thrips injury in 8 out of 14 paired datasets (57.1%). The greater frequency of positive associations between thrips variables and soil ECa suggests a greater potential for site-specific management, particularly in the Coastal Plain of the southeastern United States, where soil types are highly variable.

Grain sorghum is one of the top five cereal crops and an important grain crop throughout the world. It is generally considered more drought tolerant compared to other grain crops such as maize. Recently, in the U.S. eastern Coastal Plain region, there was an emphasis on increasing regional grain production in which grain sorghum played an important role. The region’s soils have low water holding capacities that combined with high rainfall variability cause crops frequently to be exposed to water stress. In this research, an experiment was conducted to evaluate the yield response of two grain sorghum varieties at different supplemental irrigation depths and three nitrogen levels. During our 3-year study, seasonal rainfall was adequate to produce acceptable grain sorghum yields. Seasonal rainfall ranged from 421, 365, and 357 mm in 2012, 2013, and 2014, respectively. These rainfall amounts were greater than the seasonal calculated crop evapotranspiration requirement, but rainfall distribution was not adequate to maintain acceptable soil water potentials throughout the growing season. Supplemental irrigation was 51, 38, and 13 mm in 2012, 2013, and 2014, respectively, to maintain soil water potential above -30 kPa. These irrigation amounts did not increase grain sorghum yields. No significant differences were found in grain yield between the two sorghum varieties or for increasing nitrogen applications. This lack of response to nitrogen applications may have been related to adequate supplies in the soil from previous crops. Results from this study suggest that there would be little benefit for supplemental irrigation for sorghum production in the U.S. eastern Coastal Plain. Keywords: Keyword. Grain sorghum, Irrigation, Irrigation management.

Controlling for experimental error attributable to field heterogeneity is important in high-throughput phenotyping studies that enable large numbers of genotypes to be evaluated across time and space. In the current study, we compared the efficacy of different experimental designs and spatial models in the analysis of canopy spectral reflectance data collected on upland cotton (Gossypium hirsutum L.). Canopy spectral reflectance, as measured by normalized difference vegetation index (NDVI), was measured at first bloom on three upland cotton performance trials conducted in Florence, SC, during 2014 and 2015. The relative efficiency and estimates of genotype effects were compared among randomized complete block, an α-lattice incomplete block, row–column incomplete block, nearest neighbor adjusted, and spatially correlated error models. The row–column model provided the greatest improvement in the precision of genotype effect estimates compared with the randomized complete block model. Genotype rankings based on NDVI varied substantially between the randomized complete block and alternative models, particularly at 5 and 10% selection intensities. These results suggest that the use of more complex experimental designs and spatial analyses should be routinely considered to minimize experimental error due to field heterogeneity and improve the precision and reliability of traits measured using high-throughput phenotyping systems. These findings also indicate that further research into the effects of field heterogeneity on the relationship between NDVI and lint yield in upland cotton is warranted.

A 3-year (2013–2015) field study was conducted to evaluate the effect of integrated nutrient management (NM) and three irrigation scheduling methods (IS): irrigator pro (IPro); normalized difference vegetative index (NDVI) and soil water potentials (SWP) on phosphorus (P) dynamics and phosphatase activity in four Coastal Plains soil types (ST) at various growth stages (CS: V6, six leaves; V16, sixteen leaves; and R1, silking) of corn (Zea mays L.). Nitrogen fertilizer was applied at two rates: 157 and 224 kg ha−1 through the irrigation system in three applications. Phosphorus dynamics and phosphatase activity varied significantly (p ≤ 0.0001) with year (Y), CS and ST, but not with NM. Phosphorus uptake of corn had an increase of about 1200% from V6 to R1. Both the Mehlich extractable P and water soluble P showed declining trends from V6 to R1. Concentration of P in pore water differed significantly (p ≤ 0.05) with IS in 2014 and 2015, but not in 2013. The order of the concentrations of P in pore water (averaged across ST) as affected by IS is as follows: 2013 (IPro = NDVI = SWP); 2014 (SWP = IPro < NDVI); and 2015 (IPro < NDVI < SWP). Concentration of phosphatase among the different ST was affected by CS, from V6 to R1 and soil depth, but not with NM. The difference in phosphatase concentration between the upper and lower soil horizons (averaged across Y and ST) was about 67.7 μg g−1 h−1. Our results have significant implication on P mobility, availability and management in areas where inputs of P in fertilizers may have had exceeded P output in harvested crops. Our results further suggest that understanding of P inputs and outputs which include P accumulation in soils and plants, as well as P losses is critical to determining the environmental balance and accountability of P in agricultural ecosystem. It is imperative to have a holistic understanding of P dynamics from soil to plant by optimizing P management and improving P-use efficiency.

Agriculture is one of the largest sources of nutrient contamination, mainly inorganic nitrogen (N) fertilization of intensive crops, such as maize (Zea mays L). Proper irrigation management can reduce nutrient leaching while maintaining crop yield, which is critical in enhancing the sustainability of agricultural crops on soils with low water and nutrient holding capacities. A three-year (2012–2014) field study was conducted to evaluate the effects of three irrigation scheduling methods (ISM): Irrigator Pro (IPRO); Normalized Difference Vegetative Index (NDVI); and Soil Water Potentials (SWP) and two rates of N applications (NM) on pore water nitrate and phosphate in four soil types (ST) with maize production in Coastal Plain Region, USA. Soil pore water nitrate varied significantly with ISM and NM, but not with ST. The IPRO method had the lowest soil water pore nitrate followed by SWP and NDVI. The low N application rate resulted in lower nitrate concentration (13.4 mg L−1) than the high N rate (17.0 mg L−1). Soil water pore phosphate was not affected by ISM, NM and ST. The use of IPRO reduced the concentration of pore water nitrate by about 39% and 33% when compared with NDVI and SWP, respectively. Using IPRO method resulted in lower soil water pore nitrate and phosphate concentrations, results indicate scheduling method may be a way to reduce nutrient losses. Results of our study suggest that irrigation management decision may affect nitrogen and phosphorus availability for achieving optimum yield of maize while potentially minimizing nutrient losses via leaching.

Biochars made from animal manure feedstock appear to be a potential phosphorus (P) fertilizer source. Five different manure-derived biochars, pyrolyzed at two different temperatures (350 and 700 °C) were assessed for their potential as a P fertilizer for cotton (Gossypium hirsutum L.). A greenhouse study was conducted using a Uchee sand soil. Biochar was applied at rates that provided 40 mg P kg-1 soil. Four rates of calcium phosphate (0, 20, 40, and 60 mg P kg-1 soil) were included in the study. Cotton plants were allowed to grow to 60 days post-emergence at which point leaves and stems were harvested for physical and chemical analysis. The experiment was conducted twice. Results demonstrated that biochar worked as a P fertilizer and that feedstock choice combined with biochar processing temperature accounted for a majority of the differences among the 10 treatments tested. When applied at standard P fertilization rates, manure-derived biochars perform equally to calcium phosphate fertilizer.

Soil compaction management in the southeastern USA typically relies heavily on the practice of annual deep tillage. Strip tillage systems have shown considerable promise for reducing energy and labor requirements, equipment costs, soil erosion, and cotton plant damage from blowing sand. Replicated field trials were conducted for three years in South Carolina, to compare the performance of three different strip tillage systems to conventional tillage and no-till methods. A second objective was to investigate whether the frequency of deep tillage can be reduced by planting cotton directly using controlled wheel traffic into the previous year’s subsoiler furrow. Tillage treatments included: conventional tillage (disk-subsoil-bed), straight shank strip-till, bent-leg shank strip-till (Paratill), bent-leg shank strip till (Terra Max), and no-till. Deep tillage was performed in all plots the first year. In years two and three, the plots were split and half received annual deep tillage and the other half were not deep tilled either year. Tillage methods were compared side by side with and without irrigation. Deep tillage reduced soil compaction and increased taproot length and cotton yields than the no-till system. There was no difference in cotton lint yield between the strip-till systems and conventional tillage in either dry land or irrigated plots. Deep tillage increased cotton lint yields compared to no-till. There was no difference in lint yield between plots which were deep-tilled in all three years with those which had tillage operation only in first year of the test. Dry matter partitioning at first bloom was reduced in plant height, total dry weight, and leaf area in strip-till and no-till production systems compared to the conventional tillage system. The results suggest that all three strip tillage systems are equally effective for cotton production and that annual deep tillage is not necessary if controlled traffic is employed.

Ash from power plants that incinerate poultry litter has fertilizer value, but research is lacking on optimal land application methodologies. Experiments were conducted to evaluate calcitic lime and flue gas desulfurization gypsum (FGDG) as potential fillers for poultry litter ash land applications. The ash had phosphorus (P) and potassium (K) contents of 68 and 59 g kg&minus, 1, respectively. Soil extractable P and K were measured in an incubation pot study, comparing calcitic lime to FGDG at filler/ash ratios of 1:3, 1:2, 1:1, 2:1, and 3:1. After one month, soils were sampled and annual ryegrass (Lolium multiflorum Lam.) seeds were planted to investigate how plant growth and uptake of P and K were influenced by the fillers. Application of ash alone or with fillers increased soil extractable P and K levels above unamended controls by 100% and 70%, respectively. Filler materials did not affect biomass or P and K concentration of the ryegrass. A field study with a commercial spinner disc fertilizer applicator was conducted to compare application uniformity of ash alone and filler/ash blends. Overall, test data suggested that uniform distribution of ash alone or with fillers is feasible in field applications using a commercial fertilizer spreader.

Variable-rate irrigation (VRI) systems are irrigation systems that are capable of applying different water depths both in the direction of travel and along the length of the irrigation system. However, when compared to traditional irrigation systems, VRI systems require a higher level of management. In this research, our objective was to evaluate and compare three irrigation management methods for their potential in managing VRI systems. The three irrigation management methods were the Irrigator Pro for Corn expert system, measured soil water potential (SWP), and remotely sensed crop vegetative indices (NDVI) to estimate crop coefficients. These irrigation treatments were implemented over six soil types under a VRI system for three years. Corn yields differed among years; average yields were 15.6 Mg ha -1 in 2012, 10.5 Mg ha -1 in 2013, and 13.5 Mg ha -1 in 2014. However, corn yields for the three irrigation treatments were not significantly different for any one year. The mean yearly irrigation applied in 2012, 2013, and 2014 was 57, 7, and 156 mm, respectively. The mean water use efficiency (WUE) over the three years was significantly different, with values of 29.8, 16.8, and 23.8 kg grain ha -1 mm -1 for 2012, 2013, and 2014, respectively. For each individual year, the WUE among irrigation treatments was not significantly different. For the six soils types, there were no significant differences for corn yield or WUE. The Irrigator Pro for Corn and NDVI treatments managed irrigations as well as the traditional SWP-based treatment under the VRI system from 2012 to 2014. Each of these irrigation treatments was able to adequately manage irrigation spatially and produce adequate crop yields for the region. Each of these irrigation management treatments could be used effectively to manage irrigations under a VRI system with different management zones.

Intensive tillage, low-residue crops, and a warm, humid climate have contributed to soil organic carbon (SOC) loss in the southeastern Coastal Plains region. Conservation (CnT) tillage and winter cover cropping are current management practices to rebuild SOC; however, there is sparse long-term field data showing how these management practices perform under variable climate conditions. The objectives of this study were to use CQESTR, a process-based C model, to simulate SOC in the top 15 cm of a loamy sand soil (fine-loamy, kaolinitic, thermic Typic Kandiudult) under conventional (CvT) or CnT tillage to elucidate the impact of projected climate change and crop yields on SOC relative to management and recommend the best agriculture management to increase SOC. Conservation tillage was predicted to increase SOC by 0.10 to 0.64 Mg C ha for six of eight crop rotations compared with CvT by 2033. The addition of a winter crop [rye ( L.) or winter wheat ( L.)] to a corn ( L.)-cotton ( L.) or corn-soybean [ (L.) Merr.] rotation increased SOC by 1.47 to 2.55 Mg C ha. A continued increase in crop yields following historical trends could increase SOC by 0.28 Mg C ha, whereas climate change is unlikely to have a significant impact on SOC except in the corn-cotton or corn-soybean rotations where SOC decreased up to 0.15 Mg C ha by 2033. The adoption of CnT and cover crop management with high-residue-producing corn will likely increase SOC accretion in loamy sand soils. Simulation results indicate that soil C saturation may be reached in high-residue rotations, and increasing SOC deeper in the soil profile will be required for long-term SOC accretion beyond 2030.

During the Nara period (710–794), the Japanese religious and political landscape saw tremendous change. A new capital was built, Chinese legal codes were implemented, and the Buddhist temples grew in size and number. Traditionally, Nara period Buddhism has been described in terms of the so-called “Six Schools.” It is certainly the case that the 8th century became the cornerstone of later doctrinal and ritual developments, but the Buddhist context was more complex and intertwined than these six forms of Buddhism.

Flax (Linum usitatissimum L.) is a potential winter crop for the Southeast USA that can be grown for both seed and fiber. The objective of this research was to evaluate the effect of irrigation on flax straw, fiber, and seed yield of fiber-type and seed-type cultivars at different flax growth stages. The study was conducted during the winter growing seasons of 2010/2011, 2011/2012, and 2012/2013 near Florence, SC. Four fiber-type cultivars and one seed-type cultivar were grown with and without irrigation for two years. The four fiber-types were evaluated for straw and fiber yield in the third year. Soil water was monitored to trigger irrigations. Irrigation was applied before all four harvests in 2010/2011, before only the last harvest in 2011/2012, and was not applied in 2012/2013. Straw harvests were made at the onset of flowering, 10 days past the onset of flowering, 20 days past the onset of flowering, and when seeds were mature. Seed harvests were made at the end of the 2011/2012 and 2012/2013 growing seasons. In 2010/2011, plots had to be replanted in February so crop development was delayed. Irrigation increased straw yield at the last three harvests in that year. In the other two years, when planting occurred at normal times in the fall, irrigation did not influence straw or fiber yield. Irrigation had no significant effect on seed yield. The fiber-type cultivars did not differ for straw or fiber yield. At the onset of flowering harvest, the seed-type cultivar had similar fiber content to the fiber-type cultivars. The fiber-type cultivars had higher fiber content in later harvests. The results support previous research in that fiber-type cultivars appear viable for production as fiber winter crops in the region. The results also suggest that high straw yielding seed-type cultivars could be used, especially in systems with early straw harvests.

A better understanding of how bermudagrass (Cynodon spp.) regrowth is influenced by production inputs will aid in advancing precision management. The objectives were to evaluate the effect of irrigation and nitrogen (N) on normalized difference vegetative index (NDVI) during regrowth and evaluate the relationship between NDVI during regrowth to forage yield. Normalized difference vegetative index (NDVI) data were collected in an experiment evaluating two harvest schedules (four or eight week), four rates of irrigation (0, 4.2, 8.4, or 12.5 mm of water each irrigation event), and three rates of N (season total of 168, 336, and 504 kg N ha -1 ). Both irrigation and N influenced NDVI of bermudagrass during the regrowth periods of both the four- and eight-week harvest schedules, but there were no irrigation by N interactions. As was expected, regrowth (as measured by NDVI) in response to irrigation was dependent on the timing and duration of rain-free periods within the regrowth periods. Generally, NDVI increased with increasing N rate at most sampling dates. Regression slopes of yield versus NDVI measured near the end of the regrowth period were higher for the eight-week harvest schedule than for the four-week schedule. Within each harvest schedule, however; slopes were similar. The high correlation coefficients between NDVI late in the regrowth period and yield suggest NDVI is a useful tool for managing bermudagrass harvests.

Variable-rate irrigation (VRI) systems have the potential to conserve water by spatially allocating limited water resources. However, when compared to traditional irrigation systems, VRI systems require a higher level of management. In this 3-year study, we evaluated spatial irrigation management of a peanut crop grown under a VRI system using an expert system (Irrigator Pro). The irrigation management treatments evaluated were: (1) using Irrigator Pro (IP) to manage irrigation uniformly in plots with varying soils; (2) using Irrigator Pro to manage irrigation in plots based on the individual soils (IPS); (3) a treatment based on maintaining soil water potential (SWP) above −30 kPa (approximately 50 % depletion of available water) in the surface 30 cm of each soil within a plot; and (4) a non-irrigated treatment. Over the 3-year study, all irrigated treatments had significantly higher yields (4,230, 4,130, and 4,394 kg ha−1 for the IP, IPS, and SWP treatments, respectively) than the non-irrigated treatment (3,285 kg ha−1), yet the yields of the three irrigation treatments were not significantly different. Averaged over the 3-year experiment, the three treatments did not differ significantly in water usage. In the 2007 and 2009 growing seasons with below normal rainfall, the IP and IPS treatments required significantly greater total water than the SWP treatment. Overall, water use efficiency was significantly higher for the non-irrigated and SWP treatments (9.4 and 8.9 kg ha−1 per mm, respectively). The lower water use efficiency for the IP and IPS irrigation treatments (7.8 kg ha−1 per mm) was attributed to greater water applications mainly due to earlier growing season initiation of irrigation applications. However, the IP and IPS treatments maintained soil water potentials at the 30- and 60-cm depths at higher levels throughout most of the season. The two Irrigator Pro expert system treatments functioned as well as the SWP-based treatment. The Irrigator Pro expert system can be effectively used for site-specific management where management zone soils do not greatly differ. Further refinement of the expert system may be needed to improve its application in spatial irrigation applications.

Biochars made from livestock manures need to be better understood in relation to their high nutrient contents. Accordingly, the objective of this investigation was to assess the plant availability and agronomic efficacy of phosphorus (P) contained within chemical fertilization compared to the P contained in ten precisely prepared and characterized manure-derived biochars. Two identical greenhouse experiments were conducted using ryegrass (Lolium multiflorum Lam.). The ten biochars were created from dairy, swine, beef, turkey, and chicken manures. Each manure feedstock was converted into biochar at two temperatures (350°C and 700°C). The soil was a sand (Uchee series; loamy, kaolinitic, thermic Arenic Kanhapludults) with a low P content. The biochar-amended treatments received P on a basis of 50 mg P 2 O 5 kg -1 soil. The biochar treatments were compared to chemically fertilized treatments of 0 to 150 mg P kg -1 soil. The biochars did not contain yield-limiting levels of EC, pH, Zn, or Cu. Phosphorus in the manure-derived biochars was readily plant available. The biochars generally produced ryegrass yields similar to chemical fertilizer. The chicken 350°C biochar produced the highest ryegrass yield, and the swine 350°C biochar produced the lowest ryegrass yield. For the biochar treatments, the ryegrass Cu and Zn concentrations were within normal ranges, and they were not significantly different from the simple chemical fertilization treatments. Thus, for ryegrass growth, manure biochars can be used for their P-supplying capacities. This can be important to manure management, crop fertilization, and conservation of global P resources.

The Gloldnaya steppe has large areas of fertile sierozem soils that are important for crop production and its accompanying economic development. The soils are fertile loams, but because of the steppe's dry environment, they need to be irrigated. Our objective was to study irrigation management of cotton production on sierozem soils in southern Kazakhstan. From 2006 to 2008, we grew irrigated cotton on low, moderately, and highly saline sierozem soils in the South Kazakhstan Oblast. Soils were irrigated to reduce salinity and improve growth. Yields increased with reduced salinity especially because the highly saline soil could not support growth every year and because it had 33 to 40% less yield when cotton was grown on it. Soils were managed with multiple tillage and cultivations by machinery and hand, which maintained low bulk densities near the surface and a tillage pan at about the 30-cm depth. Future management improvements include fewer tillage operations, which would decrease energy needs and compac...

A 3-yr study was conducted to determine the degree of aggregation of stink bugs and boll injury in cotton, Gossypium hirsutum L., and their spatial association with a multispectral vegetation index (normalized difference vegetation index [NDVI]). Using the spatial analysis by distance indices analyses, stink bugs were less frequently aggregated (17% for adults and 4% for nymphs) than boll injury (36%). NDVI values were also significantly aggregated within fields in 19 of 48 analyses (40%), with the majority of significant indices occurring in July and August. Paired NDVI datasets from different sampling dates were frequently associated (86.5% for weekly intervals among datasets). Spatial distributions of both stink bugs and boll injury were less stable than for NDVI, with positive associations varying from 12.5 to 25% for adult stink bugs for weekly intervals, depending on species. Spatial distributions of boll injury from stink bug feeding were more stable than stink bugs, with 46% positive associations among paired datasets with weekly intervals. NDVI values were positively associated with boll injury from stink bug feeding in 11 out of 22 analyses, with no significant negative associations. This indicates that NDVI has potential as a component of site-specific management. Future work should continue to examine the value of remote sensing for insect management in cotton, with an aim to develop tools such as risk assessment maps that will help growers to reduce insecticide inputs.

In the southeastern region of the U.S., the cattle industry has a critical need for sustainable hay production. Yet this production is threatened by frequent short-term regional drought. This drought threat can be mitigated by properly managed irrigation. In this study on Tifton 85 bermudagrass, irrigation management, nitrogen fertility levels, and harvest interval were evaluated for their impact on hay quality and yield. The experimental treatments were arrayed in a split-plot design with harvest interval as the main treatment; irrigation by nitrogen (N) levels were the subplots. Treatments had four replicates and were repeated for two years. The optimal irrigation rate was set to maintain soil water potentials below -30 kPa. When needed, the full irrigation treatment received a 12.5 mm irrigation application. The reduced irrigation treatments received water at rates of 0%, 33%, and 66% of the full irrigation rate. In addition, each irrigation treatment had nitrogen rates of 168, 336, and 504 kg N ha-1. The irrigation and nitrogen treatments were harvested at four-week or eight-week intervals. Total harvests per year ranged from three to six. Over both years and for all harvests, there was no irrigation-nitrogen interaction for hay yield. Over all harvests, nitrogen significantly increased bermudagrass hay yield, nutrient concentrations, and forage quality. Forage quality was higher for the four-week harvest interval. Throughout the study, forage quality was maintained within desired industry standards. When irrigation was required, it significantly increased hay yield. During these periods, the four-week and eight-week 100% irrigation treatments yielded 612 and 1600 kg ha-1 greater, respectively, than the non-irrigated treatments. The four-week harvest interval was more sensitive to irrigation. Additionally, we observed a linear relationship between non-irrigated bermudagrass hay yields and average soil water potential. As soil water was depleted, non-irrigated hay yields decreased 31 kg ha-1 per kPa. Timely supplemental irrigation to maintain soil water potentials above -30 kPa can increase bermudagrass yields. Thus, irrigation management should be critically assessed for its potential role in sustaining hay production in the southeastern Coastal Plain.

Purpose The aim of the study was to evaluate the environmental fate of recovered manure phosphates for their effective use as crop fertilizers.

Sunn hemp (Crotolaria juncea), is a fast growing, high biomass yielding tropical legume that may be a possible southeastern bioenergy crop. When comparing this legume to a commonly grown summer legume e cowpeas (Vigna unguiculata), sunn hemp was superior in biomass yield (kg ha � 1 ) and subsequent energy yield (GJ ha � 1 ). In one year of the study after 12 weeks of growth, sunn hemp had 10.7 Mg ha � 1 of biomass with an energy content of 19.0 Mg ha � 1 . This resulted in an energy yield of 204 GJ ha � 1 . The energy content was 6% greater than that of cowpeas. Eventhough sunn hemp had a greater amount of ash, plant mineral concentrations were lower in some cases of minerals (K, Ca, Mg, S) known to reduce thermochemical conversion process efficiency. Pyrolytic degradation of both legumes revealed that sunn hemp began to degrade at higher temperatures as well as release greater amounts of volatile matter at a faster rate.

Longer rain-free periods are predicted to occur more often in the southeastern United States as a result of global climate change. This nonirrigated field study was conducted from 1997 through 2002, which coincided with the 1998-2002 drought that affected most of the United States. The objective was to determine the effect of rotation and tillage on cotton (Gossypium hirsutum L.) productivity. Treatments in the study were rotation [cotton rotated with corn (Zea mays L.), cotton planted after a rye (Secale cereale L.) winter cover crop, and continuous cotton with no cover crop] and tillage system (conventional tillage and conservation tillage). Two levels ofaldicarb [2-methyl-2-(methylthio)propanal O-{(methylamino)carbonyl}oxime] (0 and 1.18 kg a.i. ha -1 ) were also included because ofknown soil management effects on thrips (Frankliniella sp.) and root-knot nematodes (Meloidigyne incognita). The predominant soil types were Bonneau loamy sand (loamy, siliceous, subactive, thermic Arenic Paleudult) and Norfolk loamy sand (fine-loamy, kaolinitic, thermic Typic Kandiudult). Rotation did not affect cotton yield in any year. Tillage did not affect cotton yield in 1997. Conservation tillage resulted in an average 25% yield increase in cotton lint yield over conventional tillage during the 5-yr drought. Tillage and aldicarb affected both thrips and root-knot nematodes, but lack of interaction among these factors for lint yield suggested that management of these pests was not the predominant cause for the cotton yield increase with conservation tillage. Conservation tillage for cotton production could be an important method to help mitigate the effects of climate change in the region if change occurs as predicted.

Phosphorus can be recovered from broiler litter using a new process ("quick wash"). However, limited information is available on the beneficial use of this P product as plant fertilizer. The objective of this study was to determine the agronomic effectiveness of this P material. A greenhouse study was conducted with annual ryegrass (Lolium multiflorum Lam.) to compare the recovered phosphorus (RP) to both commercial triple superphosphate (TSP) and raw broiler litter (BL) as a P source. The study consisted of a 7-wk experiment that was repeated three times. Fertilizer rates were 0, 22, 44, 88, and 176 mg P kg -1 soil. Three harvests of the ryegrass were made at 2-wk intervals. On average, biomass production was higher than the control with no P for plants fertilized with RP, BL, or TSP. Total P uptake increased linearly with application rate for all three fertilizer materials. At the highest application rate, total P uptake was 36.1 mg pot -1 for TSP, 21.3 mg pot -1 for the BL, and 17.3 mg pot -1 for the RP. Chemical analysis of the RP material revealed that more than 90% of the total P in the RP material was mostly as citrate-soluble. Mehlich-3 extractable soil P at the end of the experiment indicated that less RP material dissolved than TSP during this short study. The RP material appears to have potential as a P fertilizer.

Long-term disk tillage (DT) for cotton (Gossypium hirsutum L.) production in the southeastern U.S. Coastal Plain has resulted in soil organic C (SOC) content reductions. Conservation tillage (CT) management in some studies can rebuild SOC levels. A field study, with two adjacent 3.5-ha fields, both containing soil series formed in upland and depressional areas, was conducted using a 6-yr rotation of corn (Zea mays L.) and cotton to determine the CT and DT effects on SOC contents and residue characteristics returned to the soil. Annual soil samples were collected from 50 locations per field at 0- to 3- and 3- to 15-cm. After 6 yr under CT, residue accumulation promoted a significant SOC increase in the 0- to 3-cm depth in the upland soil series (about 0.7 Mg SOC ha -1 ). The lack of residue mixing in the 3- to 15-cm depth in upland soils under CT, however, resulted in a significant SOC content decline at this depth (1.25-2.51 Mg SOC ha -1 ). There was no significant SOC content change in soils under CT formed in depressional areas or in all soils under DT. During 6 yr, 14.8 Mg ha -1 of organic C from both corn and cotton residues was returned to soils under CT, but

Soil erosion on southern Piedmont soils remains a problem without application of sound conservation practices. This study was conducted to compare a no-tillage (NT) system with a conventional-tillage (CT) system in row-cropped land under natural rainfall conditions for six continuous years. Runoff and soil loss were continuously monitored from May 1995 to April 2001 from four erosion plots (7.3 m × 12.2 m [24 ft × 40 ft]) in CT and four plots in NT under a corn (Zea mays L.)-soybean (Glycine max L.) rotation in a Mecklenburg sandy clay loam and Enon clay loam (fine mixed, active, thermic, Ultic Hapludalfs) at a Piedmont location. Runoff was significantly less for NT than for CT in three study years; in the other three years no differences between treatments where found. The NT six-year runoff average was 33% lower than the six-year runoff average of CT. The tolerable soil loss level of 7.0 Mg ha-1 y-1 (3.1 tn ac-1 yr-1) was exceeded in CT in four study years, while annual NT losses were always below 7.0 Mg ha-1 y-1 The six-year soil loss average was 74.7 Mg ha-1 (33.3 tn ac-1) and 2.6 Mg ha-1 (1.2 tn ac-1) for CT and NT, respectively. In CT, most of the soil lost during the six-year study period occurred during rain storms of high intensity. No-till was highly effective at protecting against soil loss during these rain storms.

Shallow sampling depths are recommended for collecting soil samples for lime and fertilizer recommendations when using conservation tillage. Some subsoiling implements used to disrupt the compacted horizon in some southeastern USA coastal plain soils can also disturb the surface soil. Our objective was to compare sampling depths for lime, P, and K recommendations in a conservation tillage system that includes paratill subsoiling. One-half of a 14-acre field was managed with conventional tillage. The other half was managed with conservation tillage which consisted of using a six-shanked paratill followed by planting. Soil samples from 0 to 3 inches and 0 to 6 inches were collected for four years on each side of the field around points in a 50-ft × 50-ft grid. The field was in a corn (Zea mays L.)-cotton (Gossypium hirsutem L.) rotation. Soil P and K concentrations differed for sampling depths in most years for both tillage systems. Generally, these differences were small but fertilizer P and K recommendation rates for the two sampling depths were the same more often for conventional tillage than for conservation tillage. After a lime application in 2002, pH of the soil 0 to 3-inch depth in the conservation tillage half of the field was 5.89 in 2003, 6.07 in 2004, and 6.29 in 2005 while the pH of the soil collected from the 0 to 6-inch depth was about 6.1 each year. When using the 0 to 6-inch sampling depth in fields managed with this conservation tillage system, it appears a separate sample for soil pH from a shallower depth may be beneficial in the years subsequent to a lime application.

In the southeastern U.S. Coastal Plains, supplemental irrigation is required to reduce the impact of short-term droughts and yield-reducing plant water stress that can occur at least biennially. Sprinkler irrigation is commonly used to water agronomic crops in the region. Microirrigation is typically used for high value fruit and vegetable crops. In recent years and at some locations, microirrigaiton combined with conservation tillage has been implemented for agronomic crop production to help conserve soil moisture. In this research, we investigated the feasibility of planting corn (Zea Mays L) in narrow rows over subsurface drip irrigation (SDI). Our specific objectives were to 1) compare narrow-row corn yields using surface and subsurface drip irrigation with laterals spaced at 1 and 2 m; 2) compare the effects of pulsed SDI applications to move irrigation water farther away from the laterals on narrow-row corn yields; and 3) evaluate the impact of corn row distance from SDI laterals on plant biomass, nitrogen, and yield components. Corn was planted in 0.38-m rows on an existing subsurface drip irrigation system with laterals installed 0.30 m below the soil surface and spaced at 1 and 2 m apart. Surface drip irrigation was installed at both lateral spacings to compare with the SDI treatments. Irrigation was applied weekly as required to meet the crop water demands. All nutrients were applied through the subsurface drip irrigation system. Corn yields for 2003 ranged from 4301 to 5420 kg/ha, while in 2004 the yields were greater and ranged from 4452 to 6329 kg/ha. No significant differences were observed between the SDI and surface drip irrigated treatments. Corn yields from the pulsed SDI treatments were not significantly different from non-pulsed treatments. Early season whole plant biomass was significantly higher for the 2-m SDI lateral spacing, but there were no significant biomass differences at later growth stages. Corresponding whole plant N concentrations were significantly higher for the 1-m SDI lateral spacing in 2004. Grain N, ear length, and ear weight were not significantly different at harvest for SDI lateral spacing. We found that the distance of the corn rows from the SDI lateral greatly influenced the crop growth and grain yield. Plant biomass, whole plant N, ear length, and grain weight all decreased significantly with distance from the SDI laterals. These results show a great deal of variability among rows when corn is grown in 0.38-m spacing over SDI laterals for wider row crops. Higher plant populations placed closer to the laterals may increase productivity.

Reliable agronomic and fibre quality data generated in Upland cotton (Gossypium hirsutum L.) cultivar performance trials are highly valuable. The most common strategy used to generate reliable performance trial data uses experimental design to minimize experimental error resulting from spatial variability. However, an alternative strategy uses a posteriori statistical procedures to account for spatial variability. In this study, the efficiency of the randomized complete block (RCB) design and nearest neighbour adjustment (NNA) were compared in a series of cotton performance trials conducted in the southeastern USA to identify the efficiency of each in minimizing experimental error for yield, yield components and fibre quality. In comparison to the RCB, relative efficiency of the NNA procedure varied amongst traits and trials. Results show that experimental analyses, depending on the trait and selection intensity employed, can affect cultivar or experimental line selections. Based on this study, we recommend researchers conducting cotton performance trials on variable soils consider using NNA or other spatial methods to improve trial precision.

A new manure treatment technology developed as an alternative to anaerobic lagoons on swine (Sus scrofa domesticus )f arms includes solid-liquid separation and subsequent recovery of soluble P as calcium phosphate from the wastewater. The objective was to determine the agronomic effectiveness of this calcium phosphate material. A greenhouse study was conducted with annual ryegrass (Lolium multiflorum Lam.). Three fertilizer materials were evaluated: the recovered P in two particle sizes (0.5–1.0 and 2.0–4.0 mm), and commercial triple superphosphate (TSP). Fertilizer rates were 0, 22, 44, 88, and 176 mg P kg 21 soil. Three harvests of the ryegrass were made at 2-wk intervals. Total P uptake increased linearly with application rate for all three fertilizer materials. At the highest application rate, total P uptake was 37.8 mg pot 21 for TSP, 26.2 mg pot 21 for the recovered P with small particle size, and 9.0 mg pot 21 for the recovered P with large particle size. Chemical analysis of the recovered P material revealed that over 99% of the P2O5 in the recovered calcium phosphate was plant available P, mostly as citrate-soluble. Mehlich-3 extractable soil P at the end of the experiment indicated that little of the large particle size of recovered P material dissolved and became available during this short 10-wk study. The recovered calcium phosphate appears to have potential as a fertilizer source.

Water availability is a major factor infl uencing cotton cultivar performance and sustainable cotton (Gossypium hirsutum L.) production in the southeastern USA. An increased understanding of the response of diverse cotton germplasm lines to supplemental irrigation could aid in future efforts to develop cultivars targeted to irrigated or dryland environments. In this study, 13 germplasm lines were selected from the Pee Dee (PD) germplasm collection and evaluated to measure the effect of supplemental irrigation on a number of agronomic and fi ber quality traits important to cotton production systems. Most PD germplasm lines receiving supplemental irrigation had increased plant height and lint percent, while boll weight, seed index, fi ber length, fi ber strength, uniformity index, and micronaire decreased. Cultivars PD-2 and FM-966 did not show a signifi cant response to supplemental irrigation for any of the traits measured. In contrast, PD5377 and PD93009 showed differential responses to supplemental irrigation for 5 out of the 12 traits measured. This study shows the importance of comparing individual genotype response to supplemental irrigation for agronomic and fi ber quality traits to effi ciently target genotypes for irrigated or dryland environments.

Soil organic carbon (SOC) sequestration is an important process to mitigate CO 2 emissions. Our objectives were to determine the rates of C sequestration and to determine if the SOC pool was at or approaching equilibrium in plots under long-term (24-yr) conservation (CT) and disk tillage (DT) management. The plots were Norfolk loamy sand (fine-loamy, kaolinitic, thermic, Typic Kandiudult) and were under a row crop rotation. All plots received annual subsoiling, while only plots under DT were surface disked. Soil cores were collected to 90 cm deep. After 24 yr, the only significant increase in SOC occurred in CT plots at a 0- to 5-cm depth. The SOC pool in plots under DT was at a near-steady state, while the SOC pool under CT was not at equilibrium. This supports the conclusion that CT is an effective countermeasure to offset atmospheric CO 2 emissions.

There currently are no data on using reduced tillage for flax (Linum usitatissimum L.) production when double-cropped after cotton (Gossypium hirsutum L.) in the southeastern USA. This study evaluated how tillage and subsoiling influenced double-cropped flax and cotton productivity and quality under conditions in the southeastern USA. An irrigated study on a loamy sand soil (Eunola loamy sand) was conducted beginning in spring 2001 through spring 2003. Treatments evaluated in both crops were subsoiling (subsoiled to 30-cm or none) and tillage (chisel plow to 20-cm plus disking, disking only, and no tillage). Standard fiber test methods were used to evaluate treatment effects on fiber properties. Subsoiling increased the cotton and flax yield. Cotton yields were not influenced by tillage treatment while flax dry plant matter yields were greater for chisel and disk treatments compared with the no-tillage treatments. Fiber properties, cotton micronaire, fiber length, and fiber length uniformity, and flax fiber strength were impacted by tillage. Our results indicate that for this double-crop system, no tillage with subsoiling is a viable practice for cotton but further research is needed to improve flax productivity with this management practice.

A loamy sand Acrisol (Aquic Hapludult) that had been microirrigated for 6 years became so severely compacted that it had root limiting values of soil cone index in the Ap horizon and a genetic hardpan below it. Deep and surface tillage systems were evaluated for their ability to alleviate compaction. Deep tillage included subsoiling or none. Both deep tillage treatments were also surface tilled by disking, chiseling, or not tilling. Subsoiling was located in row or between rows to avoid microirrigation tubes (laterals) that were buried under every other mid row or every row. Cotton (Gossypium hirsutum) was planted in 0.96-m wide rows. Cotton yield was improved by irrigation from 485 to 1022 kg ha � 1 because both 2001 and 2002 were dry years. Tillage loosened the soil by an average of 0.5–1.3 MPa; but compacted zones remained outside tilled areas. Subsoiling improved yield by 131 kg ha � 1 when performed in row where laterals were placed in the mid rows; but subsoiling did not improve yield when it was performed in mid rows. For subsurface irrigation management in these soils, the treatment with laterals buried under every other mid row was able to accommodate in-row subsoiling which improved yield; and this treatment was just as productive as and had been shown to be less expensive to install than burying laterals under every row. Published by Elsevier B.V.

Tillage affects the ability of coarse-textured soils of the southeastern USA to sequester C. Our objectives were to compare tillage methods for soil CO2 flux, and determine if chemical or physical properties after 25 years of conventional or conservation tillage correlated with flux rates. Data were collected for several weeks during June and July in 2003, October and November in 2003, and April to July in 2004 from a tillage study established in 1978 on a Norfolk loamy sand (fine-loamy, kaolinitic, thermic Typic Kandiudults). Conventional tillage consisted of disking to a depth of approximately 15 cm followed by smoothing with an S-tined harrow equipped with rolling baskets. Conservation tillage consisted of direct seeding into surface residues. Flux rates in conservation tillage averaged 0.84 g CO2 m � 2 h � 1 in Summer 2003, 0.36 g CO2 m � 2 h � 1 in Fall 2003, 0.46 g CO2 m � 2 h � 1 in Spring 2004, and 0.86 g CO2 m � 2 h � 1 in Summer 2004. Flux rates from conventional tillage were greater for most measurement times. Conversely, water content of the surface soil layer (6.5 cm) was almost always higher with conservation tillage. Soil CO2 flux was highly correlated with soil water content only in conventional tillage. In conservation tillage, no significant correlations occurred between soil CO2 flux and soil N, C, C:N ratio, pH, bulk density, sand fraction, or clay fraction of the surface 7.5 cm. In conventional tillage, sand fraction was positively correlated, while bulk density and clay fraction were negatively correlated with soil CO2 flux rate, but only when the soil was moist. Long-term conservation tillage management resulted in more uniform withinand across-season soil CO2 flux rates that were less affected by precipitation events. # 2005 Elsevier B.V. All rights reserved.