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Hot water extraction (HW) is time‐consuming, highly variable, and losing popularity as the standard method for estimating plant‐available boron (B) in soil. Proposed alternatives are not widely used and guesstimation is replacing assessment at many soil test facilities. Mehlich 3 is increasingly promoted as a universal extractant, and diethylenetriaminepentaacetic acid (DTPA)–sorbitol and pressurized hot water (PHW) are effective and comparable to hot water extraction but also simpler and easier. Mehlich 3 B extraction has been compared mainly to hot water extraction. Because Mehlich 3 usage would be limited to neutral to acid soils, this study used a limed acid Darco loamy fine sand (loamy, siliceous, semiactive, thermic Grossarenic Paleudult) from eastern Texas to which 10 rates of B were applied followed by either incubation without plants or planting to alfalfa in greenhouse pots. Mehlich 3 extraction of soils obtained from a long‐term experiment on Darco soil from which alfalfa yield respons...

Nitrogen is an important agronomic input for bermudagrass production in the southern USA. Fertilizers that can efficiently provide N to grass pastures and hay meadows are an important issue because of increasing costs and environmental problems associated with N losses. This experiment was designed to determine the effectiveness of various N sources on 'Coastal' bermudagrass [Cynodon dactylon (L.) Pers.] production and N uptake efficiency. Nitrogen was applied at 0, 45, 90, and 135 kg ha -1 harvest -1 as urea-ammonium nitrate (UAN), urea, ammonium nitrate (AN) and ammonium sulfate (AS) on Gallime (Glossic Paleudalf) and Lilbert (Plinthic Paleudult) soils. Mixtures of S with UAN and of Ca and B with urea were also evaluated. Bermudagrass was periodically harvested and subsampled for total N analysis. At termination of the study soil samples were collected for pH and extractable NO 3 -N analyses. Bermudagrass yield responses to N sources were significant only in the Gallime soil. In this soil, AN and AS increased yields and resulted in greater N uptake compared to urea and UAN. Lilbert soil showed no effect of N sources on dry matter (DM) production. There was a yield response to N rates and maximum bermudagrass production was generally achieved at the 90 kg ha -1 N rate regrowth -1 . Fertilizer efficiency declined as the N rate was increased. Soil acidity increased in response to N application, particularly for the AS treatments. Selection of N sources and rates should be carefully planned to avoid detrimental effects on soil acidity and, consequently, fertilizer efficiency.

Annual ryegrass (Lolium multiflorum Lam.) is increasingly being planted under irrigation as forage for stocker cattle in south central USA, but fertilizer recommendations for maximum production are not well defined. Labile N and P are generally deficient in this region's calcareous soils; K availability is usually considered adequate for plant growth. Growth responses of annual ryegrass to a factorial array of five levels of N and four levels of P were studied for 3 yr on a Knippa clay soil (fine, mixed, superactive, thermic Vertic Calciustolls). Responses to N and P were generally curvilinear, but they also had a strong linear component in Year 1. Increments of growth responses to levels of fertilizer above 269 kg applied N or 39 kg applied P ha -1 were relatively small. Response surface models projected maximum annual dry matter yields that averaged 9.23 t ha -1 and were associated with predicted requirements for applied N and P that averaged 488 and 61 kg ha -1 , respectively. Economically optimal levels of applied N were predicted to range from 250 to 315 kg ha -1 ; the predicted economically optimal range for applied P was 31 to 41 kg ha -1 . Nitrogen concentration in ryegrass forage increased as applied N increased. The data suggest that fertilizing vegetative ryegrass to maintain N in leaf tissue ≥32 g kg -1 provides economically optimal growth for both the ryegrass crop and the young cattle grazing it.

Information about dinitrogen (N 2 ) fixation and transfer is needed to determine potential benefits from growing binary mixtures of alfalfa (Medicago saliva L.) and hybrid bermudagrass [Cynodon dactylon (L.) Pers.] on Coastal Plain soils of the USA. Our objectives were to quantify N 2 fixed by alfalfa and transferred to bermudagrass. 'Alfagraze' alfalfa was grown at row spacings (RS) of 23, 46, 69, and 91 cm in a mixed stand with 'Coastal' bermudagrass on a Darco loamy fine sand (loamy siliceous, semiactive thermic Grossarenic Paleudult). The mixed stand was fertilized with 0, 28, 56, 84, and 112 kg N ha -1 applied for each bermudagrass regrowth. Isotope dilution was used to estimate N 2 fixation and subsequent transfer to bermudagrass in the zero-applied N plots. Wider alfalfa RS significantly increased bermudagrass yields. Higher N rate (NR) significantly improved bermudagrass yield during cool temperature and drought stress periods in 1994 and 1996. Narrower RS and higher NR significantly increased alfalfa production. Legume N derived from the atmosphere ranged from 42 to 91% and the fixed N yield ranged from 80 to 222 kg N ha -1 yr -1 . Bermudagrass N derived from atmospheric N 2 fixation ranged from 1.0 to 77%, and the transfer N yield (TNY) was ≤18 kg N ha -1 yr -1 . Results varied depending on harvest date, year, treatment, and grass yield. Alfalfa RS had little effect on TNY. The low bermudagrass yield and subsequent TNY in this binary forage production system suggest that monoculture alfalfa may be the best approach for managing alfalfa on Coastal Plain soils.

Alfalfa pasture has not been sustainable on the coastal plain of the United States because of its intolerance to soil acidity. This study examined the responses of alfalfa metabolism to differential amendments of acid soil and to serial harvesting. The soil was spatially amended with different quantities of flue gas desulfurization sludge and gypsum after liming to pH 7. The serial harvests oscillated the RNA synthetic activity of glutamate dehydrogenase (GDH) from an oxidized to a reduced state irrespective of the soil amendments. The amplitudes of the redox cycles changed from one harvest to the next, thus demonstrating improved regrowth persistence. The chlorophyll, hexose, nucleotide, and protein contents, and the fructose‐1, 6‐bisphosphatase activity, decreased and fluctuated inconsistently in the successive cuttings. Consideration of the metabolic responses per harvest showed that the alfalfa had optimized saccharide metabolism in the first harvest, optimized RNA metabolism in the second ha...

Alfalfa (Medicago sativa L.) may support better stocker calf gains than common bermudagrass [Cynodon dactylis (L.) Pers.] in the southern USA. Yearling heifers (Bos taurus 3 B. indicus) grazed each type of pasture for 2 yr on a Coastal Plain soil in southwest Arkansas. Alfalfa stand counts declined linearly with time after planting. Spring forage mass was greater for alfalfa than bermudagrass, but summer dormancy of alfalfa resulted in a summer forage mass advantage for bermudagrass. Bermudagrass provided a longer grazing season (115– 168 d for bermudagrass vs. 66–156 d for alfalfa, P , 0.01), more animal grazing days (1040–1452 vs. 594–1221 d, P , 0.01), and fewer grazing interruptions than alfalfa. Average daily gain (ADG, 462 vs. 319 g d 21 , P , 0.05) and total liveweight gain (664 vs. 447 kg ha 21 , P , 0.05) were greater for alfalfa than bermudagrass in Year 2. In both years, heifers grazing alfalfa made the same amount of liveweight gain in less time than heifers grazing bermudagrass. The bermudagrass system had a negative net return across the trial period. Net return for the alfalfa system was dependent on the value of harvested hay. When alfalfa hay valuereached $95 Mg 21 of dry matter (DM), net return was greater for the alfalfa system than for the bermudagrass system ($59 vs. $2148 ha 21 , P , 0.05). On a Coastal Plain soil, renovation of common bermudagrass to alfalfa pasture can be economically feasible under a dual stocker/hay production system.

Pressurized hot water and DTPA-Sorbitol are two relatively new, proposed alternative soil boron (B) extraction methods for which no data on yield or plant nutrient uptake have been reported for validation. Both methods initially have shown significant correlation with the hot water extraction method in untreated soils as well as soils incubated with various levels of B. The objective of the research was to extract samples of B-treated soils by using all three extraction methods and correlate the B values obtained to yield, B tissue concentration, and total B removal of alfalfa (Medicago sativa). Greenhouse and field experiments on alkaline and limed acid soils naturally low in hot water-extractable B were conducted to test alfalfa response to B fertilizer. In the greenhouse, highly significant relationships exist between plant uptake and extractable B with all three methods at varying levels of applied B, but no alfalfa yield response was observed. All three methods result in accurate predictions of plant B tissue concentrations and total B removal. The field experiment exhibited a significant positive relationship between total alfalfa yield and extractable B using hot water and pressurized hot water extractions. Extractable B using DTPA-Sorbitol was not related to total alfalfa yield in the field experiment. This work, coupled with the earlier incubation studies, supports the pressurized hot water extraction method as an improvement over hot water in diverse soil types. The lack of relationship in the acid soil supports DTPA-Sorbitol as an improvement over hot water in alkaline soils.

Serious challenges associated with hot water extraction, the standard extraction method for water‐soluble boron (B), limit its use in commercial soil‐testing laboratories. Several alternatives to make B testing more practical have been proposed and studied; none of the alternatives have readily replaced the hot water method. Two relatively new, promising B extraction methods are pressurized hot water and DTPA‐Sorbitol. Very little reported work compares B extraction values obtained from the standard hot water extraction method and these two alternative methods. This study was conducted to complete an initial step in validating new procedures—extracting the designated nutrient from fertilized, incubated soils by using standard and alternative extraction methods and comparing the resulting values. The three extraction methods were used to extract B from samples of calcareous sand and silt loam soils and limed, loamy fine sand, all which had been treated with 10 levels of B (0–8 mg kg−1) and incubat...

Alfalfa (Medicago sativa L.) is rarely grown on the Coastal Plain of southern United States. Production problems include infertile acid soils, inadequate pest control, and high humidity with frequent rainfall events that preclude adequate alfalfa hay drying conditions in spring. Research to overcome soil fertility problems included evaluation of nitrogen (N) rates over alfalfa row spacings and limestone and boron rates in split plot studies; phosphorus (P) rates using a randomized complete block design on eight soil series; and potassium (K), magnesium (Mg), and sulfur (S) rates and zinc (Zn), copper (Cu), and molybdenum (Mo) rates in central composite, rotatable design studies. Field-scale demonstrations were conducted to verify data from small plot research. Results indicate little need for N fertilization of alfalfa on Coastal Plain soils except possibly under cool or dry surface soil conditions. Increasing the between-row planting distance from 23 to 69 cm lowered alfalfa dry matter yield by 2.1 Mg ha 21 the seedling year. Alfalfa yielded 11 Mg ha 21 at all row spacings in the drought-affected third year. Dry matter yield was maximized at 49 - 73 kg applied Ph a 21 on soils testing below 19 mg P kg 21 by the NH4OAc-EDTA extraction method. The alfalfa stand was lost after one season on plots not fertilized with K. Applied Mg, S, Zn, Mo, and Cu had no significant effect on alfalfa yield. Dry matter increased . 5M g ha 21 as pH was increased from 6.0 to 7.5. Boron applied at 3.4 kg ha 21 increased alfalfa yields 3.9 Mg ha 21 . With improved methods for site selection and adequate fertility, sustainable economic production of alfalfa is possible with rain-fed conditions on selected, limed Coastal Plain soils.

Plants cultivated on acid soils that contain toxic levels of Al3+ usually produce low yields. A multi-factorial treatment of gypsum (G), boron (B), and limestone (Lm) was applied to such soil in order to determine the biochemical basis of the best management plan for ameliorating the soil acidity for sustainable growth of alfalfa. The alfalfa shoots were subjected to analysis for hexose, protein, nucleotide, and chlorophyll (Chl) contents, fructose 1,6-bisphosphatase (FBPase) activity, and the RNA synthetic activity of glutamate dehydrogenase (GDH). Hexose and protein contents of control alfalfa without B and G, but with Lm (672 g m−2) amendment were 0.87 and 38.30 g, respectively, per kg shoot. Increasing the G doses at fixed moderate doses of 0.15 and 0.30 g m−2 B decreased the FBPase activity by ∼53 and ∼31 %, respectively. However, increasing the B doses at higher fixed G (1 kg m−2= G1.0) increased the FBPase activity by ∼91 % thus indicating that G1 optimized the saccharide metabolism by neutralizing the soil acidity. In the absence of B, increasing the G doses also maximized the hexose and Chl contents, but minimized the nucleotide amount. In the absence of G, increasing the B doses maximized the RNA synthetic activity of GDH, but lowered the hexose and Chl contents as well as the FBPase activity without affecting the protein contents, thereby permitting the selection of B (0.45 g m−2) with Lm as the best amendment for the sustainable growth of alfalfa. Treatment with 0.45 g B and 0.5 kg G (= G0.5) induced the strongest B-Ca antagonism by maximizing the hexose and Chl contents but severely suppressing the FBPase activity and the RNA synthetic activity of GDH. Therefore, the coordinate optimization of saccharide metabolism through the G-dependent neutralization of soil acidity, and of RNA metabolism through the B-dependent detoxification of Al3+ are the biochemical options for the mitigation of the adverse effects of soil acidity for the optimization of sustainable alfalfa production.

Large and repeated manure applications can exceed the P sorption capacity of soil and increase P leaching and losses through subsurface drainage. The objective of this study was to evaluate the fate of P applied with increasing N rates in dairy wastewater or poultry litter on grassland during a 4-yr period. In addition to P recovery in forage, soil-test phosphorus (STP) was monitored at depths to 180 cm in a Darco loamy sand (loamy, siliceous, semiactive, thermic Grossarenic Paleudults) twice annually. A split-plot arrangement of a randomized complete block design comprised four annual N rates (0, 250, 500, and 1000 kg ha(-1)) for each nutrient source on coastal bermudagrass [Cynodon dactylon (L.) Pers.] over-seeded with ryegrass (Lolium multiflorum L. cv. TAM90). Increasing annual rates of N and P in wastewater and poultry litter increased P removal in forage (P = 0.001). At the highest N rate of each nutrient source, less than 13% of applied P was recovered in forage. The highest N rates delivered 8 times more P in wastewater or 15 times more P in poultry litter than was removed in forage harvests during an average year. Compared with controls, annual P rates up to 188 kg ha(-1) in dairy wastewater did not increase STP concentrations at depths below 30 cm. In contrast, the highest annual P rate (590 kg ha(-1)) in poultry litter increased STP above that of controls at depth intervals to 120 cm during the first year of sampling. Increases in STP at depths below 30 cm in the Darco soil were indicative of excessive P rates that could contribute to nonpoint-source pollution in outflows from subsoil through subsurface drainage.

Since 1994, urban-absentee landowners have dominated rural landownership in Texas. This landownership change has created potential environmental problems associated with natural resource management. Few of the new landowners have any formal training in the basics of the soil–plant–animal interface. The solution may be to develop a vehicle that provides the new class of landowners with basic information regarding natural resource management. Faculty members from the Texas AM and (ii) introduce the workshop participants to the educational resources available to them through the land-grant university system. To determine effectiveness of the program, pretests and posttests were administered to the workshop participants. To date, pretest scores have averaged 63.8 (D average), whereas posttest scores have averaged 80.3 (B average). Exit surveys were also conducted to determine the attitude of the workshop participants regarding the overall quality of their experience. The popularity of the workshop is such that, since the inception of the first workshop (2001), subsequent workshops have been booked nearly 1 year in advance. Given the combination of learning environment, mix of classroom and field laboratory exercises, and nonthreatening scientific presentations, we have little doubt that the Pasture and Livestock Management Workshop will continue to be a popular program with urban-absentee landowners.

Slow reactivity of coarse-grade ag-lime surface applied on soils established to perennial grasses led us to study the effectiveness of finer-ground limestone. Legume production and soil pH were used to evaluate treatments in a glasshouse experiment that included soil-incorporated and surface-applied limestone at increasing rates and effective calcium carbonate equivalence (ECCE) percentages that can be converted to kilograms of effective liming material (ELM) Mg−1. Excessive rates of limestone and the highest ECCE percentage materials decreased clover yield when applied and left on the soil surface. Comparison of ECCE 62% limestone with ECCE 100% limestone verified the initially greater efficiency of the finer lime for forage production. Four to seven years after application, annual ryegrass yields were similar for the ECCE 62% and 100% limestone materials. Seven years after the final limestone treatment, ECCE 100% limestone maintained soil pH 0.3 unit higher than pH due to the same rate of ECCE 62%. At t...

Soil acidity and fertility management are critical for crop production on Coastal Plain soils of the southern and southeastern USA. Grasses and legumes are the primary crops grown on these soils. Hybrid bermudagrass (Cynodon dactylon (L.) Pers.) and bahiagrass (Paspalum notatum) are the major warm-season grasses while annual ryegrass (Lolium multiflorum Lam.) is the dominant cool-season grass. Bahiagrass tolerates acidity and low soil fertility. Bermudagrasses tolerate moderate soil acidity levels and readily respond to N, P, and K fertilization. Annual ryegrasses are highly responsive to limestone, N, and P. High rates of ammonium N applied for grass production rapidly increase acidity due to nitrification in these low-buffer-capacity soils. Liming these soils to increase pH improves P use efficiency and forage production. Fertilizer P increased soil test P 38% as soil pH was raised from 4.5 to 6.2 in a Lilbert loamy fine sand (thermic Arenic Plinthic Paleudult). Forage legume crops respond favorably to ...

Alfalfa (Medicago sativa L.) is a rare forage crop on Coastal Plain soils. Acid soils, wet conditions, and the prevalence of perennial, warm-season grasses limit alfalfa production. Development of grazing-tolerant varieties raised interest in growing alfalfa on the Coastal Plain. This three-year dryland field study was conducted to evaluate coincident production of Alfagraze' alfalfa and 'Coastal' bermudagrass [Cynodon dactylon (L.) Pers.] as a sustainable forage system. Limestone (effective calcium carbonate equivalence ECCE 72%) at a rate of 6.1 t ha -1 was incorporated by roto-tilling 15 cm deep in an established sod of Coastal bermudagrass on a Darco loamy fine sand (loamy, siliceous, thermic Grossarenic Paleudults) in late winter 1990, with an additional 3 t ha -1 surface-applied in June 1991. Alfalfa was seeded in October 1990 at 23, 46, 69, and 92 cm between rows in main plots of a split-plot design. Nitrogen rates from 0 to 112 kg ha -1 in increments of 28 kg ha ' were applied to subplots for every bermudagrass regrowth cycle. Other plant nutrients (including P, K, Mg, S, B, Zn, and Cu) were applied at rates considered adequate for alfalfa on a low-fertility soil. Yield of alfalfa at the 23-cm row spacing in 1991 was 8.8 t ha -1 and declined to 6.7 t ha ' at 69 cm (P = 0.05), while yield of bermudagrass increased from 3.2 to 5.7 t ha -1 , respectively, at these row spacings. In 1992, alfalfa yield increased an additional 2.2 t ha -1 at each row spacing, with a compensating decline in bermudagrass production. Alfalfa yielded 11 t ha - 1 at all row spacings in 1993, despite a midseason drought, while bermudagrass yield was

Excess levels of plant nutrients are being applied to soils when effluent from waste treatment lagoons is repeatedly irrigated on small parcels of land adjacent to large poultry operations. Therefore, field research was conducted at College Station and Overton, Texas, to evaluate the effects of poultry lagoon effluent on soil, vegetation and surface runoff quality. Two cropping systems, bermudagrass and a bermudagrass/ryegrass rotation, and three application rates, 0, 538 and 1076 kg N/ha/yr, were studied in experimental plots 1.2 m wide and 2.4 m long, from February 1995 to April 1996. Each treatment was replicated three times in a modified random block design. The site located near College Station was on a Ships series clayey soil with a 0.5% slope. The site near Overton was on a Bowie series fine-loamy soil with a 5.0% slope. Nutrient increases in the soil were directly related to effluent nutrient levels and background soil concentrations. Nitrate and potassium concentrations significantly increased throughout the soil profile to a depth of 914 mm at the 1076 kg N/ha/yr rate at Overton. The 1076 kg N/ha/yr rate did not significantly increase yields on either crop system above the yields at the 538 kg N/ha/yr rate. The bermudagrass/ryegrass crop was the most effective in nutrient uptake with 51% N, 43% P and 35% K taken up by the vegetation at the 538 kg N/ha/yr rate. Nutrient losses in the surface runoff were directly related to slope. Nitrogen losses in the surface runoff at the Overton site were three to five time higher than at the College Station site. However, average nutrient concentrations in the surface runoff at the two sites were similar with large standard deviations.

Expanded use of sulfur (S)‐free fertilizers and copper (Cu)‐free fungicides is likely to increase plant deficiencies of these essential elements. Zinc (Zn) deficiency occurs more frequently. An effective and reliable means of correcting Zn deficiency in peach trees remains to be documented in Texas. This study was designed to evaluate S, Cu, and Zn treatments on peach trees. Fifteen treatments consisting of combinations of five rates each of S, Cu, and Zn were evaluated using a central‐composite, rotatable design. Each treatment was replicated four times. Sulfur and Cu treatments were applied in January. Zinc treatments were foliar‐applied in March, April, and May. Responses were linear between applied Zn and leaf Zn, applied S and leaf S, and applied S and leaf area. A positive correlation between leaf Cu and leaf N was found. A preliminary study in the greenhouse revealed that both the 12.5 and 25 ppm Cu treatments were toxic. In a succeeding study, no statistical differences among Cu treatment...

The ammonium acetate (NH4OAc)‐EDTA soil phosphorus (P) extraction method was compared to either the Bray‐1 soil P extraction method for non‐calcareous soils or the Olsen soil P extraction method for calcareous soils to predict com and wheat plant tissue P concentration and grain yield responses. The NH4OAc‐EDTA method predicted yield and tissue P concentration responses to P fertilizer applications more accurately than the Olsen method at three of five sites. Both the Bray‐1 and NH4OAc‐EDTA methods were successful in predicting corn and wheat yield responses to P fertilizer applications in non‐ calcareous soils in many locations. However, a direct comparison of extracted soil P levels showed that the NH4OAc‐EDTA method extracted soil P at levels which were more closely related to the Bray‐1 method than the Olsen method.

Acid, sandy soils selected for blueberry production are usually deficient in plant available phosphorus. Fertilizer addition at planting has not been a recommended practice. This research was designed to evaluate potted blueberry (Vaccinium ashei Reade) plant growth response to P applied at establishment and interacted with N applied during the growing season. Four liter containerized ‘Tifblue’ rabbiteye blueberry plants were transplanted into 4.4 kg of 1:1 v/v loamy sand:peat mixture in an 8‐liter container. Preplant P was incorporated into the mixture at 0, 20, 40, 60, and 80 kg/ha rates. Nitrogen was split‐applied post‐plant four times at 60‐day intervals beginning 30 days after blueberry bushes were transplanted. Total N rates were equivalent to 0, 112, 224, or 336 kg/ha. Plants were harvested 270 days after transplanting. Phosphorus at the 60 and 80 kg/ha rates increased plant growth 40 and 31%, respectively. Plant growth responded linearly to increasing N rate. Leaf and stem weight increase...

Limestones ranging from 49 to 100% effective calcium carbonate equivalence (ECCE) are applied to acid soils in the southern Coastal Plains states of the USA. Because of the slow reactivity of low ECCE limestone, we evaluated the effects of finer-ground limestone for surface application on soils producing perennial forages. Limestones with ECCE percentages of 62 and 100 were applied at rates of 0, 2.24 and 4.48 t ha-1 to a Darco loamy fine sand (loamy, siliceous, thermic Grossarenic Paleudult). Boron (B) was applied preplant each year at rates equivalent to 0, 1.12, and 2.24 kg ha-1 to study its effect on plant growth and interaction with limestone. Factorial treatments were arranged in a randomised, complete-block design. An experimental line (RD-3) of rose clover (Trifolium hirtum All.) was overseeded into ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) sod each fall for 3 years. Limestone treatment generally increased clover dry matter yield 3.58t ha-1 over 3 years. Boron and the interaction of B with the finer limestone increased clover yields in 1989 and 1991. Finer limestone increased clover yields at all B rates in 1990. Limestone and B treatments did not affect yield of bermudagrass. Soil pH at 0’5 cm in the lime check plots was lowered from 6.0 in 1989, to 4.8 in 1990 by nitrogen (N) applied to the bermudagrass. During this time, soil pH at 0’5 cm was maintained at 6.2 by ECCE 100 limestone compared to a decline to 5.4 with ECCE 62 limestone. Soil B retention increased as soil pH was elevated. This study indicates that B becomes a crucial consideration when fine limestone is applied to Coastal Plains Ultisols for clover production.

Triploid watermelon (Citrullus lanatus Thunb.) was grown on the same plots in 1990 and 1991 and fertilized with either poultry litter or commercial fertilizer. Additional treatments included bare soil or plots mulched with black polyethylene, and plots with or without spunbonded fabric row covers over both bare soil and mulch. Watermelon yields were unaffected by fertilizer source in 1990 but were significantly higher for poultry litter than for commercial fertilizer treatment in 1991. Polyethylene mulch significantly increased postharvest soil NO3 and leaf N concentrations in 1990 and increased yield and yield components in both years. There were no beneficial effects of row covers on yield in either year, presumably because no early-season freezes occurred.

When poultry litter (PL) is applied to meet the nitrogen (N) needed for plant growth, phosphorus (P) can accumulate, leading to non-point source pollution of surface water. This study was conducted at Overton, Texas on a Bowie fine sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) to investigate the use of warm- and cool-season forage legumes in rotational cropping systems to remove excess P. Cropping systems were: spring legume—fall vegetable (SL-FV), spring vegetable—fall legume (SV-FL), and spring vegetable-fall vegetable (SV-FV). Warm- and cool-season legumes were Iron and Clay cowpea and crimson clover, respectively. Poultry litter rates were 0, 1X, 2X, 4X, and commercial blend (CB) as subplots. Fertility treatments were applied to vegetable plots only. The crop, IX PL and CB rate for each season were: spring 1995—watermelon, 2.2 t·ha-1, 48.8N—12.2P—28K kg·ha-1; fall 1995—turnip, 8.3 t·ha-1, 89.6N—24.4P—28K kg·ha-1; spring 1996—tomato, 6.7 t·ha-1, 100.9N—17.1P—78.5K kg·ha-1. Soil P increased at all depths sampled (0-15, 15-30, and 30-45 cm) as PL rate increased. Residual P from CB was equal to the control. Through spring 1996, soil P concentration in the surface 0-15 cm was increased by all systems. System SV-FL reduced P accumulation by 35.6 mg·kg-1 when compared to SL-FV and 44.7 mg·kg-1 when compared to SV-FV. Residual P continued to increase as PL rate increased. Rate of increase was reduced by a system of SV-FL.

A factored experiment was established at the Texas A&M Univ. Research and Extension Center at Overton in Spring 1995. The objective was to investigate the use of warm- and cool-season legume cover crops in vegetable cropping systems for reducing phosphorus (P) accumulation from poultry litter (PL) and commercial blend (CB) fertilizer. PL rates were based on soil test nitrogen (N) requirement of the vegetable crop and percent N content of the litter. This was considered the 1X rate. Fertility treatments were applied to the vegetable crop only. PL was applied at O, 1X, 2X and 4X rates. CB was applied at recommended rates for N, P, and K. The vegetable crops were: Spring 1995—watermelon; Fall 1995—turnip; Spring 1996—tomato; Fall 1996—collard; Spring 1997—squash. The legumes were: spring—Iron and Clay cowpea; fall—crimson clover. Dry-matter yield of cowpeas and clover was not affected by fertility treatment in any of the years studied to date (Spring 1995, 1996, 1997). Plant concentration of P for both cover crops was increased all 3 years as rate increased. PL applied at the 1X rate maintained P levels in the surface 0—15 cm of soil at 60 mg·kg-1 over the five-season study period. CB maintained levels of P equal to the control. A cropping system of spring vegetable—fall legume greatly reduced P accumulation. A reduction in P was also noted from a system of fall vegetable—spring legume, but not as pronounced. The greatest accumulation was with a system of spring vegetable—fall vegetable.

Phosphorus (P) concentration in surface waters from non-point agricultural sources is an increasing resource management concern. This study was conducted at Overton, Texas, on a Bowie fine sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) to evaluate cool-season legumes for P uptake following poultry litter (PL) application rates on spring vegetables. Treatments were PL rate (0, 1X, 2X, 4X) and a commercial blend (CB) for comparison. Cool-season legumes, consisting of crimson clover, berseem clover, hairy vetch, and red clover, were the subplots. The vegetable crop in Spring 1995 was watermelon. The 1X PL rate was 2.2 t·ha-1 and the CB was 44.8N-0P-32.5K kg·ha-1. Dry matter yield was decreased by the 4X PL rate. Plant P concentration increased linearly as PL rate was increased. The greatest P uptake (4.1 kg·ha-1) was at the 2X rate. Hairy vetch had the greatest yield (1,875 kg·ha-1), plant P concentration (0.53%), and P uptake (9.6 kg·ha-1). PL rate increased soil P concentration at all depths. The least amount of P accumulation was from CB and was equal to the control. Hairy vetch appears to have the capability of removing a greater amount of P and reducing soil concentration when compared to the other legume species tested.

Primary environmental concerns regarding application of poultry litter (PL) for crop production are nitrate leaching into ground water and increased levels of P in the soil that can erode into surface water. This study was initiated to investigate use of warm- and cool-season annual forage crops to remove excess nutrients supplied by PL in rotational-cropping systems on a Bowie fine sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults). PL was applied at one (1×) or two (2×) times the recommended rate in the spring, fall, or spring and fall. Rates were based on N requirement of the crop and percent N in the litter. Comparisons were made to fertilizer blends (FB) and control treatments with no PL or FB. After 3 years of treatments, NO3-N increased at the 122-cm depth by 30 and 50 mg·kg–1 from the 1× and 2× rate, respectively. The greatest accumulation was from FB (72 mg·kg–1). With PL applied in spring only, spring vegetables followed by a fall cover showed a significant reduction in NO3-N leaching and accumulation. Regardless of cropping system, rate, or time of application, P concentration increased by 40 mg·kg–1 in the surface 15 cm of soil when compared to FB. If applied in an environmentally sound manner, PL will be less of a threat to pollution of ground water than similar rates of FB. Applying PL rates sufficient to meet crop needs for N results in P accumulation that can lead to nonpoint source pollution of surface waters.

The potential for east Texas to produce Brassica that could compete favorably with the import market exists. This study was conducted to establish optimum nitrogen and boron rates for 4 Brassica spp. grown on highly leachable east Texas soil, a Bowie series (fine-loamy, siliceous, thermic, Plinthic Paleudult). Broccoli (Brassica oleracea L. Italica, var. Green Comet), cauliflower (Brassica oleracea L. Botrytis var. White Contessa), Chinese cabbage (Brassica rapa L. Pekinensis var. Monument), and Chinese mustard (Brassica rapa L. Chinensis var. What-A-Joy) were field grown using 5 rates of N (0, 50, 100, 150, and 200 kg·ha-1) interacted with 3 rates of B (0, 1.25 and 2.5 kg·ha-1) in a complete randomized design with 3 reps. Harvested broccoli heads increased average head weight (HW), average head size (HS), and total yield (Y) for each increase of N. Cauliflower HW, HS, and Y increased up to 150 kg N ha-1. B supplementation did not statistically affect HW, HS, and Y of broccoli or cauliflower. Chinese cabbage Y increased up to 150 kg N ha-1 and produced less Y at 200 kg N ha-1 than at 50 kg N ha-1. Chinese mustard Y increased 50% for the 50 (kg·ha-1) N over no added N with additional N producing statistically equal Y. B at 1.25 (kg·ha-1) significantly increased cabbage Y, but had no effect on mustard Y.

Soil solarization following previous N application rates of 0, 56, 112, 168 and 224 kg·ha-1 as ammonium nitrate, and one cover crop of-sorghum-sudah (Sorghum bicolor var.) increased yields of turnip foliage (greens) by 3066 kg·ha-1 over the non-solarized treatment. Greater yield was obtained with 56 kg·ha-1 less N with solarization than non-solarization (112 vs 168 kg·ha-1). A blanket N application of 22 kg·ha-1 ameliorated the solarization effect on the 2nd harvest. Solarization had no significant effect on turnip leaf element concentration. Linear and quadratic increases in leaf N occurred as soil N increased. There was also a linear increase in tissue K and Mg due to solarization. No interactive effects were noted. Soil analysis showed salinity (EC) decreased and Ca increased with solarization. An increase in N rates decreased pH, NO3, and Mg, and increased soil salinity and NH4. Solarization had an interactive effect on soil salinity by increasing EC at 0 N and decreasing at 56 to 168 kg N·ha-1.

The increase of the Asian population in Texas has created a demand for specialty vegetables including Chinese cabbage. Chinese cabbage (Brassica rapa L. Pekinensis var. Monument) was grown in a greenhouse to study the main effects of P, K, Ca, Mg, S, Fe, Mn, Zn, B, and Mo on plant growth. A randomized complete block design with 4 replications was used. The elements were incorporated and tested at three rates in soil from the Ap horizon of the Darco series (loamy, siliceous, thermic Grossarenic Paleudult). Treatments consisted of a check, where no nutrients were incorporated, all nutrients incorporated at 1X rates, and all nutrients at 2X rates. Each nutrient was tested individually at the 0 and 2X rates, while the remaining nutrients were held constant at the 1X rate. Analysis of variance indicated plant growth was affected by applications of P, K, S, Zn, B, and Mo. Regression analysis indicated positive growth responses to P, K, S, and Zn, and negative growth responses due to B and Mo applications.

Effect of soil sample treatment on potassium (K) release characteristics of Northern Great Plains soils was studied. Samples of agricultural soils were extracted with neutral normal ammonium acetate for K after selected pretreatment. Field‐moist sub‐soil samples with approximately 100 mg/kg extractable K release nearly double this amount after they were air on oven‐dried prior to analysis. The percentage increase in extractable K in dried soils decreased as the K level in the field‐moist soils increased. At 420 and 500 mg/kg, the extractable K content of air‐dried and oven‐dried soils, respectively, equaled the extractable K content of field‐moist samples. Above these concentrations, drying decreased extractable K. Oven‐drying (60 C) affected extractable K more severely than did air‐drying the soils. Drying and grinding the 15‐ to 30‐cm depth samples significantly increased exchangeable K compared to field‐moist samples. Rehydration of oven‐dried soils to 40% water did not affect extractable K. H...

Copper smelters produce H₂SO₄ during the S scrubbing process, creating a continuing supply of H₂SO₄. Oil refineries use commercial grade H₂SO₄ in alkylation units and the resultant “spent” acid is a waste product available for other purposes. A 2-year field experiment was conducted on two irrigated sites in south-central Montana to evaluate the effectiveness of H₂SO₄ for reclaiming calcareous, salinesodic soils. Treatments included increasing rates of smelter acid, and comparisons with gypsum (CaSO₄ · 2H₂O), spent acid, and feedlot cattle manure in combination with smelter acid. Reclamation effectiveness was evaluated by analysis of saturated paste pH, electrical conductivity of the saturation extract (ECₑ), and sodium adsorption ratio (SAR) values of the soil in the 0- to 15- and 0- to 20-cm depth intervals. Barley (Hordeum vulgare L) was grown both years as a biological test for reclamation. The degree of reclamation improved with increasing acid rate. Barley dry matter yield on plots that received the highest rate of acid was more than four times that of the check the second year. The effect of spent acid was similar to that of smelter acid. Gypsum lowered ECᵉ and pH vlaues more than an equivalent rate of smelter acid, but SAR and barley dry matter yield were improved similarly by both amendments. Feedlot cattle manure plus smelter acid increased barley dry matter yield 40% over smelter acid alone. We propose that this effect is due to the improved soil nutrient status when both amendments are used together.

The acidity of alfisols and ultisols may be unfavorably increased for blueberry production by the use of specific nitrogen (N) fertilizers. Several ammonium containing fertilizers were evaluated for their effects on rabbiteye blueberries (Vaccinium ashei Reade). Rooted ‘Tifblue’ cuttings were grown in a 1: 1 peat: Lilbert loamy fine sand mix for 90 days. After establishment, plants were moved into the glasshouse and fertilized four times at 90‐day intervals with one of six N sources at one of four rates. Nitrogen sources were (NH4)2SO4 (AS), NH4NO3 (AN), urea, urea‐NH4NO3 (UAN), Nitro‐form (NF) and sulfur coated urea (SCU). Rates of N per application were equivalent to 0, 112, 224, or 336 kg/ha. The application of the high rate of each N source reduced plant growth. The 112 and 224 kg/ha N treatments increased growth compared to no nitrogen treatments. When comparing N sources, SCU treatments produced the greatest plant growth and AS treatments the lowest. Sulfur coated urea had less effect on so...