Search Results
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.
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.
Composted poultry litter (PL) containing 2.98% N was hand-applied to plots in a split-plot design with 3 replications. Application frequency (total, split) was the major plot and rate (0, 10.9, 21.7, and 43.6 Mg·ha-1) was the sub-plot. Rate was based on total N content of the PL and N requirement for maximum sweet com production. Comparisons were made with a fertilizer blend (FB) containing 23.8N-4.3P-4.1K at a total rate of 564 kg·ha-1 in split applications. Leaf area and average ear weight of sweet com ('Merit') were not affected by frequency or rate. Increasing PL rate from 10.9 Mg·ha-1 to 21.2 Mg·ha-1 increased yield by 3128 kg·ha-1. An increase to 43.6 Mg·ha-1 decreased yield which was probably due to an observed reduction in plant stand. When comparing FB with 10.9 Mg·ha-1PL, the yields were equal. Plant P and K concentrations were increased linearly by PL rate. There were no differences in % N or mg·kg-1Ca and Mg. The highest soil N03-N concentrations in the 15- to 30-cm depth range were produced by 43.6 Mg·ha-1PL (15 mg·kg-1 and FB (35 mg·kg-1. Only the high litter rate increased soil NO3-N below 30 cm As PL rate increased, there was a corresponding increase in soil P. There was a linear increase in soil K from 60 to 200 mg·kg-1 as rate increased. A linear decrease in pH was noted when PL rate increased. Soil EC was almost 2 times higher in the 43.6 Mg·ha-1 PL plots than the next highest rate (275 vs. 150 umhos·cm-1).
Composted poultry litter (PL) containing 2.98% N was hand-applied on individual plots in a RCB design with 3 replications. Rates (0, 8.2, and 16.3 Mg·ha-1) were based on N content of the PL and requirement for maximum tomato production. Comparisons were made with a fertilizer blend (FB) containing 558 kg·ha-1 of 14.1N-5.7P-9.2K applied in split application. `Summer Flavor 5000' tomato plants were hand-planted 46 cm apart in rows spaced 3 m apart. Plant volume and average fruit weight were not influenced by any treatment. A 5920 kg·ha-1 yield increase was noted when PL rate was increased from 0 to 8.2 Mg·ha-1. Total yield was further increased 2757 kg·ha-1 by doubling the PL rate. Yields due to FB were lower but not significantly when compared to PL rates. This decrease in yield could possibly be attributed to FB lowering soil pH to borderline levels for production (5.7) while litter rates had little effect on pH. No differences in leaf P and K were measured. Both rates of PL decreased leaf Ca but increased Mg as rate increased. There was no difference in leaf N, P, K, Ca, or Mg when zero PL and FB were compared. FB increased soil NO3-N in the 0- to 30-cm depth zone more than the PL treatments. When comparing the highest PL rate to the lowest, there was almost a one and one-half time increase in residual soil K at the 0- to 15-cm soil depth. PL increased soluble salts only in the 0- to 15-cm soil depth, however, levels were low.
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.
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 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.
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.
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.
Abstract
‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) plants were grown for 3 years under a sodic irrigation regimen. Mulched and non-mulched plants were irrigated by one of three methods: one drip emitter at the base of the plant, two drip emitters on either side of the plant, or low-volume spray emitter (LVSE). There was a mulch × irrigation treatment interaction. Mulch increased the growth of drip-irrigated plants but not LVSE-irrigated plants. Salt-induced leaf chlorosis and necrosis was only evident on plants with no mulch and irrigated with two emitters. Under mulched soil, K, Na, Mg, Cl, electrical conductivity (ECe), and Na adsorption ratio (SAR) levels were several times lower and uniform throughout the soil profile compared to the non-mulched treatments. Maximum root-zone salinity was 3.7 dS·m−1 for two emitters without mulch and a minimum of 0.5 dS·m−1 for one emitter with mulch.