Soil fungal population levels in cotton fields fertilized with poultry litter and their relationships to soil nutrient concentrations and plant growth parameters

Application to land of large quantities of waste materials from concentrated animal production, without causing environmental pollution, presents a major challenge to agriculture in the 21st century. Effects of land-applied animal wastes on chemical contents of soil are well documented, but less is understood of their effects on microbial populations in soil. This study was undertaken to evaluate effects of commercial application of poultry litter (PL), as a fertilizer, on soil fungal population levels and components on cotton farms in Mississippi, and to determine relationships of fungal population levels to soil nutrient contents and cotton growth and yield. On each of two farms, soil fungal population levels were estimated by dilution plating from samples of soil collected at two sampling times during 2 years from replicated plots of four fertilization treatments: 0 fertilizer, conventional mineral fertilizer (CF), low PL, and high PL. Soil fungal population levels differed significantly (P = 0.05) according to years or seasons and fertilization treatments on both farms. Population levels often were higher in soils amended with low or high PL, or with CF, than in unfertilized controls. On one farm where PL was tilled into soil, fungal population levels increased significantly during the course of the experiment in PL and CF treatments, but not in unfertilized controls, as determined by linear regression. No such increases were observed on the second farm where PL was applied no-till. Population levels of Fusarium semitectum and Penicillium purpurogenum were significantly higher in PL-treated soils than in unfertilized controls in 1 or 2 of 4 sampling events at both farms, while levels of four other species or groups of fungi usually did not differ. Fungal population levels were significantly correlated (P = 0.05) with N concentrations of soils in 1–4 sampling events on each farm and less frequently correlated with concentrations of nine other elements. In 4 of 24 instances, soil fungal population levels were significantly correlated with leaf area index, chlorophyll content, or yield of cotton, and correlation coefficients with these plant parameters were always positive. Major conclusions derived from this study are (1) no deleterious effects on population levels of total or select soil fungi were observed with use of PL as a fertilizer for commercial cotton production; and (2) soil fungal population levels may increase over time in association with greater fertility and plant growth that is induced by both mineral fertilizer and PL applications.     

Productivity of different cow genetic groups in dual-purpose cattle production systems in south-eastern Mexico

The objective was to evaluate the effect of cow genetic group, nutritional level and their interaction on some economically important traits of dual-purpose herds managed under field conditions. Nine herds were monitored during a production cycle in Yucatan, Mexico. Herds were grouped into four nutritional levels (NL) based on the metabolizable energy (ME) apparently available on pasture, nutritional management, and milk production. Cows were classified into three genetic groups (GG): low (≤25%), middle (25–75%) and high (≥75%) graded for Bos taurus inheritance. Total milk sold (TMS), days in milk (DIM), TMS adjusted to DIM within each NL (TMSA), body condition score (BCS) at calving, changes of BCS during lactation (CBCS), calf weaning weight (WW), age at weaning (AW), kg of calf weaned per cow (KWC) and calf mortality were studied. The statistical model included the fixed effects of NL, GG, month of calving (MC), parity number (PN) and BCS at calving and GG × NL interaction. The effects of NL, GG, MC, PN and GG × NL were significant (p < 0.05) for TMS, KWC. As expected, TMS increased with NL from 562.4 ± 106 kg for NL1 to 2366.3 ± 100.1 kg for NL4. KWC was greatest for NL2 (138.6 kg) followed by NL1 (135 kg); the lowest KWC corresponded to NL4 (96.0 kg) (p < 0.05). TMS values for the middle (1727 ± 94.7 kg) and the high graded GG (1603.5 ± 83.5 kg) were twice those for the low graded GG cows (828.5 ± 95 kg) (p < 0.05). KWC was also higher for the middle graded group (152.8 kg) than for the low or (104 kg) or the high graded GG (118 kg) (p < 0.05). With better nutrition cows of all GG improved their milk performance but not the calf traits. CBCS was negative for all GG. The highest BCS lost was for cows in NL1 and NL2 and for cows in the high graded GG (p < 0.05).     

Vegetative and reproductive dry weight inhibition in nitrogen‐ and phosphorus‐deficient Pima cotton 1

Whether the extent of dry weight inhibition by nitrogen (N) or phosphorus (P) deficiencies on different plant parts is the same and whether imposing moderate N and P deficiencies selectively suppress undesirable vegetative growth has not been studied in Pima cotton (Gossypium barbadense L.). The purpose of this study was to determine the extent to which dry matter accumulation in leaves, stems, and reproductive structures is inhibited by N and P deficiencies in Pima cotton. The study was conducted in 1991 and 1992 in a Uvalde silty clay loam soil (fine‐silty, mixed, hyperthermic Aridic Calciustolls). The treatments included applied rates of 0, 67, 135, 202, and 269 kg N ha^‐1 in a factorial combination with 0, 15, 29, and 44 kg P ha^‐1. Nitrogen deficiency (0 kg N ha^‐1) significantly (P≤0.05) reduced leaf (LDW) and stem (SDW) dry weights in both years and reproductive dry weight (RDW) in 1992. Nitrogen deficiency suppressed dry weight accumulation in leaves to a greater extent than in stems. Relative to 269 kg N ha^‐1, the 0 kg N ha^‐1 treatment resulted in a maximum LDW reduction of 62% at 144 DAP (days after planting) in 1991 and 36% at 121 DAP in 1992, compared with a corresponding SDW reduction of only 39% in 1991 and 25% in 1992. Dry weight accumulation in reproductive parts was the least affected by N deficiency. The decline in LDW associated with senescence and defoliation began earlier in treatments that received 0 or 67 kg N ha^‐1 than treatments that received ≥135 kg N ha^‐1. Phosphorus affected LDW and SDW in 1991, but its differential effect on LDW, SDW, and RDW was much smaller than that of N. Imposing a moderate level of N deficiency, not P deficiency, may be an effective Pima cotton management strategy to selectively suppress undesirable vegetative growth and enhance maturity.     

Macronutrient concentration in plant parts of cotton fertilized with broiler litter in a marginal upland soil

Effectiveness of surface-applied unincorporated broiler litter as a fertilizer relative to conventional inorganic fertilizers under no-till or conventional-till cotton (Gossypium hirsutum L.) production systems in the upland soils of the southern and southeastern USA is not well documented. The objectives of this research were to (1) test if broiler litter improves plant macronutrient (N, P, K, and Mg) nutrition of cotton above that of cotton fertilized with conventional inorganic fertilizers and (2) determine if lack of incorporating litter into the soil reduces macronutrient concentration in cotton plant parts in an upland soil considered marginal for cotton. Six treatments consisting of an unfertilized control, a fertilized standard (STD), two litter-only, and two litter plus inorganic N as urea–ammonium nitrate solution (UAN) were tested in two adjacent fields, one under no-till (NT) and the other under conventional-till (CT) systems. Litter alone, UAN, or a combination of litter plus UAN were applied to supply 101 kg ha⁻¹ plant available N assuming nearly all of the UAN-N and 50% of the total litter N becomes plant available during the cotton growing season. Concentration of N, P, K, and Mg were measured in leaves, stems, and reproductive parts on three or four dates between early flowering and maturity. Cotton fertilized with the litter-only treatments always had less N concentration but greater P and K concentration in leaves, stems, and reproductive parts than cotton that received the STD treatment. Leaf and stem Mg concentration seems to depend on the N concentration in these plant parts. Lack of incorporating litter into the soil reduced N concentration in nearly all plant parts at all growth stages, suggesting some amount of the litter-derived N is lost due to lack of incorporation. Lack of incorporation also reduced leaf and stem Mg concentration, which seemed to be due to its reducing effect on N concentration. Unlike N and Mg, lack of incorporation did not consistently affect concentrations of P and K in all plant parts. Regardless of the incorporation treatment, fertilization with the litter-only treatments increased tissue P and K concentration and supported lint yield exceeding that of the STD without increasing tissue N concentration.     

Reproductive Abscission and Yield of Irrigated and Drought Stressed Cowpea

Two experiments were conducted under field conditions to evaluate reproductive abscission, seed yield and yield components of three cowpea [Vigna unguiculata (L.) Walp.] genotypes. In the first experiment, level of abscission and yield of two cultivars, California Blackeye Pea No. 5 (CA-5) and Speckle Purple Hull (SPH), and one experimental line (AZ-54) were studied. In the second experiment, effect of drought stress on abscission at three nodal positions, seed yield, and yield components of CA-5 were studied. Abscission in both experiments was determined by counting scars left by dropprd reproductive structures including floral buds, open flowers, and immature pods. Abscission of CA-5 and AZ-54 in the first experiment ranged between 68 and 76 % while that of SPH ranged between 86 and 89 %. CA-5 and AZ-54 retained two to three pods per peduncle, and SPH retained only one mature pod per peduncle. Average seed yields of SPH and AZ-54, respectively, were 45 and 50 % of CA-5. Drought stress in the second experiment did not affect production of floral buds Peduncle^?1 (average of 10) but significantly increased percent reproductive abscission and decreased pod retention of CA-5. Abscission in the bottom two-third nodes increased from 82 % in well-irrigated plants to 93 % in non-irrigated plants. This increase in abscission corresponded to nearly 60 % reduction in pod retention. The number of pods per peduncle in the bottom two-third nodes decreased from 1.9 in well-irrigated plants to only. 77 in non-irrigated plants. The increase in abscission and decrease in pod retention with increasing intensity of drought was greatest in the bottom one-third nodes. Drought stress did not affect abscission and pod retention in the top one-third nodes. Stress also decreased peduncles plant^?1, seeds pod^?1, and dry matter and seed yield plant^?1 but did not affect seed weight and harvest index. The decrease in seed yield was largely due to reductions in pods plant^?1 and seeds pod^?1. The reduction in the number of pods and, therefore, seed yield due to stress was because of reductions in the number of peduncles plant^?1 and increases in reproductive abscission. It is concluded external conditions that increase abscission beyond that of normal occurrence affect seed yield adversely.     

Wheat Cultivars Adapted to Post-Heading High Temperature Stress

The existence of genetic variation in wheat for tolerance to high temperature stress has been reported but cultivars released for a particular production system often are not characterized. The objective of this study was to identify and describe the characteristics of wheat cultivars adapted to production systems with risks of high temperature during the post‐heading period. Fifteen diverse wheat cultivars and one unreleased genotype were evaluated at the Texas A&M University Agricultural Research and Extension Center, Uvalde, TX, during two seasons characterized by daily maximum temperatures as high as 36 °C. Measurements during both seasons included days to heading, days to physiological maturity and grain yield. Large and significant (P < 0.05) grain yield differences were measured among cultivars within each season. Yield varied between 2979 and 4671 kg ha^?1 in the first season and between 1916 and 5200 kg ha^?1 in the second season. Late planting in the second season delayed heading date resulting in the post‐heading period to coincide with periods of high temperatures. Cultivars that headed early, in general, yielded better than cultivars that headed later within each season with yield reduction of 35.3 kg ha^?1 in the first season and 91.0 kg ha^?1 in the second season for every 1 day delay in heading after mid‐March. Early‐heading cultivars outperformed later‐heading cultivars because of two distinct advantages: the early‐heading cultivars had longer post‐heading and, therefore, longer grain filling period than the later‐heading cultivars. In addition, early‐heading cultivars completed a greater fraction of the grain filling earlier in the season when air temperatures were lower and generally more favourable. The advantage of earlier‐heading cultivars was also manifested in the amount of green leaves retained to anthesis. Earlier‐heading cultivars produced fewer total leaves per tiller but retained more green leaves and lost fewer leaves to senescence at anthesis than later‐heading cultivars. The results suggest that early heading is an important and effective single trait defining wheat cultivars adapted to production systems prone to high temperature stress during the post‐heading period.     

Soil aggregation and water holding capacity of soil amended with agro-industrial byproducts and poultry litter

Journal of Soils and Sediments - Soil organic matter (SOM) addition has been shown to be effective for improving physicochemical and hydrological properties, but its effectiveness may be improved...     

Nitrogen uptake and transfer in broad bean and garlic strip intercropping systems

Utilization and transfer of nitrogen(N)in a strip intercropping system of garlic(Allium sativum L.)and broad bean(Vicia faba L.)have been investigated rarely.The objectives of this study were to quantify N uptake and utilization by intercropped broad bean and garlic and determine the magnitude of N transfer from broad bean to garlic.Field and pot trials were carried out in the Erhai Lake Basin in China using ~(15)N tracer applied to the soil or injected into broad bean plants.Strip intercropping of garlic and broad bean increased N absorption(47.2%)compared with sole crop broad bean(31.9%)or sole crop garlic(40.7%)and reduced soil residual N.Nearly 15%of ~(15)N injected into petioles of broad bean intercropped with garlic was recovered in garlic at harvest,suggesting that N could be transferred from broad bean to strip intercropped garlic.The findings provide a basis for evaluating legumes’role in optimizing N fertilization when intercropped with non-legumes.