Potassium losses in runoff from cotton production fields

Tillage and cover cropping are known to affect soil water dynamics and crop evapotranspiration (ET), and consequently, water footprint (WF) of crop production and economic return. In this study, two tillage practices (conventional tillage [CT] and no‐tillage [NT]) and cover crop (CC) treatments (Austrian winter pea [ Pisum sativum ] CC and no‐CC [NC]) were investigated to quantify soil water balance, ET, and WF of yield and revenue for cotton ( Gossypium hirsutum ) and sorghum ( Sorghum bicolor ) production. Soil volumetric water content was measured from 0‐ to 120‐cm depth from May to October in 2020 and 2021. Runoff, deep percolation, and ET were modeled using the root zone water quality model (RZWQM2), and WF was determined as m 3 of water consumed per kg of yield or unit revenue. The RZWQM2 performance was acceptable, validated by low residual errors. Pooled across years, CT treatments depleted soil water storage by 9% and 7% over the season in cotton and sorghum, respectively, which was 6% and 7% for NT. No‐till reduced the runoff by 31% over CT when averaged across years and cash crops. The NTCC (no‐tillage, cover crop) minimized ET, compared to NTNC (no‐tillage, no cover crop) and CT treatments, particularly in sorghum. Tillage increased the WF of yield and revenue for cotton by 7% and 6% over NT treatments, respectively. In sorghum, neither tillage nor cover cropping altered the WF outcomes. Overall, cover cropping and conservation tillage could be used to complement each other to minimize the WF of cotton and sorghum production in the humid Lower Mississippi River Basin.

ABSTRACTWinter cereals are often used as cover crops before planting cotton (Gossypium hirsutum L.). Black oat (Avena strigosa Schreb.) is the predominate cereal cover crop for cash crops in southern Brazil and Paraguay, but limited information is available on the suitability of black oat as a cover crop in the southeastern USA. The objectives of this study were to compare black oat with adapted winter cereals for this region and to determine the effect of cereal residue species and amount on cotton growth, N status, and lint yield. In a greenhouse study in which black oat and rye (Secale cereale L.) residues were mixed with soil, tap root elongation of both cotton and radish (Raphanus sativa L.) was inhibited more by black oat residue than by rye residue. In a field experiment on a Goldsboro loamy sand (fine‐loamy, siliceous, thermic Aquic Kandiudult), cotton was grown in 1995 and 1996 following black oat, oat (Avena sativa L.), rye, and wheat (Triticum aestivum L.) that were planted at three different times (October, November, and December). All four winter cereals had similar biomass production at each planting date in 1995. In 1996, rye was the only species not visibly damaged by a low temperature of −12.2°C that occurred during the winter. Black oat biomass was comparable to wheat in all planting dates but averaged 60% less than rye over all three planting dates and was 37% less than oat in the October planting date in that year. Black oat tended to have a higher N concentration than the other cereal species. Cotton plant density was lowest following black oat and rye. Cotton growth, leaf blade N, and petiole NO3‐N were more dependent on residue amount than on residue species. Cotton lint yield following black oat was 120 kg ha−1 higher than lint yield of cotton following rye. Cotton following black oat, wheat, and oat had similar lint yield. Black oat may be a promising cover crop for the southeastern USA, but evaluations of other cultivars and/or improvement programs to improve cold hardiness are needed to improve the utility of this species.

Intensive cotton farming technologies in China: Achievements, challenges and countermeasures

Inadequate and less vigorous crop stand is a constraint to adoption of conservation tillage in cotton (Gossypium hirsutum L.) production. We evaluated the effects of tillage (conventional till, mulch‐till, no‐till), cropping system (cotton–winter fallow, cotton–winter rye, Secale cereale L.), and N source and rate (ammonium nitrate and poultry litter; 0, 100, and 200 kg N ha−1) on cotton seedling emergence on a Decatur silt loam soil (Typic Paleudults) in northern Alabama, from 1996 to 1998. Cotton seedling counts under no‐till were 40 to 150% greater than those under conventional till at 1 and 2 d during seedling emergence. Cotton–winter rye cropping system had 14 to 50% greater seedling counts than cotton–winter fallow cropping during the first 4 d of emergence in 1998. Poultry litter source of N gave 17 to 50% greater cotton seedling counts than ammonium nitrate during the first 4 d of emergence in 1998. In all these cases, the differences progressively narrowed down by the 4th day of seedling emergence. Cotton seedling counts were significantly correlated to cotton growth parameters and lint yield, especially in the drier year (1998). These results were attributed to soil moisture conservation during seedling emergence. Our results show that conservation tillage improved cotton germination, emergence, dry matter, and lint yield. Therefore, no‐till with winter rye cover cropping and poultry litter can be used for achieving early cotton seedling emergence and growth in the U.S. cotton belt where dryland cotton production systems are on the increase and safe disposal of poultry litter is becoming an environmental problem.

Cover crop effect on soil carbon fractions under conservation tillage cotton

Introducing integrated crop‐livestock systems into row crop production promotes income diversification and potential soil health benefits through cover crop grazing on degraded soils of the southeastern United States, but effects of these practices on crop yields and soil health in Coastal Plain soils are not well established. A 4‐year study was performed to evaluate the effects of grazing a multi‐species winter cover crop on soil health and crop yields under mid‐February, mid‐March, and mid‐April cattle removal dates and a non‐grazed control within an annual cotton (Gossypium hirsutum L.) and peanut crop rotation (Arachis hypogaea L.). Chemical soil health indicators (soil organic carbon and permanganate oxidizable carbon), physical soil health indicators (water‐stable aggregates and penetration resistance), biological soil health indicators (microbial biomass carbon, soil respiration, and arbuscular mycorrhizal fungi colonization), crop yield, and cover crop biomass were evaluated. Cover crop biomass at termination was reduced by 3660, 5250, and 5610 kg ha−1 for the mid‐February, mid‐March, and mid‐April cattle removal treatments compared to the non‐grazed control. No grazing treatment effects were observed for biological soil properties. Soil organic carbon was higher in the non‐grazed treatment than the mid‐April grazing treatment across 0‐ to 30‐cm depth. Penetration resistance across 0‐ to 50‐cm depth and water‐stable aggregates at the 0‐ to 30‐cm depth were both negatively impacted by increased grazing period lengths. Results from this study suggest that longer cover crop grazing periods have little effect on biological and chemical soil health indicators in the short term but can negatively impact some physical soil health indicators.

Grazing cover crops may increase land‐use efficiency while promoting sustainability. We investigated how grazing intensity affects cover crop litter quantity, quality, decomposition, and cotton (Gossypium hirsutum L.) N uptake. Cover crops were a mixture of rye (Secale cereale L.) and oat (Avena sativa L.) managed as follows: no grazing +34 kg N ha−1 (NG34), no grazing +90 kg N ha−1 (NG90), heavy grazing (HG), moderate grazing (MG), and light grazing (LG). Grazed treatments received 90 kg N ha−1. After cover crop termination, above‐ and belowground litter was collected and incubated in situ for 0, 4, 8, 16, 32, 64, and 128 days, with cotton plants sampled on the same days to estimate N recovery and synchrony between N release from litter and uptake by cotton. By Day 128, only 13% of initial NG34 aboveground biomass had disappeared, whereas 42% of HG disappeared. Nitrogen retained in aboveground litter of HG was less than NG90 (27 vs. 60 kg N ha−1), and aboveground final N stock (at Day 128) of HG was less than NG90 and LG (16, 47, and 41 kg N ha−1, respectively). Belowground litter contributed 98 kg N ha−1 versus 46 for aboveground. Belowground N disappearance from litter bags was greater from NG90 than NG34 (39 vs. 21 kg N ha−1). Cotton N uptake by Day 128 was similar across treatments (191 kg N ha−1). Grazing cover crops impact aboveground litter quantity, quality, and decomposition rates, and belowground litter plays an important role on the N cycling.

The short‐season concept (early defoliation and early harvest) offers, perhaps, the greatest potential for increasing the efficiency of cotton (Gossypium hirsutum L.) production and for minimizing insect control requirements in the Lower Rio Grande Valley of Texas. Early defoliation also allows harvesting during the most optimum period in relation to expected rainfall.The fruiting, earliness, yield, and fiber quality of three determinate cultivars of early‐maturing cotton were compared with those of a standard nondeterminate cultivar to determine the potential of these cultivars for increasing cotton production efficiency in the Lower Rio Grande Valley. The determinate cultivars, ‘Paymaster 266,’ ‘Paymaster Dwarf,’ and ‘Acco 1764,’ produced their first blooms 3 to 7 days earlier and developed a very high rate of bloom production shortly after the first blooms, as compared with the standard cultivar, ‘TPSA 110.’ The determinate cultivars set fruit over a relatively short time, making early defoliation and harvest feasible with comparable yield and only a slight reduction in fiber quality.

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

Tillage and cover crops affect soil biological, chemical and physical properties that control the fate of herbicides in soil. Effects of conventional tillage (CT) and no tillage (NT) and either native winter annual vegetation, hairy vetch (Vicia villosa) or wheat (Triticum aestivum) on degradation of pendimethalin [N‐(1‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine] were investigated. Effect of pendimethalin sorption on residues of these cover crops on subsequent washoff by simulated rain was also examined. Surface (0 to 3 cm) Gigger soil (fine‐silty, mixed thermic Typic Fragiudalfs) from triplicate plots of each tillage by cover crop combination under long‐term cotton (Gossypium hirsutum) were fortified with pendimethalin (10 nmole g− 1), incubated (25 ± 1°C) for 7, 21, 42, and 63 d, extracted and analyzed for pendimethalin by HPLC. Degradation was generally faster in NT than CT soil. Within tillage treatments, degradation was faster under native vegetation and wheat cover than under vetch. First‐order degradation, half‐lives ranged from 47 d (CT vetch) to 17 d (NT native), however, the data were better described by a nonlinear degradation model. Sorption KDs (= µmole kg− 1/µmole L− 1) for pendimethalin retention on residues were determined in a batch study (1:500, residue:0.80 µM pendimethalin, shaken for 24 h, and analyzed by HPLC). Measured KDs were large, ranging from ~3000 L kg− 1 for native vegetation and wheat to ∼ 6000 L kg− 1 for vetch. When pendimethalin was spray‐applied at 1.12 and 2.24 kg ha− 1 to triplicate 4‐g samples of residues and desorbed by three 2‐cm simulated rains, < 1% was recovered. Low recovery was consistent with high sorption and predicted using KDs but indicates that benefits of pendimethalin for weed control in NT systems with dense cover crop residues warrants further investigation.

Palmer amaranth (Amaranthus palmeri S. Watson) is the most problematic weed of cotton (Gossypium hirsutum L.)-cropping systems in the U.S. Southeast. Heavy reliance on herbicides has selected for resistance to multiple herbicide mechanisms of action. Effective management of this weed may require the integration of cultural practices that limit germination, establishment, and growth. Cover crops have been promoted as a cultural practice that targets these processes. We conducted a 2-yr study in Georgia, USA, to measure the effects of two annual cover crops (cereal rye [Secale cereale L.] and crimson clover [Trifolium incarnatum L.]), a perennial living mulch (‘Durana®’ white clover [Trifolium repens L.]), and a bare ground control on A. palmeri population dynamics. The study was conducted in the absence of herbicides. Growth stages were integrated into a basic demographic model to evaluate differences in population trajectories. Cereal rye and living mulch treatments suppressed weed seedling recruitment (seedlings seed−1) 19.2 and 13 times and 12 and 25 times more than the bare ground control, respectively. Low recruitment was correlated positively with low light transmission (photosynthetic active radiation: above canopy photosynthetically active radiation [PAR]/below cover crop PAR) at the soil surface. Low recruitment rates were also negatively correlated with high survival rates. Greater survival rates and reduced adult plant densities resulted in greater biomass (g plant−1) and fecundity (seeds plant−1) in cereal rye and living mulch treatments in both years. The annual rate of population change (seeds seed−1) was equivalent across all treatments in the first year but was greater in the living mulch treatment in the second year. Our results highlight the potential of annual cover crops and living mulches for suppressing A. palmeri seedling recruitment and would be valuable tools as part of an integrated weed management strategy.

Field experiments were conducted consecutively for 2 years at Coimbatore between 2002-03 and 2003-04 crop seasons during winter (August - February). Cotton (Gossypium hirsutum L.) followed by summer (March - May), maize (Zea mays L.) crops using different thickness black polyethylene mulch film of 30, 50, 75 and 100 micron were evaluated against conventionally planted (no mulch) cotton - maize cropping system for moisture conservation and enhanced crop production efficiency. Higher uptake of nutrients due to higher temperature coupled with higher available soil moisture caused significant increase in root cation exchange capacity, nutrient uptake, dry matter accumulation and partitioning of assimilates under polyethylene mulching with an average yield enhancement of 1.83 to 1.90 fold in cotton and 1.95 to 2.10 fold in maize crops besides saving water. The water requirement of mulched cotton was 58.63 ha-cm whereas conventionally grown cotton was 84.19 ha-cm. The water use efficiency of mulched cotton was 43.2 kglha-cm as against 16.6 kglha-cm for conventionally planted no mulch cotton crop. The poly-mulched cotton-maize system recorded the highest net return (Rs 74,1781ha) and benefit cost ratio (1.68) as against the conventional system (Rs 29,863 and 1.04).

The experiment was conducted during 2019 and 2020 at Regional Research Station (Punjab Agricultural University, Ludhiana, Punjab), Faridkot, Punjab to evaluate the impact of different drip irrigation and fertigation regimes on Bt cotton (Gossypium hirsutum L.) (cv. RCH 773 BGII). The experiment was conducted in a randomized complete block design (RCBD) comprised of 3 drip irrigation levels (60%, 80%, and 100% of ETc); 2 fertigation doses (75% and 100% of recommended nitrogen dose), along with two extra control treatments (surface flood irrigation with 105 kg N/ha and subsurface flood irrigation with 112.5 kg N/ha). Results revealed that surface drip irrigation significantly reduced water usage by 13.9–32.3% as compared to conventional surface flood irrigation, while seed cotton yield increased by 18.2–25.2%. Notably, subsurface drip fertigation (SSDF) (100% recommended level of nitrogen applied at 80% ETc) exhibited the potential to conserve about 8.9–25.7% of total water applied, besides boosting crop yield by 37.2%. In conclusion, this study elucidated better crop and water productivity with subsurface drip followed by surface drip irrigation as compared to traditional surface flood irrigation and manual fertilizer application. Therefore, adoption of drip irrigation systems for water and nitrogen application needs to be advocated for sustainable cotton cultivation.

Past agricultural management practices have contributed to the loss of soil organic carbon (SOC) and emission of greenhouse gases (e.g., carbon dioxide and nitrous oxide). Fortunately, however, conservation-oriented agricultural management systems can be, and have been, developed to sequester SOC, improve soil quality, and increase crop productivity. Our objectives were to (i) review literature related to SOC sequestration in cotton (Gossypium hirsutum L.) production systems, (ii) recommend best management practices to sequester SOC, and (iii) outline the current political scenario and future probabilities for cotton producers to benefit from SOC sequestration. From a review of 20 studies in the region, SOC increased with no tillage compared with conventional tillage by 0.48 +/- 0.56 Mg C ha(-1) yr(-1) (H(0): no change, p < 0.001). More diverse rotations of cotton with high-residue-producing crops such as corn (Zea mays L.) and small grains would sequester greater quantities of SOC than continuous cotton. No-tillage cropping with a cover crop sequestered 0.67 +/- 0.63 Mg C ha(-1) yr(-1), while that of no-tillage cropping without a cover crop sequestered 0.34 +/- 47 Mg C ha(-1) yr(-1) (mean comparison, p = 0.04). Current government incentive programs recommend agricultural practices that would contribute to SOC sequestration. Participation in the Conservation Security Program could lead to government payments of up to Dollars 20 ha(-1). Current open-market trading of C credits would appear to yield less than Dollars 3 ha(-1), although prices would greatly increase should a government policy to limit greenhouse gas emissions be mandated.

Inheritance of 81A genetic male-sterility with ‘virescent’ marker character and its cytology in Upland cotton (Gossypium hirsutum L.) are presented. The chromosome number of 81A is normal, 2n = 52, and pollen abortion occurs mainly in the late uninuclear stage. Male-sterility and virescence in 81A are controlled by one pair of recessive gene. Because male sterility and virescence showed no recombination, pleiotropy is assumed. However, very close linkage could not be ruled out. Allelic tests indicated that virescence observed in 81A is non-allelic to all virescence genes identified earlier in Upland cotton and its male-sterility is non-allelic to msc1, msc2 and msc3 discovered in P.R. China. It is proposed that 81A male-sterile gene symbol be tentatively named to msc7. The development of 81A genetic male-sterile line associated with virescence trait could raise considerably the efficiency of the hybrid seed production in cotton.