Cotton Rotation Research Articles

Steers Grazing a Rye Cover Crop Influence Growth of Rye and No‐Till Cotton

Small grain cover crops offer grazing opportunities but effects on following row crops are not well understood. From 1999 through 2008, stocker steers (Bos taurus) grazed small grains in a two‐paddock crop rotation of rye (Secale cereale L.), cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.), fallow, and rye. Treatments in 2005, 2007, and 2008 included (i) zero‐grazed rye from 1999; (ii) ungrazed rye in the current year only; (iii) always grazed rye; and (iv) in 2007 and 2008, monoculture cotton (since 1999) with no cover crop. The experiment, on a Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustolls), was a randomized complete block design with three blocks. Ungrazed rye was mechanically harvested before planting cotton. Rye excluded from grazing in 1 yr only (Treatment 2) was taller (P < 0.05) and produced more forage mass than zero‐grazed rye (Treatment 1), likely due to higher rye tiller numbers, weight, and basal cover. Cotton planted into grazed rye had more plants m–1 row and was taller until July (P < 0.05), and in 2005 had greater (P < 0.05) lint and seed yield than where grazing was excluded. Continuous cotton with no cover crop (Treatment 4) was shorter (P < 0.01) than cotton grown with a cover crop regardless of grazing. Known allelopathic chemicals were detected in rye and soil where rye grew and appeared to be influenced by grazing. Increased growth and productivity of rye and cotton where grazing occurred may be related to suppressive effects of grazing on allelopathy.

Wet years and farmers’ practices may offset the benefits of residue retention on runoff and yield in cotton fields in the Sudan–Sahelian zone

Cotton (Gossypium hirsutum L.) is sensitive to water shortage during its establishment phase. In the Sudan–Sahelian zone, a significant part of rainfall events can be lost through runoff, particularly as the rainy season begins. Using residues from previous crops as soil cover is expected to reduce runoff and thus improve water availability to young cotton plants. To test this hypothesis, we set up a trial in Sikasso, Southern Mali, with a two-year rotation of cotton and sorghum (Sorghum bicolor L.). The conventional cropping system (CS) was compared with two no-tillage, mulch-based cropping systems, where cotton was grown on straw residues of a sorghum crop (DMC1) or sorghum/brachiaria (Brachiaria ruziziensis) intercropping (DMC2). Soils in this region are classified as ferruginous types with hydromorphic characteristics at depths below 0.7m (Plinthic Haplustalfs). Measurements included runoff, soil water content, biomass, cotton yield, and soil surface status (i.e. covered, open with visible macropores, or closed with no visible macropores). On DMC systems, the amounts of residues from the preceding crop kept on the soil surface at the beginning of the cotton cycle ranged from 4.4 to 9.3×103kgha−1 of dry matter, depending on the year and preceding crop. The soil surface status was more open under DMC1 and DMC2 (38 and 62%, respectively) than under CS (30%). Crop residues reduced runoff at the beginning of the rainy season in both years (−26 and −56mm between CS and DMC2 in 2006 and 2007, respectively) and increased soil water availability for cotton (+26mm and +50mm, respectively). This gain in soil water did not result in higher cotton yields, probably because 2006 and 2007 rainfall amounts were unusually high, with a low gap between water supply and cotton requirements. Row ridges made perpendicular to the slope and after sowing in CS, created an effective obstacle to runoff and increased soil water content. The effects of crop residues on rainwater infiltration accumulated over the entire growing season were minimal. In conclusion, during wetter periods, the potential benefit of DMC systems on water balance and cotton yield in these types of soil may be low when compared with conventional systems if ridging done perpendicular to the slope is added.

Conservation agriculture in eastern and southern provinces of Zambia: Long-term effects on soil quality and maize productivity

Sustainable and resilient cropping systems are required in southern Africa to arrest declining soil fertility and offset the future negative effects of climate change. Conservation agriculture (CA) has been proposed as a potential system for improving soil quality and providing stable yields through minimum soil disturbance, surface crop residue retention (mulching) and crop rotations or associations. However, concerns have been raised about the lack of evidence of the benefits of CA for small-scale farmers in southern Africa. This research was carried out in two communities and one on-station site in Zambia to provide more scientific evidence about the effects of CA on soil quality, infiltration, soil moisture and crop performance. Results from Kayowozi showed that maize yields in a direct seeded CA treatment, using cowpea seeded with a dibble stick in full rotation, increased by up to 78% after four cropping seasons in comparison to a conventional control using a ridge and furrow system. At Malende, maize yields for animal traction rip-line seeded and direct seeded plots were, on average, 75% and 91% higher than a conventionally tilled control plot after six cropping seasons. Detailed studies undertaken at the Monze Farmer Training Centre revealed that CA treatments, especially that using cotton in rotation, increased water infiltration and soil moisture. In some years, infiltration was five times higher on CA fields than on those using conventional tillage. Carbon increases were only found at the on-station long-term trial, where, over time, CA plots outperformed conventional practice leading to an overall increase of 12% carbon in the first 30cm, compared with decreases of 15% in the conventional control. Comparative analyses between the on-farm and on-station trials point to a lack of adequate mulching, which might be the reason for lower carbon at the on-farm sites. We conclude that the effects of CA can build up on different soil types in most systems, but that scaling up and out requires the whole community to be targeted, rather than relying on individual farmers to overcome constraints related to the set-up in rural communities.

Use of Winter Legumes as Banker Plants for Beneficial Insect Species in a Sorghum and Cotton Rotation System

Abstract Use of novel crops for bio-fuel production requires evaluating the potential for sound ecological and economical implementation in a particular region. We examined the pest and generalist beneficial insect species associated with various winter cover crops (including narrowleaf lupin, white vetch, Austrian winter pea, crimson clover, faba bean, and rye) as sources of colonists in 2 subsequent summer crops, sorghum and cotton. Sorghum is a potential cellulosic bio-fuel crop and cotton is commonly grown in the region and could be a viable low-input rotation for biofuel sorghum. Insects were sampled weekly over 3 ys in winter cover plots beginning in early spring and in the later planted crop plots beginning at the 15 cm height stage of the crops and continuing for 3 - 6 wks. Of the predators, coccinellids (Coleoptera: Coccinellidae) dominated and were consistently abundant in vetch, faba and lupin, as was the pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae) and the aphid parasitoid, Lys...

Soil management and traffic effects on infiltration of irrigation water applied using sprinklers

Zero tillage and controlled traffic have been proposed as means for more productive and sustainable irrigated farming. Both practices affect soil infiltration characteristics and, therefore, should have effects on sprinkler irrigation performance. This study compared water infiltration and runoff in three sprinkler irrigation tests performed on an alluvial loam soil at different times during a maize (Zea mays L.)–cotton (Gossypium hirstium L.) rotation under two soil managements: permanent beds with crop residue retention (PB: planting beds maintained unaltered from year to year) and conventional beds with residues incorporated with tillage (CB: disc and chisel ploughing followed by rotavator pass and bed forming every year). Traffic was controlled and two types of furrows were distinguished in both tillage systems: with (+T) and without (−T) wheel traffic. The irrigation tests were performed on maize at full cover, on bare soil just before cotton sowing and on cotton with 50% ground cover. Infiltration and runoff were affected notably by both traffic and soil management. The soil under PB infiltrated more water than under CB, and −T furrows more than +T furrows. Considering the combined treatments, −T furrows in the CB system infiltrated more water than +T furrows in the PB system. A sprinkler irrigation model for simulating water application and soil infiltration and runoff was formulated. The model was used to analyse irrigation performance under infiltration characteristic of the CB and PB systems in trafficked and non-trafficked furrows. Five irrigation performance indicators were used to assess the various combinations of tillage and traffic: Wilkox–Swailes coefficient of uniformity; application efficiency; deep percolation ratio; tail water ratio; and adequacy. The model was used to develop operation diagrams and provided guidelines for making irrigation decisions in the new controlled traffic/permanent bed system and in a standard conventional system.

Dynamics of soil organic carbon in an innovative irrigated permanent bed system on sloping land in southern Spain

Irrigated spring cropping systems on sloping soils require conservation agriculture (CA) to minimise soil erosion. In southern Spain, management of residues in the commonly-practiced maize–cotton rotation is a major hurdle against adoption of CA. Recently, a minimal-cultivation, irrigated permanent bed system has been developed in which, two weeks before sowing, maize or cotton residues are relocated from the seed rows on the top of beds into the furrows. This allows solar heating of the beds which accelerates seedling emergence. This paper presents the effects that the introduction of this system had on soil properties along a variably-sloping landscape in which six homogeneous zones were identified. It also discusses the system's potential for carbon sequestration and shows that a similar quantity of carbon is stored after 4 years under irrigated permanent beds to that after 11–21 years in rainfed no-tillage systems. The relocation of residues resulted on average in lower soil organic carbon concentration (SOCc) in the beds than in the furrows (1.40 and 1.51% respectively in the top 5 cm of soil). Under this system SOCc also varied among the landscape zones particularly in the top layers. SOCc was highest in the most eroded shoulder-backslope zone (Z2) though soil organic carbon storage (SOCs) there was the lowest because of the zone's high >2-mm soil fraction. The SOCs (0–30 cm) global average during the study was 35.2 Mg C ha −1 and ranged from 22.4 Mg C ha −1 in the shoulder Z2 zone to 41.4 Mg C ha −1 in the Z5 footslope zone. When compared to conventionally-managed fields nearby, following this management system appeared to improve soil characteristics significantly and protect against soil erosion.

Improved growth and nutrient status of an oat cover crop in sod-based versus conventional peanut-cotton rotations

Nitrogen (N) leaching from agricultural soils is a major concern in the southeastern USA. A winter cover crop following the summer crop rotation is essential for controlling N leaching and soil run-off, thereby improving sustainable development. Rotation of peanut (Arachis hypogea L.) and cotton (Gossypium hirsutum L.) with bahiagrass (Paspalum notatum) (i.e. sod-based rotation) can greatly improve soil health and increase crop yields and profitability. In the sod-based rotation, the winter cover crop is an important component. The objective of this study was to determine effects of summer crops, cotton and peanut, on growth and physiology of a subsequent oat (Avena sativa L.) cover crop in both a conventional (Peanut-Cotton-Cotton) and sod-based (Bahiagrass-Bahiagrass-Peanut-Cotton) rotations. Two rotations with an oat cover crop were established in 2000. In the 2006-07 and 2007-08 growing seasons, oat plant height, leaf chlorophyll and sap NO3-N concentrations, shoot biomass, and N uptake were determined. Our results showed that the previous summer crop in the two rotations significantly influenced oat growth and physiology. Oat grown in the sod-based rotation had greater biomass, leaf chlorophyll and NO3-N concentrations as compared with oat grown in the conventional rotation. At pre-heading stage, oat in the sod-based rotation had 44% greater biomass and 32% higher N uptake than oat in the conventional rotation; oat following peanut produced 40 to 49% more biomass and accumulated 27 to 66% more N than oat following cotton. Therefore, the sod-based rotation improved not only summer crops, but also the winter cover crop. Increased oat growth and N status from the sod-based rotation indicated greater soil quality and sustainability. bahiagrass / crop rotation/ oat biomass / nitrogen uptake / soil quality / sustainability

Pyrosequencing analysis for characterization of soil bacterial populations as affected by an integrated livestock-cotton production system

Bacterial tag-encoded FLX amplicon pyrosequencing of the 16S rDNA gene was used to evaluate bacterial diversity of a clay loam soil (fine, mixed, thermic Torrertic Paleustolls) after 10 years under an integrated livestock (beef)-cotton ( Gossypium hirsutum L.) production system compared to continuous cotton in a semiarid region. In the integrated system, cattle alternatively grazed a perennial warm-season grass [ Bothriochloa bladhii (Retz) S.T. Blake] paddock and small grains grown in two paddocks of a wheat ( Triticum aestivum L.)-fallow-rye ( Secale cereal L.)-cotton rotation. Areas excluded from grazing in the integrated system were also evaluated. Maximum observed number of unique sequences operational taxonomic units (OTU) at 3% dissimilarity level (roughly corresponding to the species level) corresponded to 1200 and 1100 at 0–5 and 5–15 cm depths, respectively. Predominant phyla (up to 65% of abundance) at 0–5 and 5–15 cm in this soil were Proteobacteria, Actinobacteria and Gemmatimonadetes. Proteobacteria were predominant in soil under all components of the integrated livestock-cotton system compared to continuous cotton whereas Bacteroidetes were predominant under continuous cotton. Firmicutes (i.e., Clostridia) and Chlorofexi (i.e., Thermomicrobia) were more abundant in soil under fallow periods of the rotation compared to under cotton (Rye- Cotton-Wheat-Fallow or continuous cotton) or grass (i.e., pasture). The lowest OTUs were detected in soil under fallow periods of the rotation (Wheat- Fallow-Rye-Cotton) compared to the other treatments. Grazing effects were significant for Actinobacteria, Proteobacteria and Chlorofexi. Compared to the continuous cotton system, this study revealed significant changes in bacterial phyla distribution under integrated livestock-cotton systems for a semiarid soil after 10 years. Positive correlations were found between certain bacteria ( Proteobacteria, Firmicutes, Chloroflexi, Verrucomicrobiae and Fibrobacteres) and the activities of alkaline phosphatase and β-glucosidase or β-glucosaminidase.

Comparative Plant Growth and Development in two Cotton Rotations under Irrigated and Non‐Irrigated Conditions

ABSTRACTIncorporating perennial grasses such as bahiagrass (Paspalum notatum Fluegge) to diversify the conventional two‐crop rotation of peanut (Arachis hypogaea L.) and cotton (Gossypium hirsutum L.) prevalent in the U.S. Southeast (SE) is advocated. However, little is reported on growth and development for cotton grown in rotation with perennial grasses. Our objectives were to compare plant characteristics including height, leaf area index (LAI), chlorophyll meter readings (chlorophyll index), N uptake, weed densities, and residual soil nutrients in a conventional rotation of peanut‐cotton‐cotton vs. a bahiagrass‐bahiagrass‐peanut‐cotton rotation. Field studies were conducted in Quincy, FL from 2000 to 2006. Plant height, LAI and N, P, and K uptake were generally greater for cotton in the bahiagrass rotation compared to the conventional cotton/peanut rotation. Weed densities were reduced for cotton in the bahiagrass rotation. Residual nutrients at the end of the season including N, P, and K and soil organic matter (SOM) showed no differences between the rotations. In spite of the improvements in plant growth characteristics, rotating cotton with bahiagrass overall did not improve yield above the conventional rotation. Potential exists for greater cotton yield in the bahiagrass rotation once effective management practices have been identified.

Increased Soil Sorption of Pendimethalin due to Deposition of Guayule‐Derived Detritus

Laboratory sorption experiments were conducted to determine the extent to which soil organic matter derived from guayule (Parthenium argentatum A. Gray) residues can affect the sorption of pendimethalin [N‐(1‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine]. Soils where guayule had been grown for 0 to 38 mo were collected for sorption experiments from beneath actively growing plants. An additional treatment was collected before planting cotton (Gossypium hirsutum L.) in a field 1 yr after the final harvest of guayule that had been grown for 36 mo was also included. Continuous guayule cultivation resulted in a modest increase in soil organic C from 0.29% (±0.01%) to 0.76% (±0.03%) after 38 mo of production. Pendimethalin sorption to the soil increased with increasing guayule organic deposition as measured by time under cultivation. Soils where guayule was grown for 38 mo had an organic C distribution coefficient, KOC, 23 times greater than the control soil where guayule had not been grown (389,400 vs. 16,900 L kg−1). In the treatment before planting cotton, however, the combination of time and cultivation resulted in a reduction of KOC from 389,400 to 21,500 L kg−1 The use of pendimethalin in a guayule–cotton rotation requires sufficient time and primary tillage before planting cotton. In addition, the use of pendimethalin during regrowth of guayule from the stump following harvest may require higher application rates to control weeds. Adsorption of pendimethalin to soil using batch equilibrium indicated that soil beneath actively growing guayule has a higher sorption capacity for pendimethalin than soil without guayule.

Rebuilding Organic Carbon Contents in Coastal Plain Soils Using Conservation Tillage Systems

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 <4% was incorporated into the SOC pool. Levels of SOC in sandy upland soils can be increased at the surface after 6 yr of CT under a corn and cotton rotation, with the increase coming at the expense of an SOC decline at a deeper topsoil depth.

Economic analysis of no tillage and minimum tillage cotton-corn rotations in the Mississippi Delta

Crop rotations have been shown to have agronomic benefits. An increasingly common crop rotation in the Mid-South is cotton rotated with corn. Many previous studies have focused on tillage systems or crop rotations. Few have evaluated a combination of the two (crop rotations and tillage) especially from an economics perspective. Field studies were conducted at Stoneville, MS for the period 2001–2006. Treatments included no till continuous cotton, minimum till continuous cotton, one year corn followed by two years cotton no till, one year corn followed by two years cotton minimum till, one year corn-one year cotton no till and one year corn-one year cotton minimum till. Results revealed that cotton yields were increased in all four systems rotated with corn. Lower risk was associated with minimum till cotton. Gross returns were higher in a monoculture minimum till cotton system. Net returns were larger in a system that included minimum tillage and a corn rotation. The highest net returns and lowest risk were obtained from a minimum till system of cotton rotated with corn every other year. For those producers required to use a no till system, a one year corn-two year cotton rotation provided the highest net returns and least risk.

Effects of tillage systems on soil organic carbon dynamics, structural stability and crop yields in irrigated wheat (Triticum aestivum L.)–cotton (Gossypium hirsutum L.) rotation in semi-arid Zimbabwe

In southern Africa, tillage research has focused on rainfed smallholder cropping systems, while literature on high-input irrigated cropping systems is limited. We evaluated the effects of conventional (CT), minimum (MT) and no-till (NT) tillage systems on soil organic carbon (SOC), bulk density, water-stable aggregates (WSA), mean weighted diameter (MWD) and crop yields in an irrigated wheat-cotton rotation. Soil data were mon- itored in the first and final year, while yields were monitored seasonally. Average bulk densities (1.5-1.7 Mg m -3 ) were similar among tillage systems, but often exceeded the critical limit (1.60 Mg m -3 )

A review of the changes in soil quality and profitability accomplished by sowing rotation crops after cotton in Australian Vertosols from 1970 to 2006

In agricultural systems, soil quality is thought of in terms of productive land that can maintain or increase farm profitability, as well as conserving soil resources so that future farming generations can make a living. Management practices which can modify soil quality include tillage systems and crop rotations. A major proportion of Australian cotton (Gossypium hirsutum L.) is grown on Vertosols (~75%), of which almost 80% is irrigated. These soils have high clay contents (40–80 g/100 g) and strong shrink–swell capacities, but are frequently sodic at depth and prone to deterioration in soil physical quality if incorrectly managed. Due to extensive yield losses caused by widespread deterioration of soil structure and declining fertility associated with tillage, trafficking, and picking under wet conditions during the middle and late 1970s, a major research program was initiated with the objective of developing soil management systems which could improve cotton yields while concurrently ameliorating and maintaining soil structure and fertility. An outcome of this research was the identification of cotton–winter crop sequences sown in a 1 : 1 rotation as being able to sustain lint yields while at the same time maintaining soil physical quality and minimising fertility decline. Consequently, today, a large proportion (~75%) of Australian cotton is grown in rotation with winter cereals such as wheat (Triticum aestivum L.), or legumes such as faba bean (Vicia faba L.). A second phase of research on cotton rotations in Vertosols was initiated during the early 1990s with the main objective of identifying sustainable cotton–rotation crop sequences; viz. crop sequences which maintained and improved soil quality, minimised disease incidence, facilitated soil organic carbon sequestration, and maximised economic returns and cotton water use efficiency in the major commercial cotton-growing regions of Australia. The objective of this review was to summarise the key findings of both these phases of Australian research with respect to soil quality and profitability, and identify future areas of for research. Wheat rotation crops under irrigated and dryland conditions and in a range of climates where cotton is grown can improve soil quality indicators such as subsoil structure, salinity, and sodicity under irrigated and dryland conditions, while leguminous crops can increase available nitrogen by fixing atmospheric nitrogen, and by reducing N volatilisation and leaching losses. Soil organic carbon in most locations has decreased with time, although the rate of decrease may be reduced by sowing crop sequences that return about 2 kg/m2.crop cycle of residues to the soil, minimising tillage and optimising N inputs. Although the beneficial effects of soil biodiversity on quality of soil are claimed to be many, except for a few studies on soil macrofauna such as ants, conclusive field-based evidence to demonstrate this has not been forthcoming with respect to cotton rotations. In general, lowest average lint yields per hectare were with cotton monoculture. The cotton–wheat systems generally returned higher average gross margins/ML irrigation water than cotton monoculture and other rotation crops. This indicates that where irrigation water, rather than land, is the limiting resource, cotton–wheat systems would be more profitable. Recently, the addition of vetch (Vicia villosa Roth.) to the cotton–wheat system has further improved average cotton yields and profitability. Profitability of cotton–wheat sequences varies with the relative price of cotton to wheat. In comparison with cotton monoculture, cotton–rotation crop sequences may be more resilient to price increases in fuel and fertiliser due to lower overall input costs. The profitability of cotton–rotation crop sequences such as cotton–wheat, where cotton is not sown in the same field every year, is more resilient to fluctuations in the price of cotton lint, fuel and nitrogen fertiliser. This review identified several issues with respect to cotton–rotation crop sequences where knowledge is lacking or very limited. These are: research into ‘new’ crop rotations; comparative soil quality effects of managing rotation crop stubble; machinery attachments for managing rotation crop stubble in situ in permanent bed systems; the minimum amount of crop stubble which needs to be returned per cropping cycle to increase SOC levels from present values; the relative efficacy of C3 and C4 rotation crops in relation to carbon sequestration; the interactions between soil biodiversity and soil physical and chemical quality indicators, and cotton yields; and the effects of sowing rotation crops after cotton on farm and cotton industry economic indicators such as the economic incentives for adopting new cotton rotations, farm level impacts of research and extension investments, and industry- and community/catchment-wide economic modelling of the impact of cotton research and extension activities.

Soil Sampling for Fertilizer Recommendations in Conservation Tillage with Paratill Subsoiling

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.

Performance of Peanut and Cotton in a Bahiagrass Cropping System

Yields for peanut (Arachis hypogaea L.) and cotton (Gossypium hirsutum L.) have reached a plateau in the southeastern USA (SE). This, coupled with environmental concerns and increased production costs, prompt the need to find alternatives to the limited peanut/cotton rotation currently used. Bahiagrass (Paspalum notatum Fluegge) was introduced to the current peanut/cotton cropping system to evaluate its effect on peanut and cotton performance. Our objectives were to compare crop yields in a conventional rotation of cotton‐cotton‐peanut vs. a bahiagrass–bahiagrass–peanut–cotton rotation under irrigated and nonirrigated conditions. Field studies were conducted in Quincy, FL, on a Dothan sandy loam (fine, loamy siliceous, thermic Plinthic Kandiudults) from 2000 to 2004. During 2–3 yr of the study, peanut yields were 900 kg ha−1 greater (averaged across irrigation treatments) following 2 yr of bahiagrass compared with following 2 yr of cotton under both irrigated and nonirrigated conditions. Root biomass was greater for cotton in the bahiagrass rotation compared with cotton in the conventional rotation. The greater root biomass, however, resulted in rank growth and cotton in the bahiagrass rotation yielded the same as cotton in the conventional rotation. It appears potential exists for greater cotton yield in the bahiagrass rotation once effective management practices have been identified.

Benefits of site-specific subsoiling for cotton production in Coastal Plain soils

The negative impacts of soil compaction on crop yields can often be alleviated by subsoiling. However, this subsoiling operation is often conducted at unnecessarily deep depths wasting energy and excessively disturbing surface residue necessary for erosion control and improved soil quality. A corn ( Zea mays L.)–cotton ( Gossypium hirsutum L.) rotation experiment was conducted over 4 years on a Coastal Plain soil with a hardpan in east-central Alabama to evaluate the potential for site-specific subsoiling (tilling just deep enough to eliminate the hardpan layer) to improve crop yields while conserving energy. Seed cotton yield showed benefits of subsoiling (2342 kg/ha) compared to the no-subsoiling treatment (2059 kg/ha). Averaging over all years of the study, site-specific subsoiling produced cotton yields (2274 kg/ha) statistically equivalent to uniform deep subsoiling at a 45 cm depth (2410 kg/ha) while not excessively disturbing surface soil and residues. Significant reductions in draft force were found for site-specific subsoiling (59% and 35%) as compared to uniform deep subsoiling at a 45 cm depth in shallow depth hardpan plots (25 cm) and medium depth hardpan plots (35 cm), respectively. Calculated fuel use for site-specific subsoiling was found to be reduced by 43% and 27% in the shallow and medium depth hardpan plots, respectively, as compared to uniform deep subsoiling in these same plots. Producers in the Coastal Plains who can determine (or who know) the depth of their root-impeding layer and perform site-specific subsoiling can have comparable cotton yields to traditional uniform depth subsoiling with reduced energy requirements.

Stratification of nutrients in soil for different tillage regimes and cotton rotations

Crop management practices, especially tillage and rotation, can impact soil nutrient stratification, crop growth, and yield. The objectives of this study were to determine the soil-profile distribution of plant-available nutrients in four depth intervals from 0 to 90 cm for different cotton ( Gossypium hirsutum L.) cropping systems, tillage regimes, and N fertilization rates in a south-central Texas silty clay loam soil after 5 years of treatment imposition. Distribution of nutrients in the soil profile varied between cropping systems (continuous cotton monoculture and cotton–corn ( Zea mays L.) rotation), conventional (CT) and reduced tillage (RT), and N fertilization rates (0, 80, and 160 kg N ha −1). Plant-available P showed the greatest stratification and was 426% higher at 0–15 cm than at 60–90 cm, while SO 4 had the greatest increase (42%) with depth. The percentage decrease from 0–15 to 60–90 cm was 47% and 147% for NO 3 and K, and 76%, 12%, 43%, and 232% for Mn, Fe, Cu, and Zn, respectively. In contrast, Ca and Mg concentrations increased 22% and 15%, respectively, from 0–15 to 60–90 cm. Increasing the N fertilization rate increased plant-available NO 3 and SO 4 but decreased K, Fe, Cu, and Zn concentrations. Inclusion of corn in rotation with cotton decreased plant-available Mn, Fe, and Cu from 15 to 90 cm relative to continuous cotton at 160 kg N ha −1. For unfertilized soil, rotation increased micronutrient concentrations at 15–60 cm compared to continuous cotton. On average, CT cotton–corn had significantly lower K, Ca, Mg, Na, and SO 4 concentrations than CT continuous cotton. Reduced tillage and diversified cropping systems altered the distribution of plant-available nutrients in soil relative to CT and continuous cotton. In fact, RT increased plant-available P and NO 3 in surface soil, which may have contributed to higher lint yields than CT continuous cotton.

Cotton Roots, Earthworms, and Infiltration Characteristics in Sod–Peanut–Cotton Cropping Systems

Diverse cropping systems offer many advantages to farmers. We evaluated root growth, soil water infiltration, and earthworm population densities in a conventional peanut (Arachis hypogaea L.)/cotton (Gossypium hirsutum L.) rotation using conservation tillage (CT), and a peanut/cotton/bahiagrass (Paspalum notatum Fluegge) farming system. The rotations were initiated in 2000 in Quincy, FL, and in 2001 in Headland, AL, in both cases on a Dothan sandy loam (fine, loamy siliceous, thermic Plinthic Kandiudults). In 2003, a year with more uniform rainfall, cotton in the sod‐based rotation had larger average crown root diameter per plant (22.6 vs. 16.3 mm), root area (87.2 vs. 57.4 cm2), root length (640 vs. 460 cm), and root biomass (18.59 vs. 10.45 g) as compared with cotton in the peanut/cotton rotation. Water infiltration rates were higher in both cotton and peanut after bahiagrass compared with the conventional peanut/cotton rotation in 2003. Earthworm population densities were greater in the sod rotation compared with the traditional peanut/cotton cropping system. Water infiltration was positively correlated to earthworm population densities. Despite the improvements in soil quality, cotton yield in the sod rotation was the same as the traditional cropping systems. Cotton developed excessive vegetative growth in the bahiagrass system at the expense of lint yield. Further research is needed to determine the N rate for the sod‐based rotation in comparison with the conventional cotton/peanut rotation.

Tillage and Cover Cropping Effects on Aggregate‐Protected Carbon in Cotton and Tomato

Conservation tillage (CT) and cover cropping (CC) are agricultural practices that may provide solutions to address water and air quality issues arising from intensive agricultural practices. This study investigated how CT and CC affect soil organic matter dynamics in a cotton(Gossypium hirsutum L.)–tomato (Lycopersicon esculentum Mill.) rotation in California's San Joaquin Valley. There were four treatments: conservation tillage, no cover crop (CTNO); conservation tillage with cover crop (CTCC); standard tillage, no cover crop (STNO); and standard tillage with cover crop (STCC). After 5 yr, the top 30 cm of soil in CTCC had an increase of 4500 kg C ha−1, compared with an increase of 3800 kg C ha−1 in STCC from initial soil C content in 1999. To enhance our understanding of C dynamics in CT systems, we pulse‐labeled cotton with 13CO2 in the field and followed the decomposition of both the roots and the shoots through three physical fractions: light fraction (LF), which tends to turnover quickly, and two relatively stable C pools—intraaggregate LF (iLF) and mineral‐associated carbon (mC). Soil under CT treatments retained more of the cotton‐residue‐derived C in LF and iLF than ST 3 mo after placement in the field. These differences disappeared after 1 yr, however, with no discernable differences between CT and ST regardless of CC. In California's Mediterranean climate, CT alone does not accumulate or stabilize more C than ST in tomato–cotton rotations, and the addition of cover crop biomass is more important than tillage reduction for total soil C accumulation.