Surface Mulch Research Articles

Parthenium hysterophorus Herbage Mulching: a Potential Source of Weeds Control in Soybean (Glycine max)

ABSTRACT: Weeds have indirect effects on crop plants. Crop development is affected by allelopathy from certain weed species. Allelochemicals from allelopathic weeds can disturb the root and shoot growth of emerging crop seedlings, as well as cause several other types of damage. A study was carried out to investigate the allelopathic potential of Parthenium hysterophorus for weed response in soybean. The experiment was laid out in Randomized Complete Block Design (RCBD) with split plot arrangements and replicated thrice. Sowing methods (broadcast and line sowing) were kept in the main plot and mulching treatments (surface mulching and soil incorporation) were kept in the sub-plots. Mulching of Parthenium hysterophorus was applied at the rate of 1.0 t ha-1, 2.5 t ha-1, 5 t ha-1 with control (no parthenium). Manual weed control was also used as treatments. The results revealed that significantly higher shoot length, shoot fresh weight, shoot dry weight, root length, root fresh weigh, root dry weight, number of nodules per plant, nodules fresh and dry weight, number of branches, number of pods per plant, thousand seed weight biological yield, economic yield, dry matter yield and harvest index were recorded with the soil incorporation of Parthenium herbage at the rate of 2.5 t ha-1. Maximum weed density and weed dry biomass were recorded in control plots while weed control efficiency was seen greater in plots where Parthenium herbage was applied to surface at the rate of 5 t ha-1. The results suggested that the use of Parthenium hysterophorus herbage mulching can reduce infestation of weeds by its allelopathic effects and increase the yield of soybean under sub-humid agro-climatic conditions.

Surface mulching and a sandy soil interlayer suppress upward enrichment of salt ions in salt-contaminated field

Purpose The suppression effect of a sandy soil interlayer on topsoil enrichment of salt ions was investigated. However, whether this suppression effect was enhanced by surface mulching was little documented. The objectives of this study were to compare the suppression effects under different materials mulching, and to investigate an innovative method to suppress the soil salt ions down-to-top enrichment.

Short-term effects of tillage and residue management practices on dry matter yield and fate of 15N-urea in a continuous maize cropping system under subtropical conditions

In the Indo-Gangetic plains of south Asia, conventional tillage (CT) and removal of crop residues have been the major cause of declining soil fertility. While zero tillage (ZT) farming combined with retention of crop residues as surface mulch are well known to improve soil quality and crop productivity in different climatic zones, only limited knowledge exists on the performance ZT technology in the Indo-Gangetic plains. A field study was conducted under subtropical arid climate to elucidate short-term effects of different tillage, residue mulch and N fertilizer regimes on the productivity of irrigated maize grown for five cropping seasons. Treatments included CT and ZT; each with mulch (M+) or without mulch (M−), and with N (N+) or without N (N−). Fate of the fertilizer-N applied to the 5th maize crop was also investigated using 15N tracer. After five cropping seasons, soil organic C (SOC) in the arable soil layer was higher under ZT compared to CT (29% increase), under M+ compared to M− (16% increase) and under N+ compared to N− (13% increase). Highest SOC was recorded under ZT-M+-N+ treatment (19.1 Mg ha−1) and the lowest under CT-M−-N− (10.7 Mg ha−1). Nitrogen application increased the grain yield; the increase was higher under ZT than under CT in three cropping seasons. Mulch application reduced the grain yield in four cropping seasons. During all growing seasons, the grain as well as total biomass yields were highest under ZT-M−-N+. Recovery of the fertilizer-N in soil (0–100 cm depth) ranged from 28 to 39% of the applied with lowest recorded under ZT-M−. The fertilizer-N recovery in plant was highest (40%) under ZT-M−, whereas the total fertilizer N recovery in the soil-plant system was not influenced by tillage or mulch regimes. Plant-N derived from soil (Ndfs) was higher under ZT compared to CT (47% increase), and under M+ compared to M− (15% increase); the highest Ndfs was recorded under ZT-M− (31–68% increase). While mulch had no effect on the added-nitrogen-interaction, the latter was significantly higher under CT compared to ZT (65% increase). Results suggested that as compared to other tillage/mulch regimes, ZT without mulch produced similar or higher grain yield and showed highest fertilizer-N use efficiency in continuous maize cropping system under subtropical conditions prevailing in the Central Punjab, Pakistan.

Cover crop species and termination method effects on organic maize and soybean

Mechanical cover crop (CC) termination can reduce tillage in organic rotations, but research is needed to develop recommendations for producers in the upper Midwest, U.S.A. Field studies were conducted near Concord, NE, U.S.A., in 2008–2009 and 2009–2010. This study compared no-till [roller/crimper (CRIMP) and broadcast propane flame (FLAME)] and spring disk (DISK) termination of legume, grass, and broadleaf CCs and their effects on a subsequent maize or soybean crop. Before sowing the grain, overwintering CC species were terminated; frost-killed (FROST) CCs were also disked in the spring. Weeds were controlled via cultivation in the tilled systems (DISK and FROST); CC residue was left as a surface mulch in the no-till systems (CRIMP and FLAME). Termination method/tillage regime had greater influence than CC species on grain yield and quality, with tilled treatments performing better than CRIMP and FLAME, likely due to early season weed pressure and low stand establishment in the no-till treatments. Maize yield for the DISK system was on average 6.8 Mg ha−1 in both trials, while FLAME and CRIMP produced 57–78% less. Soybean yields for DISK were 3.3 and 2.0 Mg ha−1; CRIMP and FLAME produced 21–33% less in 2009 and 56% less in 2010. The CCs best suited to no-till systems were winter rye (superior biomass) and hairy vetch (successful mechanical termination). FLAME performed as well as CRIMP. The results suggested that no-till CC termination should be employed within a comprehensive weed management system to minimise yield losses due to weeds and CC regrowth.

Soil moisture loss reduction owing to evaporation

Soil-climatic conditions of arid regions of Russia have a great potential for obtaining high yields of various crops, but the constant lack of soil moisture hampers the increase in production volumes. However, the deficiency of soil moisture is due not only to a lack of atmospheric precipitation, but also to inefficient saving. Moisture losses because of unproductive evaporation reach 40-70 percent of atmospheric precipitation. One of the effective ways to accumulate and conserve soil moisture is the autumn shallow mulching tillage, which creates a loosened top layer of soil with a mulched surface. The top layer of soil during loosening and mulching promotes the accumulation and conservation of moisture not only in the upper, but also in the deeper soil horizons. A new combined tillage tool was developed and manufactured to implement such tillage. The tool is equipped with 2 batteries of knife disks placed in two rows one behind the other, with flat hoes arranged in two rows in staggered order, and a roller with pins mounted on its working surface. When soil cultivation by the proposed tool, a qualitatively loosened layer with a mulch surface is created. Enhanced water permeability and moisture capacity increase the penetration of atmospheric precipitation into the soil and reduce the loss of moisture owing to evaporation. The research carried out to determine the loss of moisture due to evaporation, depending on the type and quality of soil cultivation, have confirmed the advantage of the proposed type of tillage. The reserves of productive moisture in a 1 m soil layer increase by 31.8; 25.8 and 16.8 mm in comparison with fields without tillage, shallow tillage by disc mulcher DM-5.2 and by cultivator KPIR-3.6 respectively. The productivity of barley variety Volgar' at the area cultivated by experimental tools was 2.24 t per hectar, by KPIR-3.6 – 2.12 t, DM-5.2 – 2.02 t, without tillage – 1.46 t per hectar.

Effects of Rainfall-Induced Topsoil Structure Changes on Root-Zone Moisture Regime during the Dry Period

Rainfall erosion and subsequent intermittent drought are serious barriers for agricultural production in the subtropical red soil region of China. Although it is widely recognized that rainfall-induced soil structure degradation reduced soil water storage and water-holding capacity, the effects of variation of the rainfall-induced topsoil structure on the subsequent soil water regime during the dry period is still rarely considered. The objective of this study was to ascertain the way of rainfall-induced topsoil structure changes on the subsequent soil water regime during the dry period. In a three-year-long experiment, six practices (CK, only crop; SM, straw mulching; PAM, polyacrylamide surface application; B, contour Bahia-grass strip; SPAM, straw mulching and polyacrylamide surface application; and BPAM, contour Bahia-grass strip and polyacrylamide surface application) were conducted at an 8° farmland with planting summer maize resulting in different topsoil structure and root-zone moisture, to establish and reveal the quantitatively relationship between the factors of topsoil structure and soil drought. Rainfall erosion significantly increased the soil crust coverage, and decreased the WSA0.25, 0–30 mm soil porosity and mean pore size. There was no significant difference during the raining stage of root-zone water storage between CK and other practices. An index of soil drought intensity (I) and degree (D) was established using soil water loss rate and soil drought severity. The larger value of I means a higher rate of water loss. The larger value of D means more severe drought. During the dry period, I and D were significantly higher in CK than in other practices. I and D had significantly positively correlation with the crust size and crust coverage, and negatively with WSA0.25, 15–30 mm soil porosity and mean pore size. Among of soil structure factors, the soil porosity had the largest effect on I and D. The rainfall-induced topsoil structure changes greatly deteriorated the root-zone regime during the dry period mainly due to significant increasing soil water loss but little improving the raining stage of soil water storage. Straw mulching had greater effects than other practices in alleviating rainfall-induced erosion and intermittent drought, and could be a better strategy applied for this region.

Mechanism of Sunlight Damage on Drip Tape by Pendant Droplets in Mulched Drip Irrigation

Abstract. Drip irrigation under mulch has been applied in China for nearly 20 years, but sunlight damage from the lens effect through droplets beneath clear plastic mulch is always a problem that cannot be ignored. Droplet volume and mulch wettability affect the geometric parameters of the pendant droplets. Changes in geometric parameters were experimentally investigated by analyzing side-view images of droplets. Models were built to predict droplet focal length and light-gathering power based on the geometric parameters. A comparison between numerical and optical experimental results suggested that the focal length model was accurate and reliable. The effective incident area of the parallel light proposed in this study could also be used to represent the light-gathering power, which had a relationship with the drip tape burning rate. The increase in wettability of the clear mulch considerably increased the focal length of the pendant droplets, expanded the focal length range, enhanced the light-gathering power, and thus increased the risk of drip tape burning. In practice, pendant droplets with a wetting radius of 3 to 5 mm, with corresponding focal lengths of 5 to 12 mm, have a high probability of emergence. Therefore, the distance between the mulch and drip tape should be beyond this focal length range to reduce the risk of drip tape burning by pendant droplets. In addition, filming the mulch surface with hydrophobic materials to increase the contact angles of droplets can also protect the drip tape from sunlight damage. Keywords: Drip irrigation under mulch, Drip tape burning, Effective incident area of parallel light, Focal length, Pendant droplet.

Soil biochemical changes at different wheat growth stages in response to conservation agriculture practices in a rice-wheat system of north-western India

Intensive tillage, removal or burning of crop residues, limited organic manure use, declining irrigation water resources and scarcity of labour are the major causes of soil degradation and unsustainability of rice (Oryza sativa L.)–wheat (Triticum aestivum L.) system (RWS) in South Asia.Resource conservation technologies (RCTs) such as zero tillage (ZT), dry direct seeded rice (DSR) and crop residues retained as mulch have shown promise to increase the productivity and profitability of RWS in South Asia. Effects of RCTs on soil biological parameters are unclear and contradictory. We evaluated the effects of conservation agriculture practices on changes in soil biochemical properties at different growth stages of wheat grown as the fifth crop in RWS. Twelve treatment combinations of tillage, crop establishment and crop residue management included four main plot treatments in rice: (1) conventional tillage (CT)-DSR,(2) ZT-DSR, (3) DTR, ZT machine transplanted rice and (4) PTR, conventional puddled transplanted rice. The three subplot treatments were: (i) CTW-R, CT wheat with both rice and wheat residues removed, (ii) ZTW-R, ZT wheat with residues of both the crops removed and (iii) ZTW+R, ZT wheat with rice residue retained as surface mulch in subsequent wheat. Irrespective of rice establishment methods, mean wheat grain yield under ZTW+R was 6% and 10% greater than CTW-R and ZTW-R respectively. Soil enzyme activities increased (5–18%) under ZTW+R compared with ZTW-R and CTW-R at different growth stages of wheat. The residual effect of rice establishment methods was significant on soil enzyme activities during wheat cropping, which were highest under ZT-DSR followed by CT-DSR, DTR and PTR. Soil organic carbon content in the 0–7.5 cm layer was significantly higher (7–9%) under the ZTW+R treatment compared with all the other treatments. Principal component analysis (PCA) identified three enzyme activities (dehydrogenase, fluorescein diacetate and phosphatase), and soil organic carbon content as the most sensitive indicators for assessing soil quality for RWS based on conservation agriculture. The PCA discriminated rice establishment systems with rice residue as surface mulch from rice establishment systems without rice residue and the maximum tillering stage from the other stages of wheat. The present study provided reliable biochemical indicators to monitor soil biological quality changes in response to conservation agriculture practices in RWS.

Leachability and potential ecotoxic impact of trifluralin-impregnated mulch.

The leachability, potential ecotoxicity, and photolysis of trifluralin-impregnated mulch, a popular retail consumer gardening product, were investigated under environmentally realistic conditions. Leachability of trifluralin from impregnated mulch was low (<1% of total extractable compound) and in the range of reported values for agricultural soils. No trifluralin transformation products were detected in mulch leachate. Yeast-based estrogenicity and androgenicity screens indicated that aqueous trifluralin is not estrogenic but is moderately androgenic at concentrations ~1e-5M. Impregnated mulch leachate was not hormonally active, even at undiluted concentrations, but it did exert nonspecific toxicity at dilutions of ~1:10. Photolysis of trifluralin was investigated in acetonitrile and water and on mulch surfaces. Degradation on mulch surfaces was diffusion-limited; it was ~17 times slower than in aqueous solution, but faster than has been reported on kaolinite. An array of trifluralin transformation products was identified, but in no case did they exceed 10% of the parent compound. Using industry-recommended application guidelines, it is estimated that as much as 1400μg/m2 of trifluralin may leach from impregnated mulch upon the first rainfall. However, provided that consumers are aware that such mulch products contain trifluralin and are properly educated about its use, the potential for direct ecotoxic impact is likely to be small.

Yield loss compensation effect and water use efficiency of winter wheat under double-blank row mulching and limited irrigation in northern China

Maize straw residues as a surface mulching material would be an effective soil water-saving practice in wheat production for a wheat-maize rotation system in northern China. Additionally, combining a mulching pattern and limited irrigation could play an important role in enhancing the productivity of winter wheat. Therefore, open field experiments were carried out during 2012–2014 to study soil water content in depth, water use efficiency (WUE), soil temperature, wheat grain yield and root parameters under a mulching pattern [each-row mulching (ERM) and double-blank row mulching (DRM) with three mulching masses of 0. 4.5 and 9.0tha−1] and limited irrigation [no irrigation (I0) and one-time irrigation in winter (I1)].Results indicated that wheat yields increased (mean 3.3%) or decreased (mean 5.4%) a little under ERM groups with no irrigation. Irrigation for each row of mulch increased the wheat yield (mean 8.8%). With or without irrigation, yields under DRM0 were lower compared to ERM0, whereas, DRM4.5 and DRM9.0 had a higher grain yield than ERM4.5 and ERM9.0 (mean 25% under I0 and 18.8% under I1) as well as DRM0 (mean 24.1%). The DRM patterns with a high yield could have an equal effect with irrigation in winter. Additionally, irrigation could enhance the effects of DRM on wheat yield increase (mean 6.87tha−1in DRM4.5 and 7.06tha−1 in DRM9.0). Effective tillers and above-ground biomass would be the key factors for determining wheat yield, especially under certain mulching patterns, although these effects were not reflected in wheat roots.Mulching on soil temperature had a more significant difference in an early growth period than the later stages of wheat. An additional feature was that the DRM pattern had a persistent heat preservation effect in the regrowth stage, while there was a lower soil temperature in ERM groups in this stage when there was no irrigation. Mulching managed to shorten the period of negative accumulated temperatures of wheat (mean of 7days under ERM and 15days under DRM) under I0. Winter water irrigation enhanced the shorten effect to a certain extent. Mulching had a more significant water conservation effect in the overwinter stage with lower precipitation and higher soil evaporation. Soil water content under DRM groups was richer than ERM groups in the late growth stage, when there was lower plant density and evapotranspiration, but there was a higher yield and WUE (with a mean of 18.6% under I0 and 20.3% under I1).The results suggest that the DRM pattern optimizes soil temperature, water content, balance roots and group effects as well as increasing wheat yield. Thus, this approach could be a better field management option for wheat growth and yield production under the limitations of water in northern China.

Effects of different mulching technologies on evapotranspiration and summer maize growth

Different mulching techniques, i.e., plastic film, gravel-sand and straw, have been applied in China for many decades, but have not been compared systematically for effects on soil water storage, evapotranspiration, crop growth, yields and water use efficiency (WUE) various crop growth stages. A Two-year summer maize growth experiment was conducted in containers under a rain-shelter to analyze the effects of plastic film, gravel-sand and straw surface mulches on soil water dynamics and crop growth processes. A lysimeter was designed for each container to dynamically measure soil-plant water dynamics. Eight treatments were designed including a control (no mulching – CK), black plastic-film-mulch (BPF0), transparent plastic-film-mulches(TRPF0), 1-mm-straw below black plastic film (BPF1), 1-mm-straw below transparent film (TRPF1), and 69kg/m2 gravel-sand-mulch (SAND), two straw mulch treatments with chopped-straw-length of 1mm (ST1) and 100mm (ST100). The results revealed that, all 7 mulching treatments decreased soil water evaporation during early crop growth stages, which saved water and accelerated maize growth in the middle and later stages. For the 2015 and 2016 growing seasons, average soil water storage during the jointing stage increased 32%, 39%, 48%, 57%, 61%, 62% and 66%, yield increased 13%, 18%, 23%, 28%, 29%, 34% and 29%, and WUE increased 1.4, 2.1, 3.0, 3.2, 3.5, 4.1, and 3.6kghm−2mm−1 compared with the CK treatment, for the ST100, SAND, ST1, TRPF0, TRPF1, BPF0 and BPF1 treatments, respectively. In general, yield and WUE increases were greatest in the BPF0 treatment, followed by TRPF1, BPF1, TRPF0, ST1, SAND and ST100. Yield and WUE increases in the ST100 and SAND treatments were small. This research revealed that plastic mulch had the largest yield and WUE increase, of which, black plastic film was better than transparent plastic film. The yield and WUE increase of gravel-sand-mulching was larger than 100-mm-in-length-straw-mulching but less than 1-mm-in-length-straw-mulching.

Conservation agriculture improves yield and reduces weeding activity in sandy soils of Cambodia

The years of intensive tillage in Cambodia have caused significant decline in agriculture’s natural resources that could threaten its future of agricultural production and sustainability. Conventional tillage could cause rapid loss of soil organic matter, leading to a high potential for soil degradation and decline of environmental quality. Hence, a better and comprehensive process-based understanding of differential effects of tillage systems and crop management on crop yield is critically needed. A study was conducted in 10 farmer’s fields to evaluate the effect of conservation agriculture and conventional tillage on yield of selected crops and weeding activity in two villages of Siem Reap, Cambodia. The experiment was laid out following a 2 × 2 factorial treatment combination in randomized complete block design. Each treatment was replicated five times. Each farmer’s field was divided into four plots and was randomly assigned with production management and irrigation treatments, respectively. We demonstrated that our results supported the overall premises of conservation agriculture. Average yields of selected crops were significantly (≤ 0.001) improved in plots with conservation agriculture (17.1 ± 6.3 to 89.3 ± 40.2 Mg ha−1) compared with conventional tillage (18.8 ± 6.4 to 63.8 ± 27.7 Mg ha−1). Our results showed that manual weeding in all cropping seasons was significantly reduced by about 35% in conservation agriculture (169 ± 23 to 125 ± 18 man-day ha−1), which can be attributed to existing cover crops and surface mulch. Overall, our results suggest that in smallholder commercial household farms, adoption of conservation agriculture had a profitable production management system, which could save natural resources, improve yield, and reduce labor. We proved for the first time that in Cambodian smallholder commercial household farms, adoption of conservation agriculture saves natural resources, improves yield, and reduces labor. Additional studies are encouraged to further test the conservation agriculture system for a longer period of time, with repeated cropping sequences.

Effects of Previous Wheat Straw on the Yield of Maize in the Oasis Irrigation Region

The surface mulch effects on maize (Zea mays L.) production are not well studied. Higher yield depends on coordinated development among the yield components of crops. The purpose of this study was to determine whether plastic film combined with four straw management systems (no tillage with straw standing [NTSS]; no tillage with straw covering [NTS]; tillage with straw incorporation [TIS]; and conventional tillage without straw retention [CT]) could boost grain yield of maize via increasing leaf area index and yield components. This study was conducted in a wheat (Triticum aestivum L.)–maize rotation system from 2009 to 2012 in northwestern China. Plastic film combined with straw retention boosted grain yield by 4.5 to 17.5%, especially, NTS had the highest increasing effect, boosted grain yield by 13.7 to 17.5%, and improved harvest index by 5.4 to 8.4%, compared to CT. Plastic film combined with straw retention significantly increased yield components of maize. Among the three straw retention treatments, NTS increased the maize ear number (EN) by 18.1 to 21.0%, increased the kernel number per ear (KNE) by 63.7 to 67.8%, increased the thousand‐kernel weight (TKW) by 8.7 to 9.6%, compared to CT. Straw retention decreased the maize leaf area index (LAI) before the silking stage and increased the LAI after the silking stage, which effectively regulated the growth and development of maize at early and late stages of development, NTS had the best regulating effect. Path analysis indicated that the integrated system with plastic film combined with straw retention increased the maize grain yield by improving the KNE. We conclude that plastic film combined with previous straw covering can be an effective system for boosting crop productivity by improving the yield components and optimizing LAI dynamics under limited resources in arid environments.

Woody organic amendments for retaining soil water, improving soil properties and enhancing plant growth in desertified soils of Ningxia, China

Extreme soil degradation is one of the most serious problems affecting dryland ecosystem health and agricultural production globally. This study was conducted to investigate the potential for using woody amendments to improve soil moisture availability, soil microbial activity, soil fertility, and plant growth in desertified soils in Ningxia, China. Soil amendments of wood chips derived from tree branches of four readily available tree species (poplar, elm, pagoda tree, and grapevine), were evaluated and compared with more commonly used wheat straw, rice husks, and cow manure, using replicated microcosm experiments. Different types, concentrations, and application techniques of woody and non-woody organic amendments were compared for their impacts on soil moisture, soil chemistry, microbial activity, and plant growth. The treatments with woody organic materials incorporated into the soil consistently demonstrated an improvement in soil water status, increased organic C content, and improved soil fertility, and also resulted in enhanced microbial activity, and wheat growth. Although surface mulch increased soil water storage and enhanced wheat growth, it did not effectively improve soil microbial activity as compared with wood incorporated into the soil. Differences in placement and type of amendment differ markedly in their effects on physical, chemical and biological soil responses. A combination of 5% poplar wood chips incorporated into the soil with a lattice of twigs over the soil was ideal for simultaneously maximizing soil water availability, encouraging microbial activity, and maximizing wheat yield. In conclusion, woody materials from locally available trees can serve as a valuable amendment for desertified soils in Ningxia and other places of Northern China by increasing rainfall capture, reducing irrigation demand, improving soil health and promoting higher crop yields.

Halosulfuron-Methyl Degradation from the Surface of Low-Density Polyethylene Mulch Using Analytical and Bioassay Techniques

Vegetable injury and yield loss has occurred when applying halosulfuron to low-density polyethylene mulch (LDPE) prior to transplanting. Research determined vegetable crop response to halosulfuron applied over LDPE mulch from 1 to 28 d prior to transplanting using (1) temperature effects in aqueous solution in laboratory experiments, (2) analytical evaluation of degradation from LDPE under field conditions, and (3) a field bioassay. Halosulfuron stability was evaluated on a thermal gradient table for temperatures at 10 to 42 C for 15 d. Half-life was inversely related to temperatures ranging from 38.5 d at 20 C to 3.2 d at 42 C, with little to no degradation at temperatures of 11 and 15 C. Analytical data indicated that the field half-life of halosulfuron at 26 or 52 g ha−1applied to LDPE mulch under dry conditions was 2.6 and 2.8 d, respectively. Given the changes in the microclimate effects at the mulch surface by absorption of solar radiation, daily thermal energy quantified halosulfuron degradation (at the same rates) to be 51 and 55 MJ m−2, respectively. At 21 d after treatment (DAT), 90% of halosulfuron had dissipated from the mulch, with none detectable 35 DAT under dry conditions. When watermelon or yellow crookneck squash was transplanted into mulch previously treated with halosulfuron at 79 g ha−1, plant growth and development were equal to nontreated controls as long as there was a 14 d prior to transplant (DPT) interval accompanied by 13.5 cm of rain, or a 17 DPT interval accompanied by 6.2 cm of rain. However, at 79 g ha−1applied at 9 or 1 DPT in 2013, and 1 DPT in 2014, halosulfuron injured yellow squash and reduced yield and fruit number. Halosulfuron at 79 g ha−1applied 1 DPT significantly reduced watermelon yield in 2013, which was confirmed by vine length and plant biomass reductions in 2014. Halosulfuron POST controlsCyperusspp. in mulch vegetable production, but time and rainfall are required for dissipation to occur in order to prevent injury and yield loss.

Agronomic evaluation of seedbed and mulching alternatives with plant spacing for dry‐season fluted pumpkin in coarse‐textured tropical soil

AbstractFluted pumpkin (Telfairia occidentalis) has high agronomic and food relevance in the tropics. Production of this vegetable in the dry season with irrigation is increasingly popular and is mostly on droughty soils, thus requiring research on appropriate combination of soil moisture conservation/management practices. This study evaluated the interactions among seedbed configuration (flat and raised), surface mulching (grass‐mulched and no‐mulch) and plant spacing (1002, 502 and 252 cm2, designated wide, intermediate and close spacing, respectively) on fluted pumpkin performance in a sandy‐loam soil in southeastern Nigeria during 2014/2015 dry season. Seedling emergence (ratio of emerged to expected seedlings) was highest and lowest in flat/mulched/wide and flat/no‐mulch/close combinations, respectively. Main effects showed higher seedling emergence in mulched (67.9%) than no‐mulch plots (53.1%) and in wide (70.8%) and intermediate spacing (64.6%) compared to close spacing (46.0%). Fresh leaf yield assessed biweekly during 6–14 weeks after sowing was generally highest and lowest in flat/mulched/close and flat/no‐mulch/wide combinations, respectively. Seedbed configuration had no distinct effect on leaf yield; hence, flat/mulched/close option was similar to raised/mulched/close option. Yields from mulched/wide and no‐mulch/close options were similar with a mean (2735 kg/ha) approximating the overall mean (2868 kg/ha). Flat/mulched/close combination is the best management practice to grow fluted pumpkin with irrigation on droughty soils during the dry season of the tropics. Where this best practice is compromised due to mulch or seed scarcity, the ensuing no‐mulch/close and mulched/wide, respectively can support dry‐season production of pumpkin in droughty tropical soils at average levels.

Using Reduced Tillage and Cover Crop Residue to Manage Weeds in Organic Vegetable Production

Adoption of conservation tillage practices has been slow in organic vegetable production, partially due to producers’ concerns regarding weed management. Integrating cover crops into a conservation tillage program may provide organic producers a viable weed management option enabling growers to practice conservation tillage. A four-year study was conducted to evaluate the influence of different tillage methods (two conventional and two conservation practices) jointly with a mixed winter cover crop for weed suppression, time required for hand weeding, and crop yield in organically managed eggplant (2012 and 2014) and sweet corn (2013 and 2015) production systems. Tillage treatments were conventional tillage without surface mulch (CT-BG) and with black polyethylene (plastic) mulch (CT-BP), strip-tillage (ST), and no-tillage (NT) with cover crop residue. At 2 and 7 WAT/P (weeks after transplanting/planting), intra-row weed density was higher in CT-BG and ST, and inter-row weed density was higher in CT-BG and CT-BP treatments. Time required for hand-weeding was greatest in CT-BG and least in CT-BP and NT treatments. Eggplant yield was lowest in NT treatment in 2012 but similar among treatments in 2014. Sweet corn yield was similar among treatments in 2013 but highest in ST in 2015. Though both CT-BP and NT treatments showed greater potential for weed suppression, production input was highest in CT-BP but least in NT. Implications of these findings suggest that there is a potential to use strip tillage integrating with stale seedbed tactic for weed management in organic vegetables, which reduces herbicide use, hand-labor, and overall weed management cost while maintaining high yield potential.

Role of Different in-situ Soil Moisture Conservation Practices on Growth of Large Cardamom in Sikkim

Role of Different in-situ Soil Moisture Conservation Practices on Growth of Large Cardamom in Sikkim A field experiment was conducted during 2014-15 at Indian Cardamom Research Institute, Regional Research Station, Spices Board research farm in Kabi (1567 m amsl) Sikkim. Among the moisture conservation practices, treatment having trench across slope duly filled with biomass recorded the significantly higher number of immature tillers (5.98 & 5.79), mature tillers (4.01 & 5.82) and vegetative buds (4.00) per large cardamom clump. With respect to soil moisture content, all the soil moisture conservation practices significantly improved the soil moisture content over the control at all the stages of observation. Among the soil moisture conservation practices, surface mulching recorded significantly higher values of soil moisture i.e. 21.00, 21.50, 19.60, 17.60 and 21.70 per cent on 30th November 2014, 31st December 2014, 31st January 2015, 28th February 2015 and 31st March 2015 respectively. Surface mulching conserved higher soil moisture as compared to the control.

Northern Highbush Blueberry Cultivars Differed in Yield and Fruit Quality in Two Organic Production Systems from Planting to Maturity

Northern highbush blueberry (Vaccinium corymbosum L.) cultivars were evaluated from planting (Oct. 2006) through 2014 in a certified organic research site in Aurora, OR. The treatments included cultivar (Duke, Bluecrop, Reka, Bluejay, Bluegold, Draper, Legacy, Liberty, Ozarkblue, and Aurora), amendment-mulch [“compost + sawdust” (included preplant amendment and a surface mulch of either an agricultural on-farm crop waste compost or yard-debris compost and sawdust), and “weed mat” (no preplant amendments but with a sawdust mulch topped with weed mat)]. Adding on-farm compost as a preplant amendment and as part of the mulching program increased soil pH from 4.9 to 6.9, organic matter content (OM), and calcium (Ca), magnesium (Mg), and potassium (K) levels compared with the weed mat treatment. The reduced plant growth and yield in some cultivars grown in the compost + sawdust treatment was likely due to the higher soil pH. ‘Bluegold’ and ‘Draper’ were among the cultivars with consistently high flower bud set (40% to 57%), whereas others had consistently low values (e.g., 22% to 45% in ‘Bluecrop’). The number of flowers per bud was affected only by cultivar. There was no effect of year or amendment-mulch treatment on percent fruit set which averaged 93% during the study; however, ‘Ozarkblue’ had a significantly lower fruit set (88%) than only ‘Aurora’ (96%). Berry weight was affected by year (plant age), cultivar, and amendment-mulch treatment. ‘Ozarkblue’ produced the largest berries. Type of amendment-mulch had little effect on berry weight, except in ‘Ozarkblue’, ‘Aurora’, and ‘Reka’ where plants grown with weed mat produced larger fruit than those grown with compost + sawdust. On average, ‘Bluejay’, ‘Draper’, and ‘Liberty’ fruit had the highest percent soluble solids (TSS) and ‘Ozarkblue’ the lowest. Fruit harvested from plants grown with weed mat were firmer than when compost + sawdust was used. ‘Draper’ fruit were much firmer than those of the other cultivars in all years of the study. The number of flower buds per plant multiplied by the number of flowers/bud and berry weight (cultivar specific) and average fruit set was a good predictor of yield in young plants. Yield per plant increased from the second through seventh growing seasons as plants matured in all cultivars except for ‘Duke’ which had the greatest yield in 2014. Cumulative yield was highest in ‘Legacy’ and lowest in ‘Bluejay’ and in ‘Draper’, which had relatively low yield when plants were young. Most cultivars had greater yield when grown with weed mat, whereas ‘Bluegold’ and ‘Liberty’ were unaffected by amendment-mulch treatment. Because weeds were managed in all plots, the cultivar response to amendment-mulch was likely a reflection of sensitivity to preplant amendment with on-farm compost and the resulting higher soil pH. It is possible that the cultivars differed in their adaptability to the various fertility regimes caused by the amendment-mulch treatments and fertilizers used in our study.

Effects of plastic mulch on the radiative and thermal conditions and potato growth under drip irrigation in arid Northwest China

Drip irrigation and plastic-film mulch are useful water-saving tools for potato (Solanum tuberosum L.) production in arid Northwest China. Effects of the radiative and thermal conditions produced by the plastic-film mulch on potato growth can be positive or negative. The objective of this study is to know how radiative and thermal conditions and potato growth are affected by the two most commonly used plastic-film mulches (transparent and black) to efficiently use the positive effects of the plastic-film mulch. Field experiments were conducted at the experimental station located in Wuwei, Gansu Province to explore the effects of transparent mulch (TM), a non-mulched check (NM), and black mulch (BM) on the net radiation (Rn), soil heat flux (G), soil temperature, and potato growth under surface drip irrigation during different plant development stages in 2014 and 2015. Results indicated that the daily integral Rn in the BM treatment was greater than in the TM treatment, while the amplitude of G in the BM treatment was lower than in the TM treatment. The BM treatment had 3.0 and 3.9°C greater maximum mulch surface temperature than the TM treatment and had greater longwave radiation on the canopy emitted from the mulch surface. The differences in Rn, G, and soil temperature among the treatments diminished with plant canopy enlargement. The potato plant height rankings were BM>TM>NM. The BM treatment had 26% higher jumbo plus large tuber yield than the TM treatment in 2014. Compared with the BM treatment, the TM treatment had the similar potato yield but 9% and 8% less evapotranspiration in 2014 and 2015. The results suggested that the black plastic-film mulch was more suitable for large potato tuber production, while the transparent plastic-film mulch was favorable for water-saving.