Soil surface evaporation processes under mulches of different sized gravel

To reduce water loss from soil surface evaporation is important in agricultural and environmental practices, especially in arid and semi-arid regions. Gravel mulch has long been practiced to reduce soil surface evaporation. In this study, a series of simulation experiments were conducted to study the effects of gravel mulches of different sizes on evaporation process from soil surface. Four mulch treatment levels were used: diameter 0.5 cm (A), diameter 2.5 cm (B), diameter 4.5 cm (C), and bare soil (CK), with three replicates. It was found that the gravel mulches dramatically reduced the evaporation from bare soil surface, particularly when soil water contents were at high levels. Under the same soil water content, the evaporation reduction rates under gravel mulches were negatively correlated with gravel sizes. The evaporation processes under gravel mulches were much more stable as compared with that from bare soil surface. The ratio of the soil surface evaporation to the atmospheric evaporation (E_ss/E_sa) and soil water contents with no mulch decreased rapidly with time. Soil water contents decreased slowly with time under mulches while the E_ss/E_sa values maintained at the more or less stable levels. During the successive evaporation process of 41 days, the cumulative soil surface evaporation under mulches was linearly correlated with time but that from bare soil surface was logarithmically correlated with time.     

Photosynthesis,growth, and fruit yield of cucumber in response to oxo-degradable plastic mulches

The use of plastic mulch is associated with a higher increase in yield of vegetables. However, at the end of the growing season for each crop, plastic mulching can create environmental pollution that can cause negative impacts on the environment that could be solved by the use of degradable plastics. The aim of this study was to determine the effect of oxo-degradable plastic mulches on soil temperature, growth, gas exchange, and cucumber crop yield. The study was conducted in two locations in the northeast of Mexico during the spring and summer of 2013. The plastic mulch colors with additives were blue, green, and red and each color having 8% and 12% of pigment and 22% and 23% of Titanium dioxide (Rutile). The resultant treatments were compared with the black plastic mulch, which is the standard plastic in the world, and bare soil in a randomized complete block design with three replications in two locations. The mean soil temperature at both locations was statistically higher in black plastic mulch, followed by the oxo-degradable plastics mulches and lowest in the control. Gas exchange was not affected by plastic mulches. SPAD units as the index of chlorophyll content in leaves were very little affected by plastic mulch. Both, commercial and total yield were statistically similar in the oxo-degradable plastic mulches and the black plastic mulch, and lowest in the control. Plastics with higher concentrations of pigment registered higher degradation in both locations. Our results suggest that different plastic mulches impact positively on the yield of cucumber crop. The benefit in yield by the different plastic mulches in the conditions of this study was due to their soil warming ability that results in improved soil temperature, leaf area, and plant dry weight.     

A preliminary watershed scale soil quality assessment in north central Iowa, USA

Soil quality assessment has been recognized as an important step toward understanding the long-term effects of conservation practices within agricultural watersheds. Our objective was to assess soil quality within the South Fork watershed of the Iowa River using various indicators and assessment approaches. Soil samples were collected during 2003 and 2004 from 29 areas of 32 ha (80 acres) each along two transects traversing the watershed. Soil pH, Mehlich III extractable P, K, Ca and Mg, electrical conductivity (EC), total organic carbon (TOC), and total N (TN) were measured. The Soil Management Assessment Framework (SMAF) was used to compute a soil quality index (SQI), while soil loss, the soil tillage intensity rating (STIR), N-leaching potential, and soil conditioning index (SCI) were determined for each sampling area using the 2003 version of the Revised Soil Loss Equation (RUSLE2). Overall, there were no soil fertility limitations within the watershed based on an average pH of 6.96 and extractable P and K levels of 36 and 162 mg kg⁻¹, respectively. Soil loss, STIR, N-leaching, and SCI averaged 1.13 Mg ha⁻¹, 68, 3, and 0.4, respectively. The SMAF analysis indicated soils within the watershed were functioning at 87% of their full potential. The lowest indicator score was associated with TOC (0.60) because the average value was only 28.4 g kg⁻¹. The SCI and SQI indices were positively correlated although since it used measured data, the SMAF appears to provide more information about the effects of management practices within the watershed. Soils in upper landscape positions had lower TOC and C:N ratios indicating an increased risks for both erosion and for nitrate leaching. Management of soils on hilltops may be the most effective way to minimize N and P losses within the watershed.     

Long term tillage,cover crop,and fertilization effects on microbial community structure,activity: Implications for soil quality

Conservation agriculture practices, such as reduced tillage, cover crops and fertilization, are often associated with greater microbial biomass and activity that are linked to improvements in soil quality. This study characterized the impact of long term (31 years) tillage (till and no-till), cover crops (Hairy vetch- Vicia villosa and winter wheat- Triticum aestivum, and a no cover control), and N-rates (0, 34, 67 and 101 kg N ha⁻¹) on soil microbial community structure, activity and resultant soil quality calculated using the soil management assessment framework (SMAF) scoring index under continuous cotton (Gossypium hirsutum) production on a Lexington silt loam in West Tennessee.No-till treatments were characterized by a significantly greater (P < 0.05) abundance of Gram positive bacteria, actinomycetes and mycorrhizae fungi fatty acid methyl ester (FAME) biomarkers compared to till. Saprophytic fungal FAME biomarkers were significantly less abundant (P < 0.05) under no-till treatments resulting in a lower fungi to bacteria (F:B) ratio. Key enzymes associated with C, N & P cycling (β-glucosidase, β-glucosaminidase, and phosphodiesterase) had significantly higher rates under no-till relative to till, corresponding to significantly greater (P < 0.05) soil C and N, extractable nutrients (P, K and Ca) and yields. Mycorrhizae fungi biomarkers significantly decreased (P < 0.05) with increasing N-rate and was significantly less (P < 0.05) under the vetch cover crop compared to wheat and no cover. Treatments under vetch also had significantly higher β-glucosaminidase and basal microbial respiration rates compared to wheat and no cover.Consequently, the total organic carbon (TOC) and β-glucosidase SMAF quality scores were significantly greater under no-till compared to till and under the vetch compared to wheat and no cover treatments, resulting in a significantly greater overall soil quality index (SQI).Our results demonstrate that long-term no-till and use of cover crops under a low biomass monoculture crop production system like cotton results in significant shifts in the microbial community structure, activity, and conditions that favor C, N and P cycling compared to those under conventional tillage practices. These practices also led to increased yields and improved soil quality with no-till having 13% greater yields than till and treatments under vetch having 5% increase in soil quality compared to no cover and wheat.     

Colored plastic mulches affect soil temperature and tuber production of potato

Abstract

The main crops on which plastic mulch is widely used in Mexico include tomato, bell pepper, eggplant, melons, watermelons, and strawberry; however, very little research has been performed on potato. One of the main benefits associated with plastic mulching is the modification of the microclimate around the plant. To obtain a positive microclimate modification studies are required to understand how plastic mulch affects growth and yield of a given species. Previous field research assessing the response to colored plastic mulching in potato shows no consistent results on yield, maybe because it has been performed under different geographical latitudes. Potato in Mexico is conventionally cultivated on bare soil combined with various irrigation systems. The objective of the present study was to examine the effect of colored plastic mulches on soil temperature, growth, yield and photosynthetic response of potato plants. The experiment was conducted in Northeast Mexico and the treatments included were: black plastic mulch (BPM); white-on-black plastic mulch (W/B), silver-on-black (SPM), aluminum-on-black plastic mulch (APM) and a control that consisted of bare soil cultivated plants. Treatments were arranged in a randomized complete block design with four replications. Results suggest that average daily mean soil temperature was linearly and negatively correlated with total yield and yield of first-quality tubers. Total yield and yield of first-quality tubers of plants mulched with W/B, SPM and APM was significantly higher (p≤0.05) than those of control plants. Leaf area and shoot dry weight were increased when soil temperatures were higher due to the effect of radiation transmission to the soil, however, this decrease was associated with a decrease in tuber production. The results of our study indicate that plants grown under BPM, which induced the highest soil temperature, showed marginal difference in yield compared with control plants, suggesting that colored plastic mulches have a positive effect on yield through decreased rise in soil temperature.     

Effect of organic mulches on soil bacterial communities one year after application

The application of organic mulches as a soil cover is effective in improving the quality of soil. However, very little information is available on the effect of mulches on the soil microbial community. In this study, we investigated the effect of various organic mulches on soil dehydrogenase activity (DHA) and microbial community structures in the top 1 cm and 5 cm below the soil surface 1 year after application of the mulches. DHA was stimulated at both depths in plots mulched with grass clippings (GC), but was not significantly different from the control for the other mulch treatments. Fatty acid methyl ester (FAME) analysis and denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction-amplified 16S rDNA fragments were used to assess changes in the soil microbial community structure. Cluster analysis and principle component analysis of FAME profiles showed that only soil mulched with pine chips distinctively clustered from the other treatments. At the soil surface, bacterial DGGE profiles revealed that distinct shifts in several bacterial populations occurred in soils mulched with GC and eucalyptus yardwaste (EY), while DGGE profiles from soil at the 5 cm depth revealed no distinct changes. Changes in bacterial diversity at the soil surface under different mulches were calculated based on the number of bands in the DGGE profile using the Shannon-Weaver index of diversity ( H). Compared to the control ( H =0.9), the GC- and EY-treated soils showed slightly increased bacterial diversity, with an H of 1.1 and 1.0, respectively. These results indicate that the long-term effect of organic mulches on the soil microbial activity and community structure is highly dependent upon the type of mulch and is mostly exerted in the top few centimeters of the soil profile.     

Changes induced by plastic film mulches on soil temperature and their relevance in growth and fruit yield of pickling cucumber

Purpose: The aim of this study was to realize whether soil mulching, with different plastic mulch colors, is a suitable practice for the culture of pickling cucumber.

Materials and Methods: The crop was cultured or not with black, silver/black, white/black, and aluminum/black plastic films, treatments were evaluated in randomized complete block design, to determine their effect on soil temperature, gas exchange, nutrient concentration, growth, and fruit yield.

Results and Conclusions: Black, silver/black, and aluminum/black plastic mulches were higher (p?≤?0.05) in plant height, leaf area, and shoot dry weight than bare soil at 15 days after sowing, whose results were similar than using white/black film. Maximum, minimum, and mean soil temperatures were higher with all plastic mulches except for aluminum/black, in which the maximum soil temperature was similar to the one in bare soil. There was no difference in net photosynthesis and there was very little difference in nutrient concentration between plants in plastic mulches and plants in bare soil; however, early and total yield showed a higher (p?≤?0.05) yield in all plastic mulches, and lower with bare soil and white/black plastic mulch. Our results confirm that soil mulching impacts the pickling cucumber yield. We suggest a carefull selection of the color plastic mulch.     

Evaluation of different mulch materials for reducing soil surface evaporation in semi‐arid region

In recent years, the use of new mulches for soil water conservation in arid regions has been introduced as an alternative to conventional (plastic) mulches. However, systematic studies concerning the effects of different organic [pistachio shell mulch (PSM), wheat straw mulch, de‐oiled olive pomace mulch (DOM) or wood chips mulch], chemical [superabsorbent polymer (HM) or organic‐based emulsion polymer (PEM)] and mineral [gravel mulch (GM)] covers on soil and water conservation are scarce. Therefore, two experiments were carried out. Experiment 1 was aimed at evaluating the effects of mulches of different composition on soil surface evaporation, whereas in experiment 2 we investigated the effects of this decrease in soil evaporation due to different mulch materials on some olive tree physiological responses to soil drying. We analysed stem water potential, transpiration rate, stomatal conductance, leaf density and maximum efficiency of photosystem II photochemistry (Fv/Fm) of 2‐yr‐old plants of ‘Konservalia’ olive, grown in pots in open field. The results showed that different mulch materials had different efficiency on soil water conservation and DOM and pistachio shell mulch PSM – as new mulch materials – seems more favourable for conserving soil water. Water stress caused reductions in all parameters measured and increment in leaf density compared with unstressed treatment. Olive plants grown using different soil mulch presented higher values of stem water potential, transpiration rate, stomatal conductance and Fv/Fm ratio compared to control plants. Although all the mulch treatments improved the water content of soil, DOM and PSM were found to be superior in maintaining optimum soil water content for olive use.     

新疆地区全生物降解膜降解特征及其对棉花产量的影响

针对残膜污染已经成为新疆棉田最严重的生态环境问题,以广东上九公司提供的3种淀粉基全生物降解地膜为供试材料,在我国西北内陆棉区（新疆石河子）开展了田间试验评价研究。结果表明,由于配方的不同,3种降解膜的降解特性、增温保墒性能以及对棉花产量的影响存在显著的差异性。从地表覆盖试验与填埋试验的结果看,与日本的生物降解地膜（CK2）相比,国内的3种供试地膜品种都表现为降解过快,特别是A膜和B膜,降解最为迅速,C膜降解相对较慢。过快的降解速率显著地影响了3种供试降解膜的增温保墒性能,特别是A膜和B膜,与普通膜（CK1）相比,土壤温度平均低2～3℃,土壤水分低3～5个百分点,3种供试降解膜比较,C膜的增温保墒效果略好。从产量结果来看,与普通膜相比,国内供试的A膜和B膜对产量影响较大,减产幅度分别为20%以上,供试C膜和对照的日本降解膜都表现为增产趋势,但与普通膜产量结果比较差异并不显著。     

不同地面覆盖对土壤性状和秋播大蒜产量及品质的影响

为探究秋播大蒜适宜的地面覆盖类型及其对大蒜产量的影响机制,从而为地面覆盖在大蒜高产高效栽培中的应用提供理论依据,以'麻江红蒜'为试验材料,以不覆盖处理为对照,分别设置白色地膜、黑色地膜、银灰色地膜、1～2cm和3～4cm稻草、1～2cm和3～4 cm稻壳共7种地面覆盖处理,分析不同处理对土壤含水量、温度和酶活性以及大蒜...     

Effects of Mulching Blueberry Plants With Cranberry Fruits and Leaves On Yield,Nutrient Uptake and Weed Suppression

Integration of local organic wastes as mulches into farm production can provide waste management options and an alternative to landfilling. In 2000, cranberry growers needed ways to dispose of excess cranberries caused by overproduction and a federal regulation limiting the fruit's marketable production. This study examined the use of excess cranberry fruits and leaves as mulches on established blueberry plants. The objective of this study was to determine the effects of these novel mulches on established blueberry plant nutrient uptake, fruit yield, selected soil chemical properties and weed suppression. A randomized block design was set up and maintained for two years with four different mulch treatments (no mulch, 5.1cm cranberry fruit, 10.2-cm cranberry fruit and 10.2-cm cranberry leaves). Leaf tissue nutrients (N, P, K, Ca, Mg, Mn, Fe, Cu, Zn, S, B, Al), fruit yield and average fruit size, selected soil properties, weed biomass and number of weed types were determined. In the second year, the fruit yield in the mulched treatments was lower than in the control (P<0.05), but not the fruit size. One possible reason is a significant decrease in leaf nitrogen uptake observed in some mulch plots. Weed biomass was significantly reduced along with species diversity. This study shows that novel mulches need to be carefully evaluated before being used due to their potential environmental and plant impacts.     

Effects of gravel on grassland soil carbon and nitrogen in the arid regions of the Tibetan Plateau

Many previous studies have focused on soil gravel concentrations and their effect on crop yields in agricultural systems. The extent of carbon and nitrogen sequestration in soils under steppe systems in relation to surface gravel mulch remains largely unexplored. This study investigated the effects of gravel mulches on soil organic carbon and total nitrogen stocks in the arid and windy regions of the Tibetan Plateau. Surface gravel mulches provide a more favorable environment for soil carbon and nitrogen stocks than do non-mulched sites. Soil organic carbon and total nitrogen stocks were highest (46.9 Mg ha^− 1 SOC and 2.8 Mg ha^− 1 TN) in the medium gravel mulch sites with ~ 40-50% gravel, and lowest (29.5 Mg ha^− 1 SOC and 1.4 Mg ha^− 1 TN) in no gravel mulch sites. Analysis of aggregate size fractions indicated that the vast majority of SOC was present in microaggregate fractions throughout the top 30 cm of soil. Considering the low level of soil disturbance in the study area, the carbon contained in the macroaggregate fraction might become stabilized in the soil. Gravel mulches above the soil surface have an important bearing on soil carbon sequestration as they control wind erosion, decrease soil surface evaporation and change soil physical behavior in the arid and semiarid regions.     

Agronomic performances of biodegradable and non-biodegradable plastic film mulching on a maize cropping system in the semi-arid Loess Plateau, China

Biodegradable plastic film mulch (PFM) is considered an alternative to non-biodegradable PFM to mitigate the negative impacts of residual film.However,the agronomic performance of biodegradable PFM in comparison to non-biodegradable PFM still needs to be tested.In this study,we evaluated the effects of biodegradable and non-biodegradable PFM on soil physicochemical properties,microbial community,and enzyme activities,as well as maize growth performance.Biodegradable and non-biodegradable PFM bot...     

Long-term soil management effects on crop yields and soil quality in a dryland Alfisol

A long-term experiment was conducted with the objective of selecting the appropriate land management treatments and to identify the key indicators of soil quality for dryland semi-arid tropical Alfisols. The experiment was conducted using a strip split–split plot design on an Alfisol (Typic Haplustalf) in southern India under sorghum (Sorghum vulgare (L))-castor (Ricinus communis (L)) bean rotation. The strip constituted two tillage treatments: conventional tillage (CT) and minimum tillage (MT); main plots were three residues treatments: sorghum stover (SS), gliricidia loppings (GL), ‘no’ residue (NR) and sub plots were four nitrogen levels: 0 (N₀), 30 (N₃₀), 60 (N₆₀), and 90 kg ha⁻¹ (N₉₀). Soil samples were collected after the sixth and seventh year of experimentation and were analyzed for physical, chemical and biological parameters. Sustainable yield index (SYI) based on long-term yield data and soil quality index (SQI) using principal component analysis (PCA) and linear scoring functions were calculated. Application of gliricidia loppings proved superior to sorghum stover and no residue treatments in maintaining higher SQI values. Further, increasing N levels also helped in maintaining higher SQI. Among the 24 treatments, the SQI ranged from 0.90 to 1.27. The highest SQI was obtained in CTGLN₉₀ (1.27) followed by CTGLN₆₀ (1.19) and MTSSN₉₀ (1.18), while the lowest was under MTNRN₃₀ (0.90) followed by MTNRN₀ (0.94), indicating relatively less aggradative effects. The application of 90 kg N ha⁻¹ under minimum tillage even without applying any residue (MTNRN₉₀) proved quite effective in maintaining soil quality index as high as 1.10. The key indicators, which contributed considerably towards SQI, were available N, K, S, microbial biomass carbon (MBC) and hydraulic conductivity (HC). On average, the order of relative contribution of these indicators towards SQI was: available N (32%), MBC (31%), available K (17%), HC (16%), and S (4%). Among the various treatments, CTGLN₉₀ not only had the highest SQI, but also the most promising from the viewpoint of sustainability, maintaining higher average yield levels under sorghum–castor rotation. From the view point of SYI, CT approach remained superior to MT. To maintain the yield as well as soil quality in Alfisols, primary tillage along with organic residue and nitrogen application are needed.     

覆盖稻草及加盖薄膜对免耕马铃薯农艺性状及品质的影响

研究了覆盖不同厚度稻草（4、8 cm）以及加盖普通地膜和黑色地膜对免耕马铃薯农艺性状及品质的影响。结果表明：覆盖不同厚度稻草的影响效果具有显著的差异,与覆盖稻草4 cm相比,覆盖稻草8 cm可提高单株结薯数和产量,降低绿薯率,但降低出苗率和株数,其他品质参数差异不明显;在覆盖稻草4 cm的基础上加盖薄膜具有提高单薯重和产量的作用,但在覆盖稻草8 cm的基础上加盖薄膜则对出苗不利,降低了出苗率和株数,降低产量;加盖地膜能显著降低绿薯率,其中黑色地膜的效果优于普通地膜。     

黄土高原旱地土壤质量评价指标研究

基于设置在陇中黄土高原半干旱区的长期定位试验,运用综合评价模型,定量评价了小麦→豌豆双序列轮作系统6种不同耕作方式对土壤质量的影响。结果表明,采用加权综合法和加乘法则对土壤质量进行综合评价,能够较好地反映土壤质量的实际情况,敏感地反映耕作方式对土壤质量的影响。运用逐步判别分析法对6种不同耕作方式[传统耕作(T)、免耕作(NT)、传统耕作秸秆还田(TS)、免耕秸秆覆盖(NTS)、传统耕作地膜覆盖(TP)、免耕地膜覆盖(NTP)]下29项土壤属性指标进行筛选,建立了包括团粒结构、全氮、速效氮、有机质、蔗糖酶活性、作物产量、种植纯收益和产投比8项因子的简化评价指标体系。原始评价指标体系下2种轮作序列土壤质量指数排序均为NTSTSNTPNTTPT;简化评价指标体系下豌豆→小麦轮作序列土壤质量指数排序为NTSTSNTPNTTTP,而小麦→豌豆轮作序列土壤质量指数排序为NTSTSNTNTPTTP。进一步相关分析和方差分析表明,应用逐步判别分析法建立的简化指标体系具有较高的代表性,可适用于黄土高原半干旱区土壤质量评价。     

对板栗园树盘土壤双重覆盖的效应研究

对板栗园树盘土壤进行麦秸、黑色地膜和无色地膜的单一或双重覆盖试验。结果表明，所有覆盖处理的保水效果均好于对照，但对温度的影响因不同处理而有差异；覆草＋覆膜的处理不仅具有显著的增温保墒作用，能培肥地力，双重覆盖处理的有机质平均含量比单独的膜覆盖增加0.1%，有效磷和有效钾分别提高1.2和5.7 mg·kg^-1，孔隙度增加3.21%，栗果产量增加10.70%。综合各种效应不同处理优劣顺序为：黑膜+草>无色膜+草>覆草> 黑膜>无色膜>对照。     

Double mulching improves soil properties and productivity of maize-based cropping system in eastern Indian Himalayas

A field experiment was conducted for two consecutive years at North Eastern Indian Himalayan region to assess the effect of soil moisture conservation measures on soil and water productivity of different rainfed maize (Zea mays L.) - based cropping sequences. Results revealed that double mulching with in-situ maize stover mulch (MSM) + fresh biomass of white hoary pea (WHP-Tephrosia candida) and MSM + fresh biomass of ragweed (RW- Ambrosia artemisiifolia) improved soil moisture content (SMC) and leaf relative water content of crops during dry season. The soil organic carbon (SOC) content and stocks under MSM + WHP and MSM + RW mulches were significantly higher than that under no mulch at 0–15 cm depth. The soil microbial biomass carbon and dehydrogenase activity were maximum under MSM + WHP/RW. The highest system productivity was obtained from maize-French bean (Pole type-PT) sequence under MSM + RW followed by MSM + WHP. The water productivity was the highest under MSM + WHP. While SOC content was the highest under maize-French bean (PT), the maximum plant available nitrogen and phosphorus were obtained under maize-black gram sequence.Thus, double mulching technology involving MSM and RW (available in plenty) is a viable option for improving soil, crop and water productivity under rainfed hill ecosystems of eastern Indian Himalayas.     

The positive relationship between soil quality and crop production: A case study on the effect of farm compost application

In order to ensure sustainable agriculture, and for evaluating the effects of management practices on soil processes, tools for assessing soil quality are required. The development and use of a multiparameter index, which includes a wide range of soil properties, have been tested and found useful by several studies. However, soil quality measurements are ‘stand-alone’ tools unless they are either linked to important soil functions, used to characterize (agro)ecosystems or used to predict sustainability or productivity. In our study, the relationship between crop production and soil quality was assessed in a six year old field experiment studying the effect of farm compost (FC) amendment in a crop rotation of potato, fodder beet, forage maize and Brussels sprouts. To justify the hypothesis that repeated FC amendment results in both improved soil quality and consequently higher crop yields, a wide range of chemical, biological and physical soil properties were measured and integrated into a soil quality index (SQI). Next, crop yields were used as a functional goal to verify the causal relationship between SQI and crop production. Our results showed that there were significant changes in chemical, physical and biological soil quality as a result of repeated FC amendment. This was evidenced for example by a remarkable increase in both soil organic carbon (SOC) and total N content. Microbial biomass, the relative amount of bacterivorous nematodes and earthworm number were significantly increased as well and, together with SOC and total N, indicated as the dominant factors in assessing soil quality. The integration of these key indicators into the SQI revealed higher SQI values when FC was applied. In addition, crop yields were increased in all FC treated plots by which SOC was pointed out as the most important indicator influencing crop production. Finally, a causal relationship was observed between soil quality and the yield of potato and fodder beet. We conclude that our SQI may be a promising and useful tool to compare different (soil) management practices in relation to a strategic, regional goal, e.g., sustainable high yields. Before generalizing, we recommend a thorough validation of our SQI in other long-term field experiments.     

Weed-control effects on different types of cover-crop mulches

Abstract

A field experiment was conducted during the period 2002–2006 at the Experimental Farm in Zawady, located in the mid-eastern part of Poland, to evaluate the effect of date of mulch ploughing down (autumn, spring, left till cabbage harvest) and the plant mulches [phacelia (Phacelia tanacetifolia Benth.), vetch (Vicia sativa L.), serradella (Ornithopus sativus), and oat (Avena sativa L.)] on the weed pressure in red cabbage (Brassica oleracea L. var. capitata L. f. rubra) in the first and onion (Allium cepa L. var. cepa Helm.) in the second year after mulching. The biomass yield of plant mulches, total cabbage and onion yields, and biomass and number of weeds before planting and harvest of cabbage and before sowing and harvest of onion were assessed. Weed infestation was determined by the quantitative-weighting method. The biomass yields of phacelia and oat amounted to 26.6 and 24.8 t·ha^?1, respectively, and were almost 2.5-times higher than biomass yields of serradella and vetch. The average cabbage and onion yields were 45.8 and 41.9 t·ha^?1, respectively. The yields of vegetables following mulches were higher than the yields recorded in the unmulched control. The weed species most often found in the experiment were Viola arvensis Murr., Capsella bursa pastoris, Matricaria indora L., Chenopodium album L., and Stellaria media (L.) Vill. Of the examined dates of mulch ploughing down, the spring-incorporated mulches were most effective in reducing the number of weeds in cabbage whereas the nonincorporated mulches showed such an effect in onion. Nonlegumes (phacelia and oat) used as mulch produced higher fresh biomass yields than did vetch and serradella. Oat and phacelia mulches significantly reduced the fresh biomass and number of weeds before cabbage planting. Additionally, oat mulch reduced the fresh biomass of weeds before cabbage harvest. Also, oat and phacelia mulches reduced the number of weeds before onion harvest.