Combinations Of Cover Crops Research Articles

Soil Ecoenzymatic Stoichiometry Reveals Microbial Metabolic Limitations in Apple Orchards with Cover Crop and Organic Fertilizer Incorporation

Understanding the stoichiometry of extracellular enzymes in soil, particularly in relation to nutrient acquisition (e.g., carbon, nitrogen, phosphorus), provides valuable insights into microorganisms’ resource requirements. This study investigates the metabolic constraints of soil microorganisms in response to different growth stages of apple trees under various soil management practices. A 14-year long-term experiment with a split-plot design was conducted, where the main plots received different cover crop treatments (bare vs. cover crop), and subplots were subjected to four fertilizer treatments (CK, M, NPK, MNPK). The significant main and interactive effects of cover crops, fertilizer treatment, and growth period on soil nutrients were observed (p < 0.001). Both cover crop and fertilizer treatments significantly increased the soil organic matter content, with implications for orchard resilience to drought. However, the cover factor alone did not notably influence soil carbon–nitrogen ratios or microbial communities. Microbial carbon limitations were driven by soil water dynamics and microbial biomass, while microbial phosphorus limitations were closely linked to total nitrogen levels. The results underscore the combination of cover crops and MNPK fertilizer-enhanced soil nutrient levels and enzyme activities, mitigating microbial carbon and phosphorus limitations. These findings suggest practical strategies for optimizing fertilization practices to improve soil fertility and address nutrient constraints in orchard ecosystems.

Comparison of cover crop termination methods for small-scale organic vegetable production: effect on soil fertility and health

Termination methods and the timing of the termination of the cover crops are critical factors determining the efficacy of cover crops in improving soil fertility and quality. We hypothesized that different termination methods will produce varying quantities of organic residue which will affect microbial diversity and thereby nutrient cycling and availability. The objective of this study was to compare termination methods (roller-crimper, flail mowing, rotary mowing, sickle bar mowing, and occultation using black tarps) for fall-grown cover crop combination (hairy vetch-cereal rye) under organic vegetable production. Field experiments were carried out in three consecutive years (2018–2021) and soil samples were collected from 0 to 15 cm and processed for analysis. Soil organic matter content, nutrients, health parameters, enzymes, and microbial diversity were measured. Flail mowing significantly enhanced the potentially mineralizable nitrogen, available phosphorus, and active carbon. Total Phospholipid Fatty Acid (PLFA) analysis showed a 24% increase for flail mowed, 17% for rotary mowed, and 15% for sickle bar mowed termination methods. There was a significant increase in active carbon content which ranged from 38.9% (rotary mowed), 25.4% (sickle bar mowed), 23.5% (flail mowed), 16.4% for crimper rolled method, and with 2.8% (occultation) respectively. Individual termination methods had varying effects on select enzyme activities. Results indicated that integrating cover crops has the potential to modify soil microbial community structure and increase soil enzyme activities. In this study, flail mowing appeared to be a good method for managing cover crops of choice in terms of soil microbial functionality and fertility.

Long term influence of alternative corn cropping practices and corn-hay rotations on soil health, yields and forage quality

Modifications to continuous corn production systems can reduce environmental impacts and soil degradation, yet the social viability of these modifications is linked to the degree to which they also influence yields and crop quality. In this study, we focus on forage production systems and evaluate how yields, crop quality, soil health indicators, and associated ecosystem services are influenced by corn-hay rotation treatments, cover cropping, and tillage reduction in silage production using a unique 10-year dataset from Borderview Research Farm in Vermont, United States. Physical, chemical, and biological soil health indicators were monitored annually alongside yields and crop quality in a randomized complete block design experiment. We use a mixed model analysis of variance approach to demonstrate significant influences of time and treatments on yields, crop quality and soil health parameters (at p < 0.05). The winter rye cover crop treatment had no significant influence in this study. No-till significantly increased aggregate stability and had no significant effect on other metrics. When cover crop and no-till were combined, they significantly increased soil organic matter content, respiration and aggregate stability. The cover crop, no-till, and no-till cover crop combination treatments had no significant effect on yields or forage quality, suggesting these conservation practices can be adopted without sacrificing yields. Our study also found that corn-hay rotations can significantly increase soil organic matter, respiration, aggregate stability, and crude protein content compared to continuous corn, but they can negatively influence active carbon, total dry matter yield and digestibility. The length of rotation influences the degree to which corn-hay rotations maintain or reduce yields when compared to continuous corn. Shorter rotations of perennial forages (4 years of hay, 6 years of corn) can sustain dry matter yields that are not significantly different from continuous corn, but longer perennial forage rotations (8 years of hay, 2 years of corn) will significantly reduce overall dry matter yields. Among the treatments, no-till in combination with cover cropping in corn silage fields, and a rotation of 4 years of hay to 6 years of corn are likely to achieve the greatest overall benefits in forage production systems.

Sustainable agricultural practices to improve soil quality and productivity of soybean and upland rice

Combining cover crops with multifunctional microorganisms provides significant increments in the grain productivity of soybean and upland rice crops. However, there are still few studies that aimed to evaluate the effect of this combination on the productivity of agricultural systems. The objective of this study was to determine the effect of the mix of cover crops and the co-inoculation of multifunctional rhizobacteria on the quality of the soil, yield components, and on the grain yield of soybean and upland rice. The experimental design was in random blocks with 24 treatments in a 6x2x2 factorial scheme. Treatments were the combination of 6 (5 mix of cover crops (mixture of seeds of different cover crops species) and the control (fallow), 2 (upland rice and soybeans), 2 (co-inoculated (inoculation with two microorganisms) or not (no microorganisms), with four replications. Combination of cover crops provided an increase in Ca and Mn levels in the soil, increased activity of soil quality indicator enzymes (phosphatase and arylsulfatase), higher soybean yield, and higher number of upland rice panicles. The co-inoculation with multifunctional rhizobacteria led to an increase in phosphorus levels in the soil, the number of pods per plant, the mass of 100 grains for soybean cultivation, the number of grains per panicle, and productivity of upland rice. Therefore, a mix of cover crops, combined with the co-inoculation with multifunctional rhizobacteria are sustainable agricultural practices that can contribute to the improvement of soil quality and the increase of the productivity of soybean and upland rice crops

The Effects of Soil Improving Cropping Systems (SICS) on Soil Erosion and Soil Organic Carbon Stocks across Europe: A Simulation Study

Healthy soils are fundamental for sustainable agriculture. Soil Improving Cropping Systems (SICS) aim to make land use and food production more sustainable. To evaluate the effect of SICS at EU scale, a modelling approach was taken. This study simulated the effects of SICS on two principal indicators of soil health (Soil Organic Carbon stocks) and land degradation (soil erosion) across Europe using the spatially explicit PESERA model. Four scenarios with varying levels and combinations of cover crops, mulching, soil compaction alleviation and minimum tillage were implemented and simulated until 2050. Results showed that while in the scenario without SICS, erosion slightly increased on average across Europe, it significantly decreased in the scenario with the highest level of SICS applied, especially in the cropping areas in the central European Loess Belt. Regarding SOC stocks, the simulations show a substantial decrease for the scenario without SICS and a slight overall decrease for the medium level scenario and the scenario with a mix of high, medium and no SICS. The scenario with a high level of SICS implementation showed an overall increase in SOC stocks across Europe. Potential future improvements include incorporating dynamic land use, climate change and an optimal spatial allocation of SICS.

Cover crops and carbon stocks: How under-vine management influences SOC inputs and turnover in two vineyards

There is a growing awareness surrounding the importance of maintaining and increasing soil organic carbon (SOC, henceforth) stocks in vineyard systems. Increasing SOC positively influences numerous soil properties and has the added advantage of removing atmospheric CO2, thereby helping to mitigate the effects of climate change. Cover crops have long been used to influence soil properties in vineyard mid-rows, including increasing SOC content. Few studies, however, have quantified cover crop influence on SOC stocks and composition in the under-vine area, owing to a general reluctance to adopt under-vine cover crop management. This research aims to quantify SOC stocks and dissolved organic carbon (DOC) in soils from four treatments of under-vine management practice including two cover crop combinations, a straw mulch and herbicide-managed control across two vineyard sites established in 2014. We sampled soils under-vine to depths of 0–30 cm (stratified; 0–10 cm and 10–30 cm) and quantified both SOC concentrations and bulk density to ascertain SOC stocks. Further to this, we quantified water extractable organic carbon (WEOC) as a measure of the labile carbon stock, and measured heterotrophic respiration in a laboratory incubation as an indication of SOC turnover. We found that cover crop-managed soil under-vine sequesters up to 23% more soil organic carbon (SOC) as the traditional, herbicide practice over a five-year period of growth. Microbial activity increased by more than double in cover crop soils, owing to an increase in DOC and that there is evidence for more resistant C in cover crop soils. These results suggest that cover crop management under-vine is a viable solution to increase SOC stocks within vineyard systems. Taken together, the results of this study indicate that a shift from bare earth to cover crops in the under-vine region has the potential to sequester carbon in vineyard soils.

Single- versus Double-Species Cover Crop Effects on Soil Health and Yield in Mississippi Soybean Fields

Conservation management practices can improve soil health while minimizing deleterious effects of agriculture on the environment. However, adoption of these practices, particularly cover crops, is not widespread, as they often reduce crop yields compared to traditional management practices. The purpose of the current study was to determine if a two-species cover crop treatment of rye (Secale cereale L.) and crimson clover (Trifolium incarnatum L.) could increase soil health parameters and maximize soybean (Glycine max L.) yield greater than rye only in tilled and no-till Mississippi field soils. Enhanced microbial biomass and organic matter input from cover crops increased the activities of β-glucosidase, cellobiohydrolase, fluorescein diacetate hydrolysis, N-acetylglucosaminidase, and phosphatase in surface soils. Rye plus clover tended to elicit higher activities than rye only in no-till plots. Both cover crop treatments inhibited soybean yield in tilled plots by 11–25%. These results indicate that tillage exacerbates yield inhibition by cover crops in soybean and that double-species cover crop treatments were more consistent in increasing activities linked to nutrient cycling. Further study examining different combinations of cover crops in no-till systems is necessary to gain a better understanding of how they can be implemented to enhance soil health while maximizing crop yield.

Autonomous Mowing and Complete Floor Cover for Weed Control in Vineyards

Enhancing vineyards sustainability and reducing herbicides usage is a crucial theme, thus alternative weed management methods are starting to be studied. Cover crops have been shown to provide for several environmental services such as performing an efficient weed control and promoting biodiversity, thus improving the sustainability of the overall management system. However, the use of cover crops is usually confined to the interrow area in order to avoid competition with vines. Under-trellis weed management in vineyards is an important challenge, conventionally fulfilled by cultivation or repeated herbicides applications. Autonomous mowers are small autonomous machines that have shown a great efficiency when employed in agricultural contexts. Due to their reduced size, they can easily prevent the excessive vertical growth of weeds both in the interrows and under trellis without the use of chemical applications. The aim of this trial was to evaluate if the combination of cover crop species and autonomous mowers management could improve vineyard sustainability. Vineyard floor cover that was managed with an autonomous mower had a shorter canopy height and a lower weed dry biomass compared to the conventionally managed vineyard floor cover. Vineyard floor management providing cover crops and autonomous mowing had a significantly lower weed cover percentage compared to conventional floor management, especially under-trellis. The results of this trial suggest that the combination of cover crops and autonomous mowers may be a sustainable and reliable technique to include in vineyards floor management.

Soil Biological Response to Integration of Cover Crops and Nitrogen Rates in a Conservation Tillage Corn Production System

Core Ideas Use of N‐fertilizers decreased AMF populations and P, Ca, and Mg concentrations. Conservation tillage and cover crops increased C, N, and S cycling enzymes. Grass and brassica cover crops increased microbial populations compared to legumes. Agricultural production in the US Mid‐South has relied on frequent tillage and synthetic fertilizers decreasing soil health and system sustainability. Conservation tillage and cover crops can fill a vital role in reducing soil erosion while improving ecosystem functions. Seven cover crop blocks, including four legumes (berseem clover [Trifolium alexandrinum], crimson clover [Trifolium incarnatum L.], winter pea [Pisium sativum L.], and hairy vetch [Vicia villosa Roth], three grass & brassica (cereal rye [Secale cereale], forage radish [Raphanus sativus var. longipinnatus], and a cereal rye–forage radish mix), and one fallow control were established in northeast Louisiana to examine the influence of cover crop and urea fertilizer application rates (0, 235, 268, 302 kg N ha−1) on corn production and soil health under conservation tillage. Soil health indicators were measured each year following corn harvest and cover crop termination. The combination of cover crops and conservation tillage increased C and N enzyme activity over the 2 yr while arylsulfatase increased in the spring following cover crop termination only. Relative abundance of saprophytic fungi tended to be higher in legume plots compared to grass & brassica treatments. Overall, the application of N fertilizer at rates of 235 kg N ha−1 or higher decreased populations of AMF and concentrations of P, K, Ca, and Mg, but increased populations of Gram‐positive bacteria. The use of grass & brassica cover crops promoted K, S, Ca, and Mg availability, and supported greater abundance of total FAMEs and all FAME biomarkers except for saprophytic fungi.

Impact of Indian mustard growth and incorporation on annual weed population dynamics and communities

SummaryBiofumigation from Brassica cover crops may be used to control soilborne pests and weeds. A study was conducted to understand the influence of biofumigation on key processes of annual weed population dynamics. Five combinations of Indian mustard (M) and oat (O) cover crop treatments were assessed in a 3 year field study at two locations in Québec, Canada. Treatments included four spring/fall cover crop combinations (M/M, M/O, O/M, O/O) and a weedy check control with no cover crop. Prior to mowing and incorporation of cover crops, weed identification, count and biomass measurements were recorded to evaluate the total weed density, to calculate the relative neighbour effect (RNE) and weed diversity metrics and to perform principal co‐ordinates analyses. Indian mustard cover crops had no impact on weed establishment in 2014 due to low biofumigant potential compared to the oat cover crop. In 2015 and 2016, Indian mustard isothiocyanate (ITC) production increased and weed establishment within the Indian mustard cover crop decreased. Moreover, post‐cover crop incorporation decreased the next year spring weed emergence. Allelopathic interference of Indian mustard was significant when plant tissues produced more than 600 μg of allyl‐ITC g−1. It is now possible to rationalise the use of Brassica cover crops and biofumigation for weed control with an enhanced understanding of the impact of biofumigation on key processes of weed population dynamics.

Evaluating Mustard Seed Meal for Weed Suppression in Potato (Solanum tuberosum)

Mustard seed meal (MSM) derived from Sinapis alba controls weeds for several weeks following application to soil, but also has potential to injure the planted crop. Producers of certified organic potatoes typically utilize a combination of cover crops, soil hilling, harrowing, and cultivation for weed control. Once the potato canopy nears row closure, most late emerging weeds are suppressed by the dense potato canopy. MSM may have value for early season weed suppression in potato, but has not been previously tested. Our objectives were to determine the weed control efficacy and potato tolerance to MSM. We evaluated response of potatoes and weeds to MSM applied at 1.1, 2.2, and 4.5 MT ha-1 applied in a band on the potato hill just after a shallow harrowing and prior to potato emergence as part of an integrated weed management program in potatoes. MSM applied at 2.2 and 4.5 MT ha-1 reduced early season grass and broadleaf weed density 73 to 99% and 54 to 98%, respectively, in potato and reduced late season broadleaf weed biomass 71 to 94% in all three years tested. Early season grass weed density in potato was reduced by MSM at 2.2 and 4.5 MT ha-1. Late season grass weed biomass was reduced by the highest rate of 4.5 MT ha-1. MSM at 4.5 MT ha-1 caused minor injury to potato (3 to 15%) at 3 weeks after emergence, but did not reduce total tuber yields or percentage of US No.1 tubers. MSM could be a component of an integrated weed control program in potato.

Organic carbon and nitrogen contents and their fractions in soils with onion crops in different management systems

The use of plant species in rotation or succession of crops can increase C and N contents and their fractions in the soil. The objective of this study was to evaluate the effect of using soil cover crops in succession and rotation with onion crops in different soil management systems on the total organic carbon (TOC), total nitrogen (TN), and C and N fractions in soil aggregates, and bulk soil. The experiment was implemented in April 2007 with eight treatments: succession of onion and maize in a no-tillage system (NTS) (T1); rotation of soil cover crops (winter) and biennial onion in a NTS (T2); rotation of maize, winter grasses, and onion in a NTS (T3); succession of summer legume and annual onion in a NTS (T4); rotation of summer grass, winter grasses, and annual onion in a NTS (T5); succession of summer legume, winter grass, and annual onion in a NTS (T6); succession of maize and onion in a conventional tillage system (CTS) (T7); and succession of intercrops of soil cover crops (summer), and annual onion in a NTS (T8). Undisturbed soil samples were collected in the 0.0–5.0, 5.0–10.0, and 10.0–20.0cm soil layers in July 2014, and their aggregate (8.0 to 2.0mm) and bulk soil (<2mm) fractions were separated to evaluate their TOC, TN, particulate organic carbon and particulate organic nitrogen (OCP and ONP respectively), and mineral-associated organic carbon and mineral-associated organic nitrogen (OCM and ONM respectively). Soil turning due to the CTS in T7 (0.0–5.0cm) reduced TOC, OCP, OCM, TN, ONP, and ONM, in the soil aggregates and in the bulk soil, when compared with the NTS with the use of soil cover crops in succession or rotation with onion crops (T1–T6 and T8). T6 increased the TOC, TN, OCP, OCM, ONP, and ONM contents in the soil aggregates and bulk soil when compared with the successions with only grasses or only legumes. T1 increased the soil TOC and TN contents in aggregates compared with the same succession in CTS. T8 had higher OCP (0.0–20.0cm) and ONP (5.0–10.0cm) contents in aggregates than in the bulk soil. In general, aggregates had higher TOC and OCM contents, and bulk soil had higher TN, OCP, ONP and ONM contents. The main changes resulting from the management systems and soil cover crop combinations used were observed in the particulate fraction, especially in the soil aggregates.

Soil quality response to cover crops and amendments in a vineyard in Nova Scotia, Canada

The effects of cover crop mixtures combined with organic and industrial wastes on selected soil properties were assessed in a vineyard in Eastern Canada. The experimental treatments were randomly arranged in a nested design with three replicates. Four alleyway cover crop mixtures [control with no cover crop (CONT), oats+pea+hairy vetch (OPV), oats underseeded with red clover (ORCl), and timothy+alsike+red clover (TM)] were applied to main plots. Five fertility treatments [fertilizer without N (NDEF), full synthetic fertilizer (FERT), wood ash (WA), municipal solid food waste (MSFW), and mussel sediment (MS)] were assigned to sub-plots. Changes in selected soil quality (0–15cm) were assessed at the beginning of the growing season (May 9, 2011 and April 28, 2012), at bloom in early-July (July 06, 2011 and 2012), and at harvest in late-October (October 31, 2011 and October 20, 2012). At bloom, soil mineral N was 23.56kgha−1 for OPV and 20.68kgha−1 for ORCl, but only 16.38kgha−1 for CONT and 12.53kgha−1 for TM. At harvest, soil mineral N was 21.95kgha−1 for ORCl, but only 15.43kgha−1 for OPV and TM and 9.10kgha−1 for CONT. Soil mineral N was mainly in the form of NO3−–N until bloom, but at harvest majority of soil mineral N was consisted of NH4+–N. After one year of experiment, the three organic and industrial amendments maintained greater soil pH (7.34 for MSFW and 7.35 for WA) and Mehlich-3 extractable P (399kgPM3ha−1 for MSFW and 333kgPM3ha−1 for WA) compared with FERT (pH 7.17; 306kgPM3ha−1) and NDEF (pH 7.12; 288kgPM3ha−1) treatments. After two years of experiment, the combination of cover crop×amendment improved soil organic-C by 8.8% and 10.6% and -N by 8.1% and 9.8% compared with amendment alone and cover crop×FERT treatment, respectively. Potentially mineralizable N estimated by UV-absorbance of NaHCO3 extraction was greater under ORCl (0.79 abs) compared with the other cover crops (0.69 abs). The microbial biomass C was 205kgha−1 under MSFW and 212kgha−1 under WA, but only 168kgha−1 under NDEF, 125kgha−1 under FERT. The combination of cover crops and organic or industrial wastes provide comparable soil mineral N supply and available P with fertilized treatments while improving soil physical and biological properties and overall soil quality in this vineyard production system.

Improving Soybean Performance in the Northern Great Plains through the Use of Cover Crops

Cover crops are capable of providing multiple benefits for improving soil quality and enhancing annual crop growth. Maintaining continuous plant cover on agricultural fields with cover crop is of great interest to improve nutrient cycling, prevent soil degradation, and promote further adoption of no-till farming systems. A field study was conducted in eastern South Dakota, USA, in 2007, 2008, and 2009 to evaluate four cover crop combinations [(1) no cover; (2) buckwheat (BUCK) (Fagopyrum esculentum Moench) + slender wheatgrass (Agropyron caninum L.) (SLD WHT); (3) oilseed radish (Raphanus sativus L.) (RAD) + SLD WHT; and (4) purple top turnips (Brassica rapa L.) (TURN + SLD WHT)] sown after oat (Avena sativa L.) on soybean [Glycine max (L.) Merr.] performance. The impacts of no tillage (NT) and conventional tillage (CT) were evaluated at two different planting populations. Soybean plant biomass, seed harvest index, yield, total nitrogen (N), oil concentration, and test weight were measured. Cover crops preceding soybean did not negatively impact most measured plant parameters. Seed yield was increased by the RAD + SLD WHT and TURN + SLD WHT in 2008, whereas in 2007 and 2009 no yield increase or slight yield decrease was shown by the cover crops. Soil tillage practice and planting population had a strong influence on seed yield and seed quality in all three study years.

Do cover crop species and residue management play a leading role in pepper productivity?

There is a growing interest in improving sustainability in Mediterranean vegetable cropping systems by using winter cover crops. A 2-year field experiment was carried out with the aim of assessing the effect of cover crops and their residue managements on the following pepper (Capsicum annuum L.) crop productivity. Treatments consisted of factorial combinations of cover crops [hairy vetch (Vicia villosa Roth.), oat (Avena sativa L.) and no cover], residue management systems [tilled (as green manure, GM), or mowed and placed in strips in the crop row (as dead mulch, M)]. Cover crops were sown in early September and mechanically suppressed in May about one week before pepper transplanting. The pepper was transplanted in paired rows which were placed in the middle of the mulch strips in M treatments, the same geometry was maintained in the other treatments. The pepper crop was not fertilized and mechanically weeded twice only in the inter-row space between the paired rows in order to minimize agronomical inputs. At cover crop suppression, hairy vetch showed the highest aboveground biomass and total nitrogen content (712gm−2 of DM and 197kg of Nha−1, respectively), while oat exerted the strongest weed reduction. The marketable pepper yield was higher in hairy vetch than oat and no cover regardless of residue management (on average 25.4, 9.9 and 12.0tha−1, respectively) probably due to an abundant availability of soil nitrate throughout the pepper growing season. This was confirmed by high and constant values of SPAD readings of pepper plants grown in hairy vetch. Cover crop residues placed in strips suppressed weeds more effectively than incorporated residues. A better nitrogen nutrition and weed control led to an increase in pepper productivity cultivated in vetch mulch strips. Therefore combining legume cover crops and a strip mulching technique to manage cover crop residues could contribute to effectively increasing the crop productivity and consequently the yield of the following pepper crop. This management package could be considered an important option for organic and conventional growers seeking a way to reduce the agronomical inputs in a winter cover crop–pepper sequence.

Tillage System and Cover Crop Effects on Soil Quality: I. Chemical, Mechanical, and Biological Properties

Optimal use of management systems including tillage and winter cover crops is recommended to improve soil quality and sustain agricultural production. The effects on soil properties of three tillage systems (as main plot) including direct drilling (D), harrowing to a depth of 8 to 10 cm (H), and moldboard plowing (MP) with and without a cover crop were evaluated in a long-term experiment on a sandy loam soil in Denmark. Chemical, physical, and biological soil properties were measured in the spring of 2012. The field measurements included mean weight diameter (MWD) after the drop-shatter test, penetration resistance, and visual evaluation of soil structure (VESS). In the laboratory, aggregate strength, water-stable aggregates (WSA), and clay dispersibility were measured. The analyzed chemical and biological properties included soil organic C (SOC), total N, microbial biomass C, labile P and K, and pH. Reduced tillage (D and H) resulted in a stratification of the chemical properties within the 0- to 20-cm topsoil layer but a uniform distribution for MP. There was an accumulation of SOC, total N, and labile P and K and reduced pH in the 0- to 10-cm layer. Reduced tillage increased soil strength in terms of greater MWD, VESS, WSA, aggregate tensile strength, and rupture energy. Five years of using a cover crop alleviated plow pan compaction at the 20- to 40-cm depth by reducing penetration resistance. A significant interaction between tillage and cover crop treatments indicated the potential benefit of using a combination of cover crops and direct drilling to produce a better soil friability. The usefulness of the VESS method for soil structural evaluation was supported by the high positive correlation of MWD with VESS scores.

Produtividade do milho em condições de diferentes manejos do solo e de doses de nitrogênio

Pesquisas têm sido desenvolvidas buscando identificar a melhor dose de N para o milho nos mais diferenciados sistemas de manejo do solo. Contudo, não há ainda concordância quanto aos resultados, pois a dinâmica desse nutriente é influenciada pelo manejo do solo e pelas coberturas vegetais. O objetivo deste trabalho foi avaliar a produção de matéria seca e acúmulo de nutrientes em coberturas vegetais e produtividade do milho em sucessão, submetidos a diferentes manejos do solo e de doses de N. Os experimentos foram conduzidos no município de Selvíria, MS, durante os anos agrícolas 2009/2010 e 2010/2011, sob Latossolo Vermelho distrófico típico argiloso. Foram estabelecidos 36 tratamentos com quatro repetições, em blocos casualizados, resultantes da combinação de coberturas vegetais (milheto, Crotalaria juncea e milheto + Crotalaria juncea), manejo do solo (preparo com escarificador + grade "leve", grade "pesada" + grade "leve" e sistema plantio direto) e doses de N em cobertura (0, 60, 90 e 120 kg ha-1 - ureia como fonte). O híbrido de milho utilizado foi o DKB 350 YG® e o N, aplicado no estádio V5 (quinta folha expandida). Ocorreu incremento linear do índice de clorofila foliar, teor de N foliar, comprimento e diâmetro de espiga, massa de 1.000 grãos e produtividade, com o aumento nas doses de N em cobertura. A utilização de crotalária e de milheto + crotalária como antecessoras, associada à aplicação de 120 kg ha-1 de N em cobertura, proporcionou maior produtividade do milho após dois anos agrícolas.

Coberturas vegetais, manejo do solo, doses de nitrogênio e seus efeitos na nutrição mineral e nos atributos agronômicos do milho

Pesquisas são desenvolvidas buscando identificar a melhor dose de N para o milho nos mais diferenciados sistemas de manejo do solo. O objetivo deste trabalho foi avaliar a influência de coberturas vegetais, os sistemas de manejo do solo e as doses de N em cobertura sobre a produção de matéria seca, nutrição mineral, quebramento e altura de planta e inserção de espiga do milho. Os experimentos foram conduzidos no município de Selvíria, MS, durante os anos agrícolas 2009/2010 e 2010/2011, em Latossolo Vermelho distrófico típico argiloso (20º 20' S e 51º 24' W, com altitude de 340 m). Foram estabelecidos 36 tratamentos com quatro repetições, em blocos casualizados, resultantes da combinação entre coberturas vegetais (milheto, Crotalaria juncea e milheto + Crotalaria juncea), manejo do solo (preparo com escarificador + grade "leve", grade "pesada" + grade "leve" e sistema plantio direto) e doses de N em cobertura (0, 60, 90 e 120 kg ha-1 - utilizando-se ureia como fonte). O híbrido de milho utilizado foi o DKB 350 YG® e o N, aplicado no estádio V5 (quinta folha expandida). O cultivo de crotalária e de milheto + crotalária, como antecessoras, resultou em maior massa de matéria seca da parte aérea, teor de P foliar e quantidade de N, P e K acumulada. O sistema plantio direto proporcionou maior população inicial e final de plantas e matéria seca de parte aérea e menor altura de planta e de espiga. A aplicação de 120 kg ha-1 de N em cobertura proporcionou maior teor de P foliar, teores de N e de P na planta inteira, matéria seca de parte aérea, quantidade de N, P e K acumulada, altura de planta e de inserção de espiga do milho.

Adubação nitrogenada em feijoeiro em sucessão a cultivo solteiro e consorciado de milho e Urochloa ruziziensis

A expansão do sistema plantio direto, no Brasil, está diversificando, cada vez mais, as formas como os métodos de produção são implantados e manejados. O presente estudo objetivou avaliar a influência de culturas antecessoras como o milho e Urochloa ruziziensis, bem como o consórcio entre estas, na presença e ausência de inoculação de sementes com Azospirillum brasilense, e o fornecimento de nitrogênio em cobertura sobre o desenvolvimento do feijoeiro e de seus componentes de produção e produtividade de grãos. O trabalho foi desenvolvido em Selvíria (MS), na safra 2011/2012. O delineamento experimental foi o de blocos ao acaso, com quatro repetições, em esquema fatorial 8x4, cujos tratamentos foram constituídos pela combinação de restos culturais (associações de milho, U. ruziziensis e A. brasilense) e doses de nitrogênio em cobertura no feijoeiro (0 kg ha-1, 30 kg ha-1, 60 kg ha-1 e 90 kg ha-1). As culturas antecessoras apresentaram efeitos na produtividade do feijoeiro, sendo o consórcio de milho e Urochloa, ambos inoculados, a melhor opção. A população inicial do feijoeiro não foi afetada pelas culturas antecessoras. A aplicação de nitrogênio em cobertura não interferiu na produtividade do feijoeiro, em cultivo irrigado de inverno, sob plantio direto.

Study of Single and Combination Application of Cover Crops and Their Removal Time on Weed Suppression in Sugar Beet Fields

In order to study the effect of different combinations of cover crops and time of their removal on weeds population in sugar beet fields, an experiment was conducted at the Iranian Research Institute of Plant Protection, . The study was based on two factorial experiments with randomized complete blocks design with four replications. Treatments in first experiment were type of cover crop including: 1) X Triticosecale wittmack, 2) Hordeum vulgare, 3) Trifolium alexandrium), 4) Raphanus sativus and removal times including: 1) at four-leaf sugar beet stage, 2) at eight-leaf stage of sugar beet. In the second experiment, different combinations of cover crops were evaluated. Treatments were cover crop combination including: 1) Hordeum vulgare & Raphanus sativus, 2) X Triticosecale wittmack & Raphanus sativus, 3)Hordeum vulgare & Trifolium alexandrium, 4) X Triticosecale wittmack & Trifolium alexandrium and removal time of cover crops (as the same of the first experiment). The results showed significant effects of different cover crops and their removal times on weeds dry weight and population. Between treatments, combination of X Triticosecale wittmack & Trifolium alexandrium had the lowest weed dry weight and population when removed at four-leaf stage of sugar beet.