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In the South of Córdoba province, the simplification of agricultural production systems has increased the risk of wind erosion, due to changes in the dynamics of vegetation cover and land use. Therefore, our objectives were to evaluate the soil erodible fraction by wind in response to different management practices and environments in southern Córdoba province and to relate it to soil properties. For them, in three macro-environments (West, Central and East southern Córdoba) under four soil uses: Forest (P), Mixed (M), Agriculture without peanut crop (A0) and Agriculture with peanut crop (A1), undisturbed samples were taken for the determination of the wind erodible fraction (FE) using a rotary sieve. Additional samples were taken for the determination of organic matter (OM) and texture. There was interaction between soil use and the macro-environment for FE. In West and East southern Cordoba, FE was similar among soil uses with values above the threshold in the former and below the threshold in the latter. In the Central macro-region, FE of A1 was higher, with values above 40%. A linear negative relation was observed between FE and OM, whereas a linear positive relation was established between FE and sand content. In soils with above 70% sand, the use of service crops is necessary to control erosion, while this threshold is reduced to 60% for those sequences with peanut crop. [ABSTRACT FROM AUTHOR]

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research study assessed the use of Pueraria phaseoloides crops as cover in oil palm (Elaeis guineensis) plantations to improve the ecological function of soils under tropical conditions. The plots examined (90 palms·ha-1) were established 5, 7, 11, and 30 years ago. The results showed a high and stable specific coverage index that ranged between 52 and 87%. This enhanced soil moisture by reducing the incidence of solar radiation. It also increased competitive capacity with the complex of weeds present and improved soil nutrient averages (1.60 mg/L N and 0.42 mg/L P). Fruit bunch average yields also improved in the short term, ranging from 10.6 to 22.4 t·ha-1, with more frequent harvest events when compared to the control. It is concluded that Pueraria phaseoloides is a sustainable alternative to improve the establishment of plantations under tropical conditions. [ABSTRACT FROM AUTHOR]

Water and nitrogen (N) are the main factors that generate the greatest limitations in food production. The use of cover crops (CC) due to their multiple benefits, can modify soil water and nitrate dynamic. It is therefore important to know the interaction between cash crops and CC. The objectives of this work were to evaluate the interaction between rye as CC and cash crops over the dynamics of water and N; and the synergy between crops. For these objectives, samples were taken to measure soybean and corn yield and rye dry matter production (DM) and soil samples to measure evolution of the water content and available N as nitrate due to the presence of the different crops in a long-term experiment located in General Villegas (Buenos Aries) during the 2010/11, 2011/12 and 2012/13 period. As a result, the DM production of the CC was increased (between 30 and 150%) with soybeans as a predecessor and when it was fertilized. No differences in general were observed in the availability of water due to the use of CC. Regarding the concentration of N in soil, it was observed a decrease of it concentration probably due to the consumption of CC in the soybean treatments. Finally, the yields of cash crops in general were not affected, except for a single year where corn production was statistically higher in the treatment without CC (between 1000 and 2000 kg ha-1). Therefore, it is necessary to adjust CC management according to climatic situations and the cash crop. [ABSTRACT FROM AUTHOR]

In order to evaluate the effect of when we kill the cover crop on the yield of a late corn, under the hypothesis that as the desiccate date is delayed, it will increase the carbon sequestration the amount of nitrogen (N) immobilized in the biomass (lower C/N ratio) and weed suppression and it will reduce the water soil storage for the next crop. Trials established in completely randomized blocks with four repetitions of the following treatments: 1st drying date (july), 2nd drying date (august) and 3rd drying date (september), in turn, each plot was divided in half to establish treatments with and without nitrogen fertilization in the corn crop. Total water (AT), aerial production and carbon and nitrogen; root biomass production, consumptive use (UC), water use efficiency (WUE) and nitrogen availability and yield were determined. The results obtained in the treatment of the 1st drying date were: production of air biomass of the CC of 3015 Kg MS.ha-1, production of root biomass of the CC of 1765 Kg.ha-1, UC of 237 mm, USA of 12.2 Kg.ha-1.mm-1 and corn yield of 6566 Kg.ha-1. For the treatment 2 nd drying date were: production of aerial biomass of the CC of 5060 Kg MS.ha-1, production of root biomass of the CC of 6352 Kg.ha-1, UC of 260 mm, USA of 20 Kg.ha-1.mm-1 and corn yield of 6450 Kg.ha-1. Finally, for the treatment of the 3rd date of drying were: production of aerial biomass of the CC of 8252 Kg MS.ha-1, production of root biomass of the CC of 4000 Kg.ha-1, UC of 347 mm, USA of 24.2 Kg.ha-1.mm-1 and corn yield of 5931 Kg.ha-1. The drying time of the CC have an influence on the yield in the Pampean Semi-Arid Region, given a moisture regime of the Utic type, typical of that region. [ABSTRACT FROM AUTHOR]

The sustainability of agricultural environments in the Humid Argentine Pampean Region is affected by the monoculture of soybean (Glycine max (L.) Merr.). The low efficiency in the use of environmental resources during fallows and its negative effect on the sustainability and productivity of production systems makes it necessary to adopt practices such as the inclusion of a winter cover crop (CC) between the income summer crops. In a soybean-soybean sequence, the effect of a cover crop of oats (Avena sativa L.) and vicia (Vicia sativa L.) on the contribution of carbon (C) through the dry matter (DM) produced, the available soil water (AUD) and the yield of the subsequent soybean crop were evaluated, considering environments differentiated by the slope. The treatments with CC (CCC) presented more AUD in soybean planting and flowering, higher soybean yields and greater contributions of C to the system. [ABSTRACT FROM AUTHOR]

Integrating cover crops (CC) in the crop sequence could lead to an enhancement of the notillage (NT) performance improving soil physical quality (SPQ). The objectives of this work were: i- to determine the SPQ on different moments of the crop cycle during the first year after incorporation of cover cropping (barley and vetch) (CC), as compared with bare fallow (BF); and ii- to measure the impact of cover crops on the top soil water content during the first year of its introduction. SPQ indicators were determined from the soil water retention curve (SWRC) and in-situ infiltration data in different dates during the first year after inclusion of CC. The experiment was carried out in a fine, illitic, thermic abruptic Argiudoll. For both treatments, maize was sown as summer crop. CC management showed higher values of plant available water content (PAWC) and Dexter index (S), and lower values of bulk density (BD) as compared with BF. Higher values of field capacity (FC) under CC were observed during the maize growing season. On the other hand, no differences between treatments were observed for Pmac. These results show that the inclusion of CC under NT management improves the soil capacity to retain water and counteract compaction processes under NT. At the end of the crop cycle, higher values of water-conducting macroporosity (εma) and macropore connectivity (Cwma) were observed under CC. Higher values of soil water content during the maize growing period were observed under CC, showing that the inclusion of CC has no negative effects on the top soil water content. Our results show that the inclusion of CC is an opportunity for intensify crop sequences in the Argentinean Pampas Region, oriented to enhance the performance of NT. [ABSTRACT FROM AUTHOR]

Copyright of Agronomía & Ambiente is the property of Universidad de Buenos Aires. Facultad de Agronomia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increased in frequency of soybean monoculture can lead to decreases in soil organic matter and affect soil physical properties. However, management practices such us fertilization, crop rotation with high biomass production and increases intensification sequence index (ISI) could partially offset agriculture negative effects. The aim of this work was to evaluate the effect of inclusion of different crops sequence management with soybean predominance on soil physical properties. The experiments were carried out at two sites of Pampas Region (Arequito and Balcarce): In both sites, different alternatives management effects on bulk density (Dap) and aggregate stability (EA) previous to soybean sown were evaluated. Additionally, mechanical resistance to penetration (RMP) and infiltration rate (TI) were evaluated only in Balcarce. The determinations were performed after 4 years of implementation of following treatments: soybean without fertilization (Sj); soybean with phosphorus (P) and sulfur (S) (SjF); cover crop (CC) / soybean with P and S (CC/SjF); CC with nitrogen (N) / soybean with P and S (CCF/SjF); high ISI rotation fertilized with N, P and S: wheat/soybean 2° - CC / soybean (Rotation). In both sites, Dap (0-5 and 5-10 cm soil depth) and AE values (0-10 cm soil depth) was not significantly different between crops sequence management practices. On the other hand, RMP (0 to 20 cm soil depth) and TI were not significantly different between treatments at Balcarce site. The results our experiment indicate that after 4 years of sequences with soybean predominance, P and S fertilization, CC inclusion, and rotation with high ISI, did not significantly affected soil physical quality indexs. [ABSTRACT FROM AUTHOR]

In Subachoque, Cundinamarca (Colombia) changes of air temperature (T°) and precipitation (P), are affecting Gold potato crop (Solanum phureja) productivity. The aim of this research was to create an alert for decision making in Gold potato crop. The methodology was in two ways: participative focus and statistical climatic analysis. Analysis showed a gradual increase in temperature in the town (ΔT° 0.05 C° between 1966 to 2017) and increase of dry years since the 90's (1951 to 2017). Annual analysis demonstrated that monthly P average is not enough to cover potato crop monthly water consumption, for this reason, farmers need to implement irrigation systems from December to February and July to August. It is recommended to plant from March or April and August or September since these periods have optimal state for P and T° variables for gold potato crop. [ABSTRACT FROM AUTHOR]

El crecimiento de cereales invernales en regiones semiáridas y subhúmedas es limitado por factores de estrés abiótico que podrían ser mitigados por la incorporación de microrganismos promotores del crecimiento. El objetivo fue cuantificar la evolución en la producción de biomasa aérea de cebada (Hordeum vulgare L.) como cultivo de cobertura inoculado con Azospirillum brasilense según dos niveles de fertilización. En dos sitios de la región semiárida región semiárida y subhúmeda pampeana, con condiciones hídricas iniciales contrastantes, se instalaron cuatro tratamientos combinando el tratamiento de semillas con Azospirillum brasilense y la fertilización en la siembra con fósforo y con nitrógeno. Durante el desarrollo de los cultivos no se observaron limitaciones aparentes en la normal provisión de agua. Los tratamientos de fertilización y de inoculación mostraron efectos independientes sobre la producción de biomasa aérea con aportes medios del 23% al inocular y del 44% al fertilizar. La mayor tasa de crecimiento al inocular ocurrió entre macollaje y encañazón adelantando el momento de máxima producción del cultivo. La inoculación de semillas de cebada con Azospirillum brasilense es una práctica recomendable para mejorar la contribución en la producción de cultivos de cobertura invernal y su integración en sistemas agrícolas con especies estivales. In semiarid and subhumid environments, plant growth promoting microorganisms mitigate abiotic stresses that frequently limit the grain production of winter cereals. Our objective was to quantify the field evolution of the shoot dry matter production of barley (Hordeum vulgare L.) cover crops inoculated with Azospirillum brasilense combined with two levels of fertilization. Four treatments combining a seed treatment with Azospirillum brasilense and nitrogen and phosphorus fertilization at sowing were placed in two sites from the semiarid and subhumid pampas region under contrasting initial water conditions. During the growing season, the water availability (rainfalls and water table contribution) was adequate for achieving normal growth of the crops. The fertilization and the inoculation treatments showed independent effects on the shoot biomass production with 23% mean response to inoculation and 44% mean response to fertilization. In the inoculated treatments, the greater shoot growth rate was observed between tillering and stem elongation anticipating the moment for maximum dry matter production compared with the treatments without inoculation. The inoculation of barley seeds with Azospirillum brasilense is a recommended management practice in dryland agricultural systems in the semiarid and subhumid pampas integrated with the production of annual summer crops. [ABSTRACT FROM AUTHOR]

Cover crops (CC) are used traditionally to control erosion problems, improve water collection, distribution and storage, reduce compaction, and improve soil carbon and nitrogen balances. This work aimed to provide zonal results regarding the contributions of CC on resource use efficiency and sunflower productivity. During 2017 and 2018, six CCs as sunflower predecessors in Coronel Suárez (Southwest of Buenos Aires) were tested. Soil water and dry matter, nitrogen and vegetable yield were evaluated. The difference in edaphic water content upon drying of the CC with respect to the conventional fallow (BC) varied between -8 and 15 mm. The water use efficiency (EUA) ranged from 5.59 kg MS mm-1 in vetch (V1) and 16.16 kg MS mm-1 in oats (A). The highest yields were obtained with V1 (2379 kg ha-1) and the lowest with A (1561 kg ha-1). [ABSTRACT FROM AUTHOR]

Assessing agricultural systems effects on the environment is essential to minimize any negative impact. This study evaluates water, sediments and herbicides losses by runoff on different crop sequences due to a precipitation event following spraying of herbicides. Measurements were conducted in natural-rainfall runoff plots at INTA Paraná. Crop sequences were: soybean monoculture (S), soybean monoculture with wheat as cover crop (CC-S), and both wheat / soybean as cash crops (T / S). All sequences were sprayed with glyphosate and clethodim before soybean's sowing. Compared to the amount applied, the proportion of glyphosate and clethodim in runoff ranged between 5.3-13.5% and 2.6-5.9%, respectively. Losses of soil and AMPA (concentration) were greatest for S. The results highlight the importance of checking meteorological forecast conditions before spraying of herbicides to reduce nonpoint pollution of water bodies. [ABSTRACT FROM AUTHOR]

In fragile irrigated agro-ecosystems like those in Mendoza, with low fertility soils, scarce rainfall and high summer evapotranspiration, climate change will have a significant impact. Agricultural practices with tillage and intensive use of agrochemicals generate serious ecological imbalances. This problem requires the redesign of these systems and a reconsideration of its practices. The Agricultural Experimental Station of INTA Mendoza worked on the transition to vineyard management systems with an agroecological approach. In a demonstrative and experimental vineyard plot, biological corridors and diverse cover crops were established, studying different methodologies of elaboration of compost, compost tea, bio-slurry and their periodic application to the crop. We evaluated alternative technologies for weed control and phytosanitary programs with lower environmental impact. The proposed practices allowed increasing biodiversity of species in the vineyard, improving soil fertility and achieving productive levels close to those of conventional management. In the course of nine agricultural seasons, the sanitary conditions of the vineyard were satisfactorily maintained. Finally, operating costs were close to those of conventional management. [ABSTRACT FROM AUTHOR]

Green bridge crops (CPV) effect on soil and succeeding cash crops depends on the type of CPV and on how their residues decompose. We hypothesized that 1) decomposition rate of grass CPV is lower than that of legume CPV; 2) decomposition dynamics of CPV legume will lead to a higher and faster availability of nitrogen (N); and 3) residue decomposition will lead to a higher but delayed increase of labile soil organic matter fractions with grass CPV and when located on soil surface. We carried out an experiment on a Typic Argiudoll with CPV with oats (Avena sativa L.), vetch (Vicia villosa Roth.) and a control without CPV (TE). Equal amounts of chopped residues of both CPV were placed on surface and mixed with soil (buried). We took soil samples at 0-20 cm in 7 moments along 133 days to determine remnant residue (CR), carbon (C), total (COT), and particulate organic C (COP), ammonium N freed in anaerobiosis (NAN), and nitrate N (N-NO3 -). Remnant C of both CPV decreased over time, but at a higher rate when buried with differences between vetch and oats. On surface, vetch residues decomposed faster than oats residues, at the end of the experiment, 60 and 79% of the residues, respectively, had decomposed. Neither COT, COP, nor NAN changed along the experiment. After oats, COT and COP (75.1 y 18.6 Mg ha-1, respectively) were higher than after vetch and TE (70.4 y 16.8 Mg ha-1, respectively). Besides, these were lower when residues were buried (69.7 y 15.,9 Mg ha-1, respectively) than when residues were left on surface (73.3 y 18.9 Mg ha-1, respectively). The position of residues did not affect NAN, but it was higher after oats and vetch (63.1 mg kg-1) than after TE (50.2 mg kg-1). Up to 49 days from the start of the experiment there was an increase of N-NO3 - (45 up to 108 kg ha-1). N-NO3 - was higher when CPV was vetch and there was no difference between oats and TE. We did no collect enough evidence to reject the first and the second hypothesis, but evidences were enough to reject the third one. [ABSTRACT FROM AUTHOR]

Legume cover crops are planted to control weed, to prevent soil erosion, and to increase nitrogen in soil. The objective of this study was to evaluate the response to phosphorus fertilization of the legumes Mucuna pruriens cv. cinza, Mucuna pruriens cv. preta, Crotalaria spectabilis, Vigna radiata, and Pueraria phaseoloides, during two seasons of the year. The experiment was carried out in a greenhouse at the Agricultural Experiment Station Fabio Baudrit Moreno (EEAFBM, in Spanish), of the University of Costa Rica, Alajuela, Costa Rica, from November 2012 to January 2013, and it was replicated from April to May 2013. Doses of 0, 30, 60, and 90 kg P2O5/ha were applied on steam sterilized soil, an then it was used to fill 2 kg capacity pots. The variables assessed were plant height, number of true leaves, and dry weight 18-26 days after planting, depending on legume species. Crotalaria spectabilis, V. radiata, and P. phaseoloides achieved the highest growth when fertilized at the rate of 60 kg P2O5/ha, whereas both M. pruriens cultivars did not increase growth as a response to phosphoric fertilization. Due to the positive effect of phosphorus fertilization on growth of small seeded legumes, it is important to validate the use of this fertilizer to achieve rapid soil cover, which could decrease weed competition. [ABSTRACT FROM AUTHOR]

In this paper, we study the dynamics of transition in the interaction between vine (Vitis vinifera L.) and cover crop. From data obtained in a field essay, we propose a statistical model to investigate such biological interaction and we could determine that the vine-cover crop system changed from a biological interaction of commensalism type to another of amensalism type, being the vine not affected. Based on this information, we formulate a biomathematical model to describe this interaction, we estimate its parameters, and analyze the stability of the equilibrium points. It is evident, in this study, that the cover crop does not affect vine growth during the period considered in the essay. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the knowledge on cover crops and native vegetation mulches and the willingness to implement them by papaya, oil palm, and banana producers in Costa Rica. An evaluation instrument with twenty eight questions to be answered as true or false was developed, and it was used to yield a knowledge indicator. Seven additional questions with responses on a scale from 0 to 5 were included to explore producers' willingness to implement cover crops or native vegetation mulches on their farms. The evaluation was completed in 2014, and was filled out by 36 papaya producers, 30 oil palm producers, and 57 banana producers. Item analyses to determine reliability produced Cronbach's alpha values above 90%. For this study a factors analysis was performed in order to determine the measurement of one single variable, knowledge on cover crops and native vegetation mulches. Global knowledge scores varied significantly between producer groups. Banana producers assessments yielded the highest mean with the lowest variability, whereas papaya producers had the lower mean and the highest variability. Likewise, answers to each of the questions differed importantly between producer groups. It was also determined that producers of these crops are willing to implement and get training on cover crops and native vegetation mulches. [ABSTRACT FROM AUTHOR]

This work present data on microhymenopteran parasitoids found on natural areas and on vineyards subjected to different management practices. A total of 49 species and 230 individuals belonging to nine families, were found. The richest families were Encyrtidae and Braconidae. One of the three studied vineyards, whith perennial cover crop, showed a significant higher richness and abundance of microhymenopterans than the other sites. Faunistic similitude was low between vineyards and natural area. Grass cover was positively related with richness and abundance of microhymenopterans. [ABSTRACT FROM AUTHOR]

Biological soil attributes have shown to be good indicators of soil changes as a result of the management function. The aim of this study was to evaluate the effect of using cover crops, as well as planting and tillage systems on the biological attributes of a yellowish red latosol soil. Soil samples were taken at 0 to 0.10 m depth, seven days before the bean harvest. Microbial biomass carbon and nitrogen, basal soil respiration, metabolic ratio and total enzyme activity were evaluated in this study. The best agroecological management was achieved under the association of the ground cover with millet and in direct seeding because they showed higher soil microbial biomass carbon and nitrogen content and lower metabolic quotient, being pork bean the best plant coverage. All biological soil attributes were sensitive to the tillage system, which showed the best results of the total enzyme activity and of the soil metabolic quotient which resulted to be the most efficient. [ABSTRACT FROM AUTHOR]

During the last decade, the Pampean Semarid Region showed an increase in cropping area by including soils of low aptitude which, in consequence, became degraded. Cover crops are a tool that can minimize such edaphic degradation and offset the carbon balance. This work's objective was to evaluate the effect of three drying dates (DD) of rye, as cover crop (CC), on water use efficiency (WUE) and biomass production of the CC, soil content of available water and nitrate, and the presence of weeds in and grain yield of a maize successor crop. The field trial was conducted at the Experimental Station INTA Anguil, La Pampa, and the DD assayed for the CC were july, august and september. Results showed that CC biomass production and WUE were higher for drying in August and September as compared to that done in july. Contents of available water and nitrate in the soil profile, as well as maize grain yield, were significantly reduced with the delay of CC drying. There was no difference in the amount of weeds present in maize crop among v6 and v8 phenological stages, and neither in maize grain yield, whether or not herbicides were applied. [ABSTRACT FROM AUTHOR]

Copyright of Agriscientia is the property of Revista AgriScientia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cover crops (CC) have an effect on nitrogen (N) accumulation and on successive crop yields. The aim of this study was to evaluate yields, yield components and N accumulation of maize using as previous crops different CC and evaluating the response to N fertilization. Five experiments were conductedd on a Typic Argiudioll (USDA Soil Taxonomy) of Coronel Suárez. The species used as CC were: Oats (Avena sativa), Hairy vetch (Vicia sativa) and control (chemical fallow). The experimental design consisted of split-plots in three randomized complete blocks, with main plots corresponding to the cover crops treatment and subplots to the fertilizer treatment (N applied at the V4-V6 corn stage). The treatments in the main plots were the CC. The effects of CC varied according to the corn yield component.. Hairy vetch and N fertilization at different rates increased the N absorption efficiency. A greater N absorption was not always related to increases in corn yields, probably due to the climatic variability among years. There was a tendency for greater corn yields with hairy vetch as a preceding cover crop. N application reduced hairy vetch N recovery during the second year and increased N recovery during the first and third year. Fertilizer application effects varied among previous crops with a low response to N when the previous crop was hairy vetch, a variable response when in fallow and a significant response when the previous crop was oats. [ABSTRACT FROM AUTHOR]

Copyright of Agriscientia is the property of Revista AgriScientia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Allelopathic effect of the cover crops Tradescantia zebrina Shunltz (cucaracha) and Commelina diffusa Burm. F. (canutillo) were evaluated on Coffea arabica Lin. seeds Caturra Rojo variety. Germination tests were carried out “in vitro" and it was evaluated the root longitude, percentage of total germination and period of germination, as well as the height of the plant and the emergency percentage for the incorporation tests to the soil. It was also carried out, to both over crops, the preliminary chemical qualitative characterization. The results showed that the extracts of T. zebrina and of C. diffusa stimulated the “in vitro" germination and growth of C. arabica at different concentration levels. The incorporation to the soil of the extracts of C. diffusa stimulated the development of the plants of C. arabica, in a significant way, that supposes a considerable advantage in that concerns to the employment of these cover crops, when not implying noxious effects beside all the benefits implied when using cover crops. These last ones go from the protection and improvement of the properties of the soil, to the control of the spontaneous flora in the coffee agroecosystems. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of BIOAGRO is the property of Revista BIOAGRO and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The goal of this research was to develop a protocol for the in vitro culture of Geophila macropoda. The work was conducted in Guácimo, Limón, Costa Rica between June 2006 and February 2007. For the in vitro establishment phase, the explants used were micro-cuttings and zygotic embryos. Bacterial contamination prevented the establishment of high percentages of plant material, whereas the use of embryos resulted in a response as high as 89%. For shoot proliferation, five concentrations of benzylaminopurine (BAP) were tested. The best results were obtained with 2 mg/l BAP with 13.4 new seedlings from an original vitroplant. Rooting was accomplished in a half Murashige & Skoog medium, without adding any plant growth regulator. During the acclimatization period the survival rate was 100%. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the potential of three legumes as cover crops to improve maize production systems. Four treatments were evaluated: 1) control, maize in monoculture; 2) maize - short-cycle, white seed lima bean (Phaseolus lunatus); 3) maize - long cycle, white seed lima bean Phaseolus lunatus), and 4) maize - velvet bean (Mucuna sp.), in a randomized complete blocks design with four replications during four growing cycles (1999-2002), in Yucatán, México. We measured: crop biomass, pH, total N, potential anaerobic mineralization of N, CO2 evolution, potassium (K), phosphorus (P), and soil organic matter, and biomass and frequency of weeds. Legume stubble residues accumulated on maize crops were: 3436, 3425 and 4018 kg DM/ha for the first, second and third year, respectively. Nitrogen contributed by stubble material was 25.8, 31.9, 52.8, and 43.4 kg/ha in treatments 1, 2, 3, and 4, respectively. Maize grain yield was 841, 843, and 460 kg DM/ha in the first, second and third year, respectively, without significant differences between treatments. During the third year, velvet bean caused a reduction in weed biomass from 126 to 58 g DM/m². Cover crops had little influence on soil variables and maize grain yield. [ABSTRACT FROM AUTHOR]

In order to evaluate the establishment of five cover crops and their potential to increase soil fertility through nutrient uptake, an experiment was installed at the Research Station of Choclino, San Martin, Peru. Five cover crops were planted: Arachis pintoi Krapov. & W.C. Greg, Calopogonium mucunoides (L.), Callisia repens (Jacq.) L., Canavalia ensiformis (L.) and Centrosema macrocarpum Benth. The percentage of cover of Canavalia, was significantly higher than the others, reaching total cover at 90 days after planting. The highest above and below ground dry biomass was for Centrosema (9.61 t ha-1 y 2.76 t ha-1, respectively). The rates of Nitrogen (311 kg ha-1), Phosphorous (24.97 kg ha-1) and Potassium (155.61 kg ha-1) extracted by Centrosema were significatively higher than the other cover crops. Therefore, the most appropriate cover crop under the study conditions was Canavalia allowing it to be used as a management tool to reduce spontaneous vegetation growth and to protect the soil from erosion by covering it in less time. To improve soil fertility through nutrient cycling the use of Centrosema is recommended due to its highest nutrient extraction capacity and dry biomass production. [ABSTRACT FROM AUTHOR]

With the objective of evaluating and selecting cover crops to improve soil management in vineyards (Vitis vinifera L.) cv. Cabernet Sauvignon, five cover pastures were evaluated: a) control without vegetation; b) control with spontaneous vegetation; c) legume mixture of early maturing cultivars of subterranean clover (Trifolium subterraneum L.) and burr medic (Medicago polymorpha L.); d) legumes mixture of late maturing cultivars of subterranean clover and balansa clover (T. michelianum Savi); and e) legumes mixture of late maturing cultivars and annual ryegrass (Lolium rigidum Gaud.). The study was conducted at Cauquenes Experimental Center, Agriculture Research Institute (INIA), over two seasons, 2005-2006 and 2006-2007. The experimental design was randomized blocks with four replicates. The three pasture mixtures had a good establishment and achieved high populations. Biomass production was significantly higher (P ≤ 0.05) in the mixtures with late maturing cultivars of subterranean clover and balansa clover, compared to the mixture of early maturing cultivars of subterranean clover and burr medic (2.3 to 4 t DM ha-1 yr-1 and 5.3 to 6.2 t DM ha-1 yr-1 in the first and second year, respectively). The contents of N, P and K in the biomass of the cover crops were higher (P ≤ 0.05) than those covers with spontaneous species, which increased the content of available N in the soil. Higher contents of K and P were detected in the soil. The cover crops had an important detrimental effect on the population of the spontaneous species that grow in the inter-rows of the vineyard. [ABSTRACT FROM AUTHOR]

A study of the evaluation and selection of cover crops to improve soil management in an organic orchard of raspberry (Rubus idaeus L.) was carried out. The evaluated cover crops were: a mixture of subterranean clover (Trifolium subterraneum L.) and balansa clover (T. michelianum Savi), birdsfoot trefoil (Lotus corniculatus L.), white clover (T. repens L.), fescue (Festuca arundinacea Schreb.), a mixture of white clover and fescue, and a control without vegetation. The trial was conducted in Chillán, Chile (36°37' S, 72°00' W), during two seasons. The experimental design was randomized blocks with four replicates. Planting distance between raspberry rows was 3 m, and each experimental plot was 60 m2. Covers that included white clover as a single species and white clover in mixture with tall fescue had the highest plant density (828 and 1788 plant m-2, in the second year, respectively), biomass (9.3 and 10.4 t DM ha-1 yr-1, in the second year, respectively) and specific contribution of the sown species (more than 90% contribution of sown species). Mixture of annual species did not have a good performance, particularly during the second season. A clear effect of the covers on soil content of nitrogen (N) and potassium (K) was found; however, soil organic matter content and pH were not affected. Weed growth was best controlled by the cover crops that included fescue and/or white clover. [ABSTRACT FROM AUTHOR]

Erosion is a serious environmental problem that affects the whole world. In Cuba this phenomenon affects more than 40 % of the agricultural land. At this moment, the watershed of the river Cuyaguateje, one of the eight prioritized watersheds of the country, is facing serious erosion problems. Nowadays, there is a trend to determine the erosion of a region by using of simulation models. One of these models is RUSLE, an empiric model that makes use of different parameters, one of this the factor vegetation that analyzes the influence of the vegetation cover in the protection of the soil against the erosion. For the analysis of this factor, the model needs data of the crop development with time, however the crop data reported in the literature have been determined in conditions different to the ones existing in Cuba. In this work the factor vegetation is presented for the main cultivations present in the basin of the Cuyaguateje (tobacco, beans, maize, cassava and sweet potato), as well as the methodology followed for its determination. It was obtained the models that describe the behavior of these cultivations in function of the days after the planting date for the existing conditions in the watershed. The data obtained was later processed by the model RUSLE Crop Factor Calculator, obtaining the values of the factor C of RUSLE. The results indicate according the crop alternation used by the local farmers in the area under study, a reduction in the soil loss of more than 60 %. It is evidenced that in humid period corn cultivation exerts higher protection than sweet potato. This was not observed in dry period. Sweet potato in the studied period (dry period) has a development something lower to that of the humid period. [ABSTRACT FROM AUTHOR]

With the objective of determining the influence of the use of a covering vegetation (Lablab purpureus L. Sweet y Neonotonia wightii AM. Lackey) in the control of arvenses in a guava plantation (Psidium guajava L.) var. Enana, in a tropical climate, a study was done in fruit of 6 months of age, planted with a density of 6 m x 2 m, planted in a red ferralitic soil, with pH of 5.7 and value of both, P2O5 and K2O of 0.76 and 21.53 mg 100g-1, respectively. We used a randomized block design with four treatments (natural cover, bare soil, and cover of both leguminous) and four replicas. Each lot had 80 m² of area and it was shaped for adjacent stripes of trees evaluated. The legumes were seeded, on line, with a density of 6 kg ha, for minimum tillage. Results indicated a significant reduction (P <0,001) on amount of weeds in legume treatments and those where we apply herbicide, in relation to natural coverage. Legumes especially reduced both, the number of plants and number of species of class dicotyledonous. The weed biomass was significant (P<0,05) highest in natural cover than in legume covers; nevertheless, both, legumes biomass and total biomass were higher in L. Purpureus treatment. We recommend evaluate the effects of different treatments on soil properties and trees phenology of guava crop. [ABSTRACT FROM AUTHOR]

The effect of mulch and cover crops on the growth and yield of tobacco (Nicotiana tabacum L.) variety "Havana 2000" cultivated in a fluvisol soil was studied in the Cooperative of Agricultural Production (CPA) Camilo Cienfuegos in Buey Arriba municipality, Granma province. The species incorporated as mulch and cover crops were: corn (Zea mays L.), cowpea (Vigna unguiculata (L.) Walp), canavalia (Canavalia ensiformis (L.)), ajonjolí (Sesamum indicum L.) and sorghum (Sorghum vulgare Pers.); growth and yield indicators in plots incorporated with these plants were compared with those from a control plots without mulch or cover crops. No mineral fertilizers were used in any of the experimental plots. Incorporation of S. indicum and Z. mays plant residue caused significant increases in the length and width of the largest leaf of tobacco. The greatest production of leaf dry mass and stem dry mass was produced in plots with S. indicum and C. ensiformis soil incorporation before the tobacco crop, with respective yields of 2,021.7 kg/ha and 2,019.2 kg/ha. [ABSTRACT FROM AUTHOR]

Orchard floor management in the Rio Negro valley is based on continuous tillage which in the long term may negatively affect soil properties. Therefore, the aim of this research was to evaluate the effect of different soil management treatments in an organic apple orchard (Malus domestica Bork.) cv. Royal Gala on nutrient availability, soil aggregates stability and organic carbon (CO) and total nitrogen (Nt) concentration in soil aggregates in a loamy soil. In March 1999, cover treatments applied to the inter-row spaces were: 1) permanent cover of rescue (Festuca arundinacea) plus alfalfa (Medicago sativa) (A+F): 2) permanent cover of strawberry clover (Trifolium fragiferum) (Tr): 3) seeding of common vetch (Vicia sativa) (V): and 4) control, natural soil vegetation and disking twice in late winter (T). In November 2002, soil samples were taken at three soil depths, 0-7.5; 7.5-15, and 15-30 cm to determine soil organic matter (OM), total nitrogen (Nt), available phosphorus (P) and exchangeable bases (Ca+2, K+ and Mg+2). In the top 0-7.5 cm macro aggregate (100-2.000 µm) micro aggregate (0-100 µm) fractions and the content of OM, OC and Nt were determined. Organic matter and Nt concentration in the perennial cover crops treatments (A+F and Tr) increased, and K+ were higher only in the 0-7.5 cm soil depths respect the V and T treatments. Magnesium concentration increased two-fold in the top 15 cm of soil in A+F compared to T. Calcium concentrations in A+F and Tr were higher than T at all soil depths and for the top 15 cm. respectively. In the T treatment macro-aggregates diminished and micro-aggregates increased due to soil cultivation compared to the perennial cover crops [ABSTRACT FROM AUTHOR]

A leguminous forage centrosema (Centrosema macrocarpum) was planted as a cover crop in a 4 year peach palm plantation (Bactris gasipaes K.) at different increasing rates of phosphorous (P) in order to determine the adequate doses needed to get rapid cover establishment for future use as a silvopastoral system. Four rates of P as rock phosphate were tested: 0, 20 40 and 80 kg/ha. This fertilizer was uniformly sprayed before planting the cover crop at the beginning of the experiment. A randomized complete block design was used to find the response to the different fertilizer rates. The initial levels of soil P were low and increased significantly as a function of the increasing levels of applied P. Similar trends were observed in the tissue of centrosema and peach palm. There was a good P accumulation in the centrosema biomass and nutrient cycling of the soil. The establishment and production of centrosema biomass increased after 150 days of planting in all treatments but the development of centrosema with the rates of 20 kg/ha covered the soil faster and presented greater biomass production than the others. Because there were non significant differences between the establishment rates of P, it is recommended to apply only 20 kg/ha during centrosema establishment. [ABSTRACT FROM AUTHOR]