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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]

In the current Cuban context, local agricultural development is promoted, to achieve territorial self-sufficiency and food sovereignty, where agricultural enterprise require the implementation of information systems that contribute to productive management processes, in order to obtain a more technical elements for decision making. The objective of the work is to develop a web application that contributes to the improvement of the efficiency in the socialization of information. For the diagnosis, an anonymous survey was applied, made up of direct, closed, multiple and unipolar response questions, aimed at decision-makers and managers of agricultural processes. As a development methodology, Scrum, the Domain Guided Design architecture, was used as the Asp.NetCore 3.0 development environment with the C# 8 language and SQL Server database manager mounted on Docker. The result is an "Agricultural Data Analysis System" (SADA) that unifies the services for the dissemination of information, adaptation and rotation of crops and their varieties, where all relevant technical information is recorded and operations are computerized in the same program, to help improve the efficiency of the planning and decision-making processes. The deployment will generate savings of 392.18 CUP for each rotation design. [ABSTRACT FROM AUTHOR]

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It is well known that different soil use and management systems affect the abundance, activity and composition of the soil microbial community. In this work, the behavior of cultivable bacterial populations and, in particular, P (PSB) solubilizing bacteria in soil samples from a long-term trial with different culture sequences was studied. The results obtained show that the clearing and subsequent agricultural use after 11 years generated a decrease in the population of cultivable bacteria in general, and of P-solubilizing bacteria in particular, with respect to the pristine soil. Isolates with high P solubilization efficiency were obtained from the soils from the different rotations. These efficient isolates were taxonomically classified by 16S RNA analysis as belonging to the genera Bacillus, Paenibacillus, Pseudomonas and Xanthomonas. In particular, the characterization of the culture supernatants of the isolates Pseudomonas koreensis and Paenibacillus pabuli showed they are producers of organic acids. The combined inoculation tests of these two strains on maize plants in a culture chamber revealed a synergistic effect on the growth promotion of this species. The results presented here suggest that although PSB populations are more numerous in pristine soils, certain long-term crop rotations favor the increase of more efficient solubilizing bacteria, an aspect that should be considered when designing future search strategies for potential bioinoculants. [ABSTRACT FROM AUTHOR]

Currently, Argentine agriculture is based on a simplified and high-productivity technological model, marked by the trend towards soybean monoculture. These systems with little contribution of carbon (C) to the soil predispose it to its degradation by affecting its physical, chemical and biological properties. In contrast, the crops in the sequence of a rotation differ in the quantity and quality of the stubble they leave in the soil. In the rotation with a higher Fequency of grasses than soybeans, the C balance is positive, while in a rotation with a higher Fequency of soybeans, the balances are negative. The objective of this analysis is to compare the relationship between the areas dedicated to farming soybeans and corn, as an indicator of risk in the reduction of the contribution of C of the crops and of the levels of organic matter of the agricultural soils of the Argentine Republic. The Soybean/Corn Index was calculated From data on official agricultural estimates. The harvested areas of soybean and corn crops were used in each department/municipality of the country and for all campaigns, from 1969/70 to 2020/21. The proposed Index was calculated for three administrative levels: national, provincial and departmental. At the national level, it increased to values close to 6, above the ideal of 1. Although in the last decade this index has been declining, still presents high values in some parts of the country. The analysis at the provincial and department/municipality level was carried out in the three main producing Argentine provinces. [ABSTRACT FROM AUTHOR]

The inclusion of service crops in agricultural rotations has many advantages in terms of resource conservation and sustainability of production systems. Although in Argentina it is a practice in constant increase, in the province of Santa Fe, its implementation is in an exploratory stage. To promote its implementation, the objective of this work is to evaluate, in economic terms, the incorporation of service crops to frequent agricultural rotations in the centre of Santa Fe province. Tree agricultural rotations were compared, with a duration of four years each and different degrees of intensification: two frequent in the area under study and one improvement proposal including Vicia sp. as a service crop and rapeseed (Brassica sp.) for commercial purposes. This comparison was made in economic terms, using the present value method (or updated cash flow) and the cost-benefit ratio of each of the rotations. Sequences were also compared in environmental terms, considering nitrogen and phosphorus balance and carbon sequestration. The results show that, although there are costs associated with the implementation, maintenance and drying of service crop to the rotation, the profitability of the sustainable intensive sequence exceeds the Fequent rotations analysed. In addition, in terms of carbon capture, it is the best performer. The proposed rotation contributes to generating an economic gain with a positive environmental impact, meeting the need for sustainable production. [ABSTRACT FROM AUTHOR]

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The article studies the changes in the agricultural production of the Valencian huerta, one of the largest and most productive orchards in the Mediterranean at the time. Throughout the second half of the 19th century and the first third of the 20th, the crops and rotations that had prevailed for some time were replaced by a new production model. The main change consisted of the relatively rapid disappearance of crops such as mulberry trees and hemp, central to traditional agriculture of the huerta. These textile fibres were displaced by the boom in the production of vegetables, potatoes and onions, while maintaining high-yield wheat cultivation. The change responded to the transformations in the demand for food and the demographic growth of the city of Valencia, which constituted an expanding local market. However, unlike other irrigated areas that supply urban markets, such as the Baix Llobregat and the city of Barcelona, the Valencian orchard also developed export-oriented production lines. Onions, potatoes and tomatoes, above all, found a significant demand in the markets of the United States and Great Britain, where they reached very high export figures. Meanwhile, most of the vegetables were sold in the next city. The new agricultural model was characterized by the diversification of products, the complexity of crops rotations, and the product differentiation based of different internal and external demands. [ABSTRACT FROM AUTHOR]

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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]

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Conservation agriculture is part of the adaptation measures promoted to continue providing food to the world population, while presenting itself as an alternative to mitigate the effects of rice production on climate change. In Cuba, the cultivation of rice is a priority for the Government, and for this reason a strong investment program is carried out with the purpose of replacing imports. Nevertheless, rice is mostly grown in the traditional way (tillage and irrigation by flooding), which implies a high consumption of water and deteriorates the soil, besides that it requires a lot of time, and great energy, economic and environmental costs. However, in a context of climate change, the amount of water available and the low fertility of soils are the main limiting factors in rice production, so the efficient use of water and the improvement of soil fertility determine the future of the crop. In the work we present a review of the experiences developed in Cuba and worldwide with the use of conservation agriculture, focused on saving water and improving water quality, the fertility of the soil, as well as the main steps to follow for its adoption. [ABSTRACT FROM AUTHOR]

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In order to determine the effect of planting density on the morpho-productive traits of Jatropha curcas intercropped with crops under rotation, the following treatments-systems (S) were studied in a completely randomized design: S1 (control): J. curcas at 2,5 x 2,0 m (2 000 plants/ha), S2: 50% of the area with J. curcas at 2,5 x 2,0 m and 50% of the area with crops under rotation (2 000 plants/ha), S3: J. curcas intercropped with crops at 5,0 x 2,0 m (1 000 plants/ha), S4 (control): crops under rotation. To interpret the results of plant height (H), number of primary branches (PB), stem diameter and primary branch diameter, quantity of racemes (NR) and fruit production (FP), a simple classification ANOVA was used and H, PB and NR were correlated; while descriptive statistics was used for the number of fruits per raceme (FR), weight and size of the seeds and crop yield. H and PB were higher for S1 and S2; nevertheless, higher NR was obtained with S3, and this last one did not differ regarding FP (p < 0,05) from the control (S1). There was high and positive correlation (r = 0,84) between H and PB, but they were not correlated with NR. In S3, the yield of the associated crops was 1,023; 4,281 and 0,320 t/ha for beans, sweet potato and sesame, respectively. It is concluded that when using 1 000 plants/ha in association systems, adequate yields and diversity of plant species can be obtained. [ABSTRACT FROM AUTHOR]

The contamination in the water, soil and culture of Allium cepa L. (onion) with metallic trace elements Mn, Fe, Cu, Zn in the Tiabaya countryside, in three study areas (Marshall, Alata and Punke) and a comparative control for water, soil (San José) and onion cultivation "free of contaminants" was evaluated. The metallic trace elements in the water, in time of high flow (avenues) in order of increasing concentration are: Zn

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Copyright of OHM: Obradoiro de Historia Moderna is the property of Universidad de Santiago de Compostela, Servicio de Publicaciones 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.)

In order to evaluate the variation of the groups of the edaphic mesofauna from the application of agroecological methods, a study was conducted in a farm with more than 20 years of establishment in the Artemisa province (Cuba). Previously the farm did not receive organic amendments and it was used as a grazing area for Zebu cattle with a low stocking rate. The area was transformed into three productive systems: 25% of forage, 25% of polycropping and 50% of traditional pastureland, which was designated as control area. The forage area was established in mosaic form, with small plots of perennial crops, and had a periodical supply of organic fertilizers; while the polycropping area integrated a short-cycle crop rotation system, mainly, and compost was applied. The samplings were carried out in the dry and rainy seasons, six and eight years after the transformation. A total of 1 915 edaphic microinvertebrates was collected, belonging to the phylum Arthropoda, represented by two sub-phyla, three classes, two subclasses, six orders and two families. The dominance-diversity curves showed that in the pastureland and in the forage area the fauna communities were more abundant and diverse, and were distinguished by a high dominance of detritivore microarthropods. In the polycropping area no dominant taxa were present. It is concluded that the performance of the edaphic mesofauna was highly dependent on the type of soil management and the seasonality. [ABSTRACT FROM AUTHOR]

Se presenta una serie de resúmenes de trabajos finales de graduación en el campo de la Ingeniería Agronómica, incluyendo uno sobre los genotipos de semilla, uno sobre el efecto de pulgones en plantas y uno sobre la rotación de cultivos.

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Climatic risks imply the probability of occurrence of extreme weather conditions, events that can threaten nature and human activities with a particular pattern of low frequency. They are termed agroclimatic risks when affecting farm production. The aim of this work was to assess an index of agroclimatic risk (ACR), based on the study of soil water clima-tology and simulation of different crop rotation schedules. The ACR index scoring was based on a scale of values running from 0 (minimum risk) to 1 (maximum risk). Four crop rotation schedules, under conditions of dry-land farming, were tested in 21 sites all over the Eastern region of La Pampa province: fallow land - wheat crop (FL-WC), lucerne pas-ture - wheat crop (LP-WC), fallow land - sunflower crop (FL-SC) and winter annual grass pasture - sunflower crop (WP-SC). Maps, generated with information involving the appli-cation for decades of FL-WC, LP-WC, FL-SC and WP-SC rotation schedules, showed the yearly occurrence of partial or absolute droughts during the warm semester. Rotation sche-dule FL-WC exhibited lower ACR values (0.1 to 0.4) than LP-WC (0.1 to 0.6), FL-SC (0.4 to 0.5) and WP-SC (0.4 to 0.5 ). In all cases, ACR index took higher values for the Central-and South-Eastern regions than the North-Eastern region of La Pampa province. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify parasitic nematodes associated with the tomato crop in Leon and Chinandega western region of Nicaragua. During the period of 2010-2011, five tomato fields were sampled in both Leon and Chinandega; these samples included soil and roots, the total sampled area was of 2.5 ha. Eight samples were collected from each of the ten tomato plantations studied, for a total of 80 samples. Soil and root samples were taken 10 m from each other in a zig-zag pattern. Soil nematode extraction was conducted using the Modified Baermann funnel technique and maceration and sieving method was used for root nematodes. The data obtained was correlated with predisposing factors that have been reported to influence nematodes such as soil type, crop rotation and precipitation. Similarly, the population growth of the main nematode genera was described through mathematical models. The greatest densities of nematodes were isolated from soil samples; the most common nematodes in 100 grams of soil were Meloidogyne with 739, Pratylenchus with 555, Tylenchorhynchus with 386 and Helicotylenchus with 252. It was proven that precipitation had no significant effect on the parasitic nematode population. Finally, it was determined that the increasing number of Meloidogyne and Pratylenchus in the tomato crop fit a linear mathematical model (R2=0,98 for both nematodes), showing an existing positive and linear correlation between the phenological stages of the tomato and the increment of the nematodes in the soil. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental 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.)

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Soil organic carbon (CO) content determines many soil functions in the agroecosystem, including nitrogen (N) supply to crops. The level and distribution of organic carbon fractions and mineralizable N in the soil depends on management practices. The aim of this work was to analyze total organic carbon content (COT) associated with the mineral (COA) and particulate (COP) fraction and mineralizable N (through N release during anaerobic incubation, NAN) in whole soil and in macro- and microaggregates under different cropping systems (pastures and cropping with conventional tillage (LC) and with no-tillage (SD)) and N fertilization (0 and 120 kg N ha-1). Soil samples were taken from a long-term crop rotation and tillage system trial at Balcarce, Buenos Aires province. Macro- and microaggregates were separated by dry sieving and COT, COA, POC, and NAN content were determined in whole soil and in each aggregate fraction. The soils under pasture showed the highest CO fraction and NAN content both in whole soil and in each of the aggregate fractions. The longer the period under cropping and LC, the lower the variables compared with the SD regime. Although the proportion of macro- and microaggregates did not vary among treatments, a significant correlation was found between COT and POC content in macroaggregates and their stability when soil was less disturbed (pastures and SD). Under LC, aggregate stability was lower and there was no correlation with CO content. Under cropping there was a significant correlation between NAN in whole soil and NAN in the macroaggregates. A higher expression of N mineralization potential can therefore be expected in soils under management techniques that tend to break up macroaggregates or where these are less stable. However, the lack of significant differences in aggregation and in NAN and CO fractions under cropping suggests that careful tilling can help N mineralization largely without affecting its properties and that the inclusion of pastures in the rotation would reverse the effect of cropping. [ABSTRACT FROM AUTHOR]

Se evaluó el crecimiento y desarrollo de la canavalia (Canavalia ensiformis) y se determinó su influencia en conjunto con fertilización mineral y la inoculación con hongos micorrízicos arbusculares (HMA), cepa Glomus hoi like (Berch & Trappe), en el funcionamiento micorrízico, el suministro de nutrientes y el rendimiento del maíz (Zea mays). El suelo empleado fue un nitisol ródico éutrico. Se utilizó un diseño experimental de bloques al azar con cuatro réplicas. Se evaluaron cuatro tipos de rotaciones: canavalia o barbecho precedentes del maíz y la inoculación de este cultivo con HMA. En cada rotación se compararon cinco dosis de fertilizante mineral nitrogenado (0, 50, 100, 150 y 200 kg de N/ha). Con respecto al barbecho, canavalia incorporó una cantidad mucho mayor de masa seca y nutrientes, debido al aporte por fijación biológica del nitrógeno (FBN). El número de esporas de HMA aumentó con la incorporación de canavalia al suelo. Se obtuvieron rendimientos significativamente mayores en las rotaciones donde se incorporó canavalia y se inocularon cepas efectivas de HMA. La presencia del abono verde hizo que disminuyera la dosis mínima de nutrientes, de 129 kg de N/ha a 100 kg de N/ha, necesaria para lograr el rendimiento máximo estable. Esta dosis disminuye aún más (50 kg de N/ha) en presencia de cepas efectivas de HMA. [ABSTRACT FROM AUTHOR]

Rice monoculture affects soil fertility, helps pest development, causes salinization and declines yields after three consecutive harvests. Thus, holding back such effects is strategic; the special agronomic rice management inexorably damages its agronomic qualities. Outlining a possible solution to the problem, the present paper summarizes the main results of a sustainable management in the rice-growing areas from "Los Palacios" Rice Experimental Station, where 31 alternatives were tested in seven crop rotation systems, besides a survey performed in Caribe farm from "Los Palacios" agro-industrial rice complex. It was proved that rice monoculture impoverishes soil physical and chemical fertility whereas crop rotation allows recovering lost fertility and achieving stable and sustainable productions. Also, the work shows it is possible to establish a sustainable rice-growing area. [ABSTRACT FROM AUTHOR]

The objectives of this study, were: a) to characterize the soil mechanical penetration resistance (RST) variation in the 0 to 20 -cm depth of two rotation treatments with and without cattle grazing and b) to determine the RST relationship with soil water content (W). The experiment took place on a Typic Haplustoll in SW Buenos Aires province, on sunflower-wheat based rotations. Treatments included: a) 100 % cash-crop rotation with no cattle grazing and b) Mixed rotation, including an oat forage crop with direct grazing by 350 to 400 kg steer at a 25 head/ha stocking rate between wheat and sunflower crops. RST and W were determined on ten opportunities near planting dates. After oat grazing, RST was higher in the Mixed rotation compared to the crop rotation in the 0 to 20 cm soil layer, with greater differences in the 2.5-7.5 cm layer. Corrected to a W of 190 g kg-1, the RST in the crop rotation showed an increasing linear trend over time. RST for the mixed rotation fitted a quadratic model which tended to stabilize at 2.5 MPa. In addition, the mixed rotation showed a second variation pattern related to sample dates: RST after grazed oats was higher than at the end of the oat-sunflower-wheat cycle. This decrease was attributed to a recovery of bioporosity due to the crop roots effect on the soil. Observed RST values were close or higher than those considered critical for root penetration in 20 and 50% of sampling dates for the crop and mixed rotations, respectively. [ABSTRACT FROM AUTHOR]

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Oilseed rape poses a higher sulfur (S) demand, compared to other crops. This may indicate that the inclusion of this crop in the crop rotation could accelerate soil S depletion. In this work, we compared the allocation of biomass, nitrogen (N), phosphorus (P) and S in oilseed rape mature plants. Two factors were analyzed in a field experiment: nitrogen and sulphur (two levels for each factor). At harvest, we measured the accumulation of biomass, N, P and S in three compartments: roots, straw and grains. Yield was little affected by the addition of single nutrients but the simultaneous addition of N and S caused a 56% increase in this parameter. Nitrogen and P showed a rather similar allocation pattern. Sulfur, conversely, showed a lower allocation to grains and a higher allocation to straw than the other two studied nutrients. The lower allocation to the harvested organ would attenuate the effect of the high demand of S of this crop on the nutrient balance and would also allow a re-utilization of the S fertilizer by the following crop. [ABSTRACT FROM AUTHOR]

In this work, we compared two methods of available phosphorus evaluation, Bray & Kurtz I, (the most common in the pampean zone), and Mehlich III, (commonly used in other countries in soils with contionuous P applications). The studied soils received increasing doses of phosphate fertilizer, applied to the beginning of a maize, wheat and soybean rotation. Soil samples were taken in the field, and extractable phosphorus (P) by Mchlich III and Bray & Kurtz I methods were compared. The data were adjusted with the Peto-Wilcoxon test of determination and regression analysis to evaluate the sensitivity of both methods. The results indicated that to low values, these are not different substantially, but from the 15 (rag kg-1) of P in soil, the Mehlich III method overestimates the value with respect to Bray & Kurtz I. This method was the one that showed greater variation to the added doses of P, showing greater sensitivity between treatments. It was concluded that the Bray & Kurtz I method is the one that better adapts to the practices of diagnosis and recommendations of fertilizer use. [ABSTRACT FROM AUTHOR]

The growing of banana the same as papaya, in the western region of the country, are strongly attacked by pests, because of this, plantations don't last more than a cropping cycle. To plant de same area yearly with the same crop favour the setting on the soil of parasites that can be removed with crop rotation. This paper shows the experimental results of two years of work with crop rotation grow in two high density plantation 4x2x1 m ahd 3x1 m with a density of 3333 plants/ha irrigated with drips. Yields of 40,37 t/ha were obtained in banana, while in papaya yields were of 71,42 t/ha; with a benefit - cost relation of 1,15, internal returning rate of 36,27 %, a net value of 21,47 and the recovering time is 3,01 years. [ABSTRACT FROM AUTHOR]

The effect of preceding crop residue characteristics on N availability for wheat (Triticum aestivum L.) may mask the changes in soil capability to provide N due to management. Preceding crop effects should be taken into account to diagnose N fertility. The aims of this work were to evaluate i) wheat relative (to the maximum obtained in the corresponding experiment and year) yields (RR) and aboveground dry matter (MSR) and N accumulation (NR) in time after different preceding crops, and ii) the relationship between RR, MSR and NR variation and soil organic matter content changes. In two long term crop rotation experiments at Balcarce (on a complex of Typic Argiudoll and Petrocalcic Paleudoll) the variation of RR, MSR and NR along years under cropping with conventional tillage, was analyzed. The preceding crops were potato (Solanum tuberosum L.), soybean (Glycine max L. Merr.), wheat, sunflower (Helianthus annuus L.) and maize (Zea mays L.). All three variables showed a decrease along cropping years, but up to different levels according to which had been the preceding crop. Residue characteristics and/or the way they had been managed before wheat seeding made that RR, MSR and NR after soybean, potato and wheat were higher. On the other hand, wheat RR, MSR, NR after maize were the lowest. These effects were associated with the role of residues on N mineralization-immobilization cycle. In general, the variation in wheat RR, MSR and NR along cropping years was not associated with changes in soil organic matter due to soil management under cropping. The short term effect of preceding crop residues and of its management on N dynamics defined the amount and timing of the availability of N for wheat. This was independently of the effect of the rotation on the capability of the soil to mineralize N due to how the residues intervene on the cycle mineralization-immobilization. [ABSTRACT FROM AUTHOR]

El análisis de los sistemas de producción de leche necesita de un enfoque integral y multidisciplinario, debido a que en estos interviene un conjunto de factores que no se pueden analizar de forma aislada y en los que la relación suelo-planta-animal-clima-hombre es muy compleja y variada. Las potencialidades que de ellos se puede esperar dependen del clima, del suelo, de la especie botánica, del uso de insumos, del manejo y del tipo de animal utilizado, entre otros factores. El objetivo del presente trabajo fue describir y analizar los principales resultados en la evaluación, manejo e integración de diferentes especies de pastos, forrajes y alimentos locales en los principales sistemas de producción de leche existentes en el país. Existen diferentes formas de clasificar los sistemas de producción de leche cuando la base de la alimentación es a partir de gramíneas, leguminosas herbáceas y plantas de ramoneo, en los cuales se han tenido en cuenta: el sistema de explotación (intensivo o extensivo); el tiempo dedicado al pastoreo (estabulado, restringido o libre) y el tipo de recurso forrajero (herbáceo y arbóreo). En cada forma de clasificación se ofrecen los principales resultados en términos de carga, especies forrajeras utilizadas, potencial de los animales y rendimientos en producción de leche con el uso o no de fertilizantes y riego. De acuerdo con la forma de manejar la rotación se presentan resultados sobre el pastoreo racional Voisin con altas cargas instantáneas. Aparece un análisis de cómo ha cambiado el paradigma en el manejo del monocultivo de gramíneas y se ofrecen interesantes resultados en el manejo de multiasociaciones con diferentes gramíneas y leguminosas herbáceas y arbóreas, sin riego ni fertilización. Se concluye que los sistemas intensivos con riego y fertilización en gramíneas mejoradas son una opción en animales de alto potencial lechero que justifiquen la inversión y no afecten el medio ambiente. También se plantea que la combinación de especies herbáceas y arbóreas en sistemas de producción contribuye a conservar la biodiversidad vegetal y animal, pues tienen un impacto positivo en la productividad del suelo y el estrés climático, por el efecto beneficioso de la sombra en la temperatura, la composición bromatológica del estrato herbáceo, el incremento de controles biológicos, la materia orgánica y la biota edáfica, que inciden en las respuestas productivas del sistema. [ABSTRACT FROM AUTHOR]

In "Los Palacios" Rice Research Station from the National Institute of Agricultural Sciences (INCA), within 1999-2001 period, the present work was developed under a Randomized Block design with four repetitions, where two new agroecological practices as an alternative solution were proved to chemically control red rice. The annual rice-sunflower rotation was common to both practices; after sunflower cultivation, the soil was subjected to a different management to diminish red rice seed reserves. One treatment was dry farming encouraging germination and removing plants. The other one was flooding soil for 30 days, encouraging germination and preparing the soil by the continuous mud technology. Results were compared with the soil management given to productive practice, consisting of: chemical disinfection and preparation without controling red rice. The rice-sunflower rotation and dry soil farming eliminated more than 98 % of the mixture and increased commercial rice yield from 1.1 to 5.1 t·ha-1. Profits surpassed 1 200.00 pesos·ha-1. [ABSTRACT FROM AUTHOR]

This experiment was carried out in the Allelopathic Laboratory of Research Agriculture Center, with the objective to know the allelopathic effect of Sorghum aqueous extracts on germination and growth of crops. Aqueous extract from leaves more steam residues at 50, 75, 100 % and blanc were tested on germination and growth of rice (Oriza sativa L.), maiz (Zea maiz L.), sesame (Sesamum indicum L.), squash (Cucurbita moschat Duch.), bean (Phaseolus vulgaris L.) and radish (Raphanus sativus L.) on laboratory controlled conditions (Petric disc). Inhibitory effect on crops germination was shown by extracts, with exception of bean and rice crops; the inhibitory effect on growth of root and steam of all crops tested were shown, for that reason the allelopathic effect of sorghum it would be to take account to development association and rotation of crops, main with squash, rice and bean. [ABSTRACT FROM AUTHOR]

The intensification of conventional agriculture in the southeastern Buenos Aires province (Argentine) produced soil fertility degradation. No-tillage (SD) agriculture and the inclusion of pastures (PP) in crop rotations, represent management alternatives to reduce conventional tillage (LC) effects. A lab experiment was carried out with the aims of: a) to study nitrogen mineralization (TMB), nitrification (TNB) and consumption (TCB) gross rates in a Mollisol under LC, SD and PP; and b) to quantify the potentially mineralizable nitrogen through anaerobic incubation (NAN) and its relation with mineralization rates. The studied soil was a Typic Argiudoll - Petrocalcic Paleudoll complex which had been under conventional tillage for 17 yr until 1994 when it was converted to three different soil management systems: continuous PP and continuous cropping under SD, and under LC. Gross processes were estimated through the 15N dilution technique, adding 15N-labeled (NH4),SO4 (10% 15N at. exe.) four times during an 35-d incubation period and NAN was determined through short anaerobic incubations. Gross N mineralization rates ranged between 0.17 and 1.36 mg N kg-1 day-1. The soil under PP treatment presented higher TMB than cropping managements. Gross consumption rates ranged between 0.47 and 3.21 mg N kg-1 day-1, being nitrification the most important consumption process for all three management systems (80%). Cumulative mineralized N (P= 28.6 mg kg-1, SD= 19.7 mg kg-1 and LC= 10.8 mg kg-1) was different among management systems, whereas cumulative consumed N were not (P= 72.6 mg kg-1, SD= 56.9 mg kg-1 and LC= 74.1 mg kg-1). The soil under PP presented highest NAN values (93.4 mg kg-1) that was twice as much as soil under LC (41.4 mg kg-1) or SD (46.6 mg kg-1). Lineal correlation coefficients between TMB and NAN were statistically significant for all the measurement times and ranging between 0.47 and 0.97. After five years from management installation, PP produced an increase in TMB relative to the cropping managements, whereas the same period under SD did not improve the TMB relative to LC. Gross consumption rates did not present differences among management systems and neither PP nor SD improved TNB respect to LC. [ABSTRACT FROM AUTHOR]

Since many years ago, a few group of citric Enterprises have been working in the organic citrus production (Ceiba, Moron, Arimao) in which is necessary to mechanize the process of distribution of big volumes of organic matter. Taking in consideration the high delivery norms (12 t/ha) that implies the delivery of 3 tn/row and 600 t/year, it becomes necessary the study of spreaders with great capacity, resistance and durability, besides satisfying the distribution demands in citrus plantation, mainly because the organic matter distribution under the branches of the trees is required in a continuous band of wide greater than 0,5m (38,46 kg/tree). The effectiveness of the execution of these norms is opposed with the effects of compacting of the soil, mainly when the streets of plantations is planted of other cultivations with short cycle like leguminous and others. The work has the objective of analyse the advantages and disadvantages that are present in the industrial spreaders machines, according to the new conditions that organic citrus fruits demands. Therefore, the parameters: delivery capacity, volume of the hoppers, compacting of the soil, wide of distribution, effectiveness of distribution mechanisms, lateral delivery to low height and above the leguminous ones, they constitute the main selection elements. In the analysis it is considered the economic factor as decisive element in the selection of the best options. Of the analysis you concludes that a device adapted to the end of a spreader machine is needed with varied mechanism of the height distribution, to achieve different launching conditions. [ABSTRACT FROM AUTHOR]

In the southeastern Buenos Aires Province (Argentina) unsuitable combination of crop rotation and tillage systems (cropping systems, SC) has reduced soil organic matter content. Our aim was to evaluate the efect of seven SC in a long term experiment (since 1976) started in 1994: permanent pasture (PP), permanent cropping under no tillage (SD) (SD100) and conventional tillage (LC) (LC100), cropping-pasture rotation (50% - 50% of time (3 yr each)) under SD (SD50) and LC (LC50), cropping pasture rotation (75% - 25% of time (6 and 3 yr)) under SD (Sr) 75) and LC (LC75); and two N fertilization rates: 0 and 120 kg N ha-1, on total (COT) and particulate (COP) organic carbon, for 0-20 cm depth in 1994 and for 0-5 cm, 5-20 cm and 0-20 cm depths in 2003. In 1994 COP and COT showed the effect of previous management of different crop rotations under LC, and the shortest the cropping period, the highest COP and COT. In 2003, there were no differences among SC in COT at 5-20 and 0-20 cm depths. At 0-5 cm depth differences were not clear, but PP, LC50 and SD50 (under pasture until sampling) did not differ among them and had COT greater than the other SC. Particulate organic carbon was highest under PP, SD50 and LC50 either at 0-5 and 0-20 cm depths. At 0-5 cm depth there were not differences between SD75 and SD 100 nor between LC75 and LC 100, although COP under SD was significantly greater than under LC, showing a trend to decrease with cropping years. This difference between tillage systems was not observed at 0-20 cm depth. At 5-20 cm depth, we found unclear differences in COP between SC, although decreasing with cropping years. Total organic carbon was greater at all depths in those plots that had received 120 kg N ha-1, respect to those unfertilized, although not significantly. At 5-20 and 0-20 cm depths, fertilization produced significantly higher COP than without it. Variation between 1994 and 2003 at 0-20 cm depth showed significant differences in COP and COT. There were not differences neither between increases of COP in those SC under pasture in 2003 nor between them and those under SD. On the other hand, relative variation of COP, especially at 0-5 cm depth, was higher than the relative variation of the other variables. It is concluded that short cropping-pasture rotations (50% and 50% of time), SD and N fertilization improve COT and COP and it has been demonstrated the beneficial effect of such practices. For the conditions of this experiment, COP has been a more sensitive indicator than COT, and it would be able to detect management practices effects. [ABSTRACT FROM AUTHOR]

Root-Knot Nematodes (Meloidogyne spp.) are one of the most important pests in vegetables that grow under greenhouses and shelter conditions with plastic materials, tissues or other kinds. Several alternatives have been successfully used in the world in this type of instalations. Tactics like solarization, biofumigation, grafting, crop rotation, chemical pesticides and biological control agents are part of the Integrated Pest Management Sistems in tunnels and greenhouses in Spain, Italy, Greece, France, Israel and China, among other countries. The international tendency is guided towards the combination of several tactics like solarization, biofumigation and the use of resistant varieties. In this paper, the authors show their considerations about the possibilities of using these tactics in Cuba, and the necessity of our country to make a research in order to know the effectiveness of several tactics under Cuban conditions (temperature, type of soils, nematode populations, among others.). [ABSTRACT FROM AUTHOR]

The experiment was carried out in a tunnel of sheltered cultivation system at the National Center for Animal and Plant Health. A crop rotation scheme using pack chard -- lettuce (used as trapping crop) -- cabbage -- tomato was used. The last crop is the principal in this area. Root-knot nematode populations were reduced from 20 -30 J2/cm³ soil to 2-3 J2/cm³ and the presence of mixed populations of Meloidogyne incognita and M. arenaria was detected in the same cultivation area. The first population was predominant in tomato and lettuce roots and the second in pack chard and cabbage roots. [ABSTRACT FROM AUTHOR]