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Background and Objectives: Background and objectives: Agriculture has always struggled with weeds throughout history and has achieved considerable progress in this regard. Weeds compete with agricultural plants to receive nutrients, soil moisture and sunlight and lead to a decrease in the yield of agricultural plants. Due to its slow growth in the rosette stage, the safflower plant is very vulnerable to the competition of weeds, and weeds can severely reduce the yield of safflower and even cause the loss of the entire crop. Therefore, eliminating the competition of weeds is effective in increasing its performance. Manual weed control is timeconsuming and expensive. Chemical weed control method is one of the important methods used in weed control. But these herbicides can have a serious impact on the environment. Non-chemical weed control such as the use of mulch and cover plants are the preferred methods for weed control. Considering the importance of weed control and the existence of few studies on the comparison of different safflower weed control methods, this experiment was conducted with the aim of comparing the effect of different weed control methods in safflower fields. Materials and Methods: In order to investigate the effect of different weed control methods on oil percentage and yield in safflower plant, an experiment was conducted in the form of a randomized complete block design with 12 treatments and four replications in the research farm of the Faculty of Agriculture of Tabriz University located in the Khilat Pushan research station in the area near Basmanj. Preparation and planting of safflower seeds was done in the middle of April. Weed control operations were carried out according to different weed control treatments. After the physiological treatment, the harvesting operation started and after removing the side rows of each plot, 10 samples were taken from the middle row by removing 0.5 meters from the margins and separately for each plot, they were taken to the laboratory for the necessary measurements. Results: In this research, V. Ervilia had an increase of 33.5 and 40.5 percent on the dry weight of the stem of safflower. Also, in the two treatments of manual weeding twice before the stem lengthening and complete manual control of weeds, the length of the secondary branches of safflower (C. tinctorius) was 35 and 35.5 cm, respectively, which is 38.6 and 32.6 percent compared to the absence of weed control. In this research, in the treatments of V. ervilia cover plant, V. ervilia cover plant and a combination of V. ervilia cover plant and V. ervilia cover plant, biomass produced 1.69, 1.73 and 2.32 tons, respectively, which can in addition to control Weeds and improving safflower yield are of economic importance. Conclusion: The results of the study showed that the control of weeds in the safflower field in the early stages of growth is more effective than in the more advanced stages, and it can indicate the sensitivity of safflower to the competition of weeds in the early stages of safflower growth. In addition to that, the treatments of V. ervilia, V. ervilia and V. villosa, the use of trifluralin herbicide, trifluralin + phenmedipham herbicide, trifluralin + Haloxyfop-R-methyl and two manual weeding before the stem elongation also had a significant increasing effect on the harvest index and this trait compared to the control, it increased significantly. [ABSTRACT FROM AUTHOR]

The objective of this study was to fit the Logistic growth model for plant height and number of nodes of two buckwheat cultivars at sowing times, as well as comparing the cultivars and sowing times. Twenty uniformity trials were carried out, formed by the combination of two buckwheat cultivars (IPR91-Baili and IPR92-Altar), sown at five times, for two consecutive years. Evaluations were carried out twice a week throughout the vegetative stage until the end of flowering. In each evaluation, five plants were randomly collected from each trial to measure plant height and count the number of nodes on the main stem. The logistic model was fitted with the values of the five plants of each evaluation. Model parameters were estimated, as well as their respective confidence intervals. The goodness of fit of the model was assessed through the coefficient of determination, Akaike information criterion, and residual standard deviation. The plant height and number of nodes of buckwheat, cultivars IPR91-Baili and IPR92-Altar, were described by the Logistic model. The Logistic model satisfactorily describes the growth of buckwheat plants, and a specific fit considering each cultivar and sowing time is needed. [ABSTRACT FROM AUTHOR]

ABSTRACT The objective of this study was to fit the Logistic growth model for plant height and number of nodes of two buckwheat cultivars at sowing times, as well as comparing the cultivars and sowing times. Twenty uniformity trials were carried out, formed by the combination of two buckwheat cultivars (IPR91-Baili and IPR92-Altar), sown at five times, for two consecutive years. Evaluations were carried out twice a week throughout the vegetative stage until the end of flowering. In each evaluation, five plants were randomly collected from each trial to measure plant height and count the number of nodes on the main stem. The logistic model was fitted with the values of the five plants of each evaluation. Model parameters were estimated, as well as their respective confidence intervals. The goodness of fit of the model was assessed through the coefficient of determination, Akaike information criterion, and residual standard deviation. The plant height and number of nodes of buckwheat, cultivars IPR91-Baili and IPR92-Altar, were described by the Logistic model. The Logistic model satisfactorily describes the growth of buckwheat plants, and a specific fit considering each cultivar and sowing time is needed.

Weeds are the most important limiting factors in agricultural systems and the use of mulch is considered as a suitable solution in the ecological management of weeds. In order to evaluate the coriander yield and its weed control, a factorial experiment was conducted at the research farm of the Faculty of Agriculture, University of Zanjan in 2020. The first factor was the types of mulches including ratios of 100 % (40.0 kg ha-1), 66 % (26.4 kg ha-1), and 33 % (13.2 kg ha-1) of clover (Trifolium alexandrinum L.) and 100 % (20.0 kg ha-1), 66 % (13.2 kg ha-1), and 33 % (6.6 kg ha-1) of alfalfa (Medicago scutellate L.) as living mulches, wheat straw (Triticum aestivum L.) (one kg m-2) as a non-living mulch, and a non-mulched treatment and the second factor was weed control including complete weed control, once-weed control and non-weed control. The results showed that the effects of the treatments of mulch type and weed control were statistically significant on the components of yield and yield of coriander. The highest grain yield (1601.4 kg ha-1), biomass yield (3901.0 kg ha-1) and essential oil yield (3.35 kg ha-1) were recorded in wheat straw mulch under complete weed control conditions. Clover at densities of 100 % and 66 % caused suffocation and complete destruction of coriander plants. Therefore, the grain yield and biomass production of coriander in these treatments were equal to zero. Alfalfa at low densities had no significant effect on weed control. Complete control of weeds caused a significant increase in all evaluated traits in coriander. The results of the present study showed that wheat straw mulch is a suitable solution for controlling coriander weeds, which not only does not interfere with the growth of coriander but also causes effective control of its weeds. Therefore, considering the importance of integrated control of weeds in sustainable agricultural systems, the use of wheat straw mulch can be introduced as one of the strategies to reduce the use of chemical pesticides and reduce environmental pollution. [ABSTRACT FROM AUTHOR]

The input of organic matter in the soil by the no-tillage system (NTS) increases as the system becomes established, raising the levels of organic phosphorus (P) and reducing the P soil adsorption. This study evaluated the availability of organic and inorganic P in areas under different management systems and stages of adoption in the Cerrado. The data were analyzed as a completely randomized design, corresponding to: (1) an NTS after 5 years of its implantation (NTS5); (2) an NTS after 17 years of its implantation (NTS17); (3) a conventional tillage system more than 20 years old (CTS); (4) Native Cerrado (NC). There were five repetitions for all treatments. Depths of 0–5 and 5–10 cm were evaluated for the available P (P-avail), remaining P (P-rem), organic P (oP), and inorganic P (iP) forms extracted with Sodium bicarbonate (NaHCO3) (P-avail), Sulfuric acid (H2SO4) (moderately labile), and Sodium hydroxide (NaOH) (moderately resistant). The P from the sequential extractions accumulated at a depth of 0–5 cm, mostly in the organic form in the NTS17 and NC areas, demonstrating the contribution of the NTS to the conversion of the P reserve in the soil. The CTS treatment greatly accumulated P, especially in the inorganic form, indicating the non-conservationist characteristic of this system. The oP and iP contents in the soil were not affected by age of the NTS, which was similar to the NC. Our results show that the continuous input of organic matter deposited on the soil surface in the NTS17 increased the levels of organic and inorganic P, consequently providing greater availability of P in the soil for cultivated crops. [ABSTRACT FROM AUTHOR]

Copyright of Biotechnologie, Agronomie, Societe et Environnement is the property of Les Presses Agronomiques de Gembloux 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 study aimed to evaluate the occurrence of mycorrhizal fungi and glomalin content in soil under different cover crops with and without the application of nitrogen in the cover. The following cover plants were used: Crotalaria juncea (Crotalaria juncea L.), wild beans from Ceará (Canavalia brasiliensis Mart. ex Benth.), Guandú 'BRS mandarin' [Cajanus cajan (L.) Millsp.], millet 'BR05' [Pennisetum glaucum (L.) R.Br.] and sorghum 'BR 304' [Sorghum bicolor (L.) Moench]. The absolute control of the experiment was the treatment without the use of cover crops, that is, the vegetation of spontaneous occurrence in the area. The experimental design was randomized blocks in subplots with three replications. Spore density, mycorrhizal colonization rate, easily extractable glomalin, and species present in the rhizosphere of the cover crops were determined. No differences were found in the diversity of mycorrhizal fungi associated with the different cover crops studied or in the values of spore density, root colonization, or glomalin content. Nitrogen application did not influence the mycorrhizal activity in the investigated cover crops. The most frequent species associated with cover crops were Scutellospora pellucida and Scutellospora persica in C. juncea; Gigaspora sp. on Sorghum; Glomus macrocarpum in Guandu; G. macrocarpum and Glomus clavisporum in millet; and Glomus microaggregatum and Glomus tortuosum in Spontaneous Vegetation. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the occurrence of mycorrhizal fungi and glomalin content in soil under different cover crops with and without the application of nitrogen in the cover. The following cover plants were used: Crotalaria juncea (Crotalaria juncea L.), wild beans from Ceará (Canavalia brasiliensis Mart. ex Benth.), Guandú ‘BRS mandarin’ [Cajanus cajan (L.) Millsp.], millet ‘BR05’ [Pennisetum glaucum (L.) R.Br.] and sorghum ‘BR 304’ [Sorghum bicolor (L.) Moench]. The absolute control of the experiment was the treatment without the use of cover crops, that is, the vegetation of spontaneous occurrence in the area. The experimental design was randomized blocks in subplots with three replications. Spore density, mycorrhizal colonization rate, easily extractable glomalin, and species present in the rhizosphere of the cover crops were determined. No differences were found in the diversity of mycorrhizal fungi associated with the different cover crops studied or in the values of spore density, root colonization, or glomalin content. Nitrogen application did not influence the mycorrhizal activity in the investigated cover crops. The most frequent species associated with cover crops were Scutellospora pellucida and Scutellospora persica in C. juncea; Gigaspora sp. on Sorghum; Glomus macrocarpum in Guandu; G. macrocarpum and Glomus clavisporum in millet; and Glomus microaggregatum and Glomus tortuosum in Spontaneous Vegetation.

ABSTRACT For its production, broccoli requires large quantities of nutrients in relatively short periods. As a conservation technique, the no-tillage planting of broccoli over the pearl millet straw in succession may interfere with the dynamics of nutrient release, inflorescence production and the chemical attributes of the soil. The objectives of this work were to evaluate nutrient cycling, broccoli production and soil chemical attributes in a no-tillage system in succession to pearl millet for two consecutive years. The treatments consisted of pearl millet (BRS 1501) with the straw maintaned whole over the soil, pearl millet with the ground straw, spontaneous plants with biomass maintaned on the soil and conventional system with soil tillage without cover maintenance. It was found that ground pearl millet on the soil surface intensifies the nutrients release rate and provides a less use by broccoli grown in succession. The continuous conventional system reduces the absorption of nutrients and the production of inflorescence of broccoli grown in highly-fertile soil. Pearl millet is efficient in maintaining potassium levels in the soil over broccoli crops in succession. The maintenance of whole pearl millet straw on the soil surface is a promising technique for growing broccoli in succession.

The input of organic matter in the soil by the no-tillage system (NTS) increases as the system becomes established, raising the levels of organic phosphorus (P) and reducing the P soil adsorption. This study evaluated the availability of organic and inorganic P in areas under different management systems and stages of adoption in the Cerrado. The data were analyzed as a completely randomized design, corresponding to: (1) an NTS after 5 years of its implantation (NTS5); (2) an NTS after 17 years of its implantation (NTS17); (3) a conventional tillage system more than 20 years old (CTS); (4) Native Cerrado (NC). There were five repetitions for all treatments. Depths of 0–5 and 5–10 cm were evaluated for the available P (P-avail), remaining P (P-rem), organic P (oP), and inorganic P (iP) forms extracted with Sodium bicarbonate (NaHCO3) (P-avail), Sulfuric acid (H2SO4) (moderately labile), and Sodium hydroxide (NaOH) (moderately resistant). The P from the sequential extractions accumulated at a depth of 0–5 cm, mostly in the organic form in the NTS17 and NC areas, demonstrating the contribution of the NTS to the conversion of the P reserve in the soil. The CTS treatment greatly accumulated P, especially in the inorganic form, indicating the non-conservationist characteristic of this system. The oP and iP contents in the soil were not affected by age of the NTS, which was similar to the NC. Our results show that the continuous input of organic matter deposited on the soil surface in the NTS17 increased the levels of organic and inorganic P, consequently providing greater availability of P in the soil for cultivated crops.

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.)

Understanding the dynamics of decomposition and release of nutrients from plant residues of different covers, in association or succession, is essential to define more sustainable management strategies in tropical soils. The objective of this study was to estimate the decomposition rates and the release of nutrients during the decomposition of different crop residues with different chemical compositions when in association (Mix) or in succession as residue management. A study was carried out with the respective treatments in a (2 × 6) + 1 factorial scheme: (a) without and with the addition of Pennisetum americanum residue (L); and (b) six residue crops (legumes and non‐legumes) and one additional treatment with residue of millet only; with destructive samples over time (0; 0.08, 0.25 and 0.41 years after incubation). The treatments were distributed in a randomized block design with four replicates. The plant material was processed, and the contents of macro‐ and micronutrients were determined. The decomposition rates and release of nutrients from the residues were estimated by fitting nonlinear regression models. Residues of only non‐legumes, with the exception of sunflower, tend to accumulate and degrade more slowly, resulting in a slow release of nutrients to the soil. Legume residues are more easily decomposed, enabling faster delivery of the nutrients available to the soil. Despite the faster degradation of legume residues, brown hemp was more resistant to decomposition. A combined supply of legume and non‐legume residues favoured a diversified pattern of decomposition and release of nutrients among the different residues studied. The knowledge of the biochemical composition, as well as the dynamics of decomposition and release of nutrients from leguminous and non‐leguminous residues, will directly influence the management to be adopted and the functionality of the residues in the soil. Highlights: Decomposition of associated plant residues as soil fertility management strategies for tropical soil were explored.Interactions of decomposition dynamics of plant residues applied to tropical soils were investigated.The combined supply of legume/non‐legume residues favours greater decomposition and release of nutrients.Biochemical composition of plant residues directly influences the sustainable soil fertility management strategies to be adopted. [ABSTRACT FROM AUTHOR]

The biomass production by cover plants provides soil protection against erosion and weed control in the winter period, while the effect of cover crops on the parameters of physical soil quality helps in root growth and water storage. The objectives of the present study were to evaluate the influence of winter plants on the physical quality of the soil. The experiment consisted of unifactorial treatments, composed of different winter plants: vetch (Vica sativa L.), forage radish (Raphanus sativus L.), black oat (Avena strigosa Schreb.), rye (Secale cereale L.), wheat (Triticum aestivum L.) and control treatment. The experimental design was randomized blocks, with four replications per treatment. The parcels consisted of 34 lines implanted with a disc seeder and spaced 17 cm and 10 m long, comprising an area of 57,80 m² per parcel. Sowing densities were 40 kg ha-1 for vetch, 20 kg ha-1 for forage radish, 60 kg ha-1 for rye, 150 kg ha-1 for wheat and 90 kg ha-1 for black oat. The control treatment consisted of the vegetation that emerged spontaneously. The parameters evaluated were plant green mass, weed occurrence, apparent density, gravimetric moisture and soil penetration resistance. With the vetch cultivation there was a reduction in the density of the soil in its surface layer, compared to the control treatment and the other cover crops. Wheat increased gravimetric soil moisture retention. Forage radish was superior to the other cover crops in terms of biomass production, totaling 59.91 t ha-1, as well as being the only cover crop that reduced soil penetration resistance, in the layer from 0 to 40 cm of ground. Vetch reduced the density of the soil in its surface layer, and also the resistance to penetration, from 21 cm of depth. Compared to the control treatment, cover crops were efficient in suppressing weed growth. [ABSTRACT FROM AUTHOR]

For its production, broccoli requires large quantities of nutrients in relatively short periods. As a conservation technique, the no-tillage planting of broccoli over the pearl millet straw in succession may interfere with the dynamics of nutrient release, inflorescence production and the chemical attributes of the soil. The objectives of this work were to evaluate nutrient cycling, broccoli production and soil chemical attributes in a no-tillage system in succession to pearl millet for two consecutive years. The treatments consisted of pearl millet (BRS 1501) with the straw maintaned whole over the soil, pearl millet with the ground straw, spontaneous plants with biomass maintaned on the soil and conventional system with soil tillage without cover maintenance. It was found that ground pearl millet on the soil surface intensifies the nutrients release rate and provides a less use by broccoli grown in succession. The continuous conventional system reduces the absorption of nutrients and the production of inflorescence of broccoli grown in highly-fertile soil. Pearl millet is efficient in maintaining potassium levels in the soil over broccoli crops in succession. The maintenance of whole pearl millet straw on the soil surface is a promising technique for growing broccoli in succession. [ABSTRACT FROM AUTHOR]

Carbon and nitrogen from the soil microbial biomass play a significant role in the rotation of C and N, and promote nutrient cycling. Thus, the objective of this study was to evaluate changes in the soil microbial biomass with growing doses of cover plant straw species. The cover plants cultivated in the cerrado biome region were incorporated an Oxisol Ustox. The straw of each cover plant was incorporated at doses of 0; 10; 20 and 30 Mg ha-1. The soil basal respiration was determined by incubating, after 21 days. The microbial biomass carbon and nitrogen were determined by the method the microwave irradiation. The microbial biomass carbon and nitrogen contents in extracts were determined by the wet combustion method and Kjeldahl-N. The metabolic quotient was calculated as the ratio between soil basal respiration rate and microbial biomass C, and the microbial quotient as the ratio between soil microbial biomass C and total carbon of soil. The soil microbial population measured by the attributes of quality responds to the addition of the of grass and legume straws incorporated to the soil; The treatments that cause the greatest stress to the microbial population, at 21 days, mediated by the metabolic quotient, are guandu-anão at a dose of 10 Mg ha-1; Guandu-anão and Guandu fava-larga at 20 Mg ha-1 and Brachiária at a dose of 30 Mg ha-1; The best result regarding microbial attributes of soil quality evaluated was observed with the incorporation of all doses of the straw of Crotalaria-ocroleuca.

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Starting in the 1950s, agricultural production has been remarkably intensified, resulting in modern management systems where a severe increase in field size led to an elimination of edges and other ecologically valuable structural elements. The resulting habitat loss caused dramatic changes in natural communities. The aim of this work is to test whether there are statistically significant differences in insect abundance over time by using multifunctional margins that are seed mixtures of autochthonous species planted in combined strips, which are the fastest way to provide significant biodiversity benefits within farmed landscapes, enhancing the diversity and abundance of insects, birds, and small mammals, offering resources and reservoirs. This study was carried out in three intensive fruit farms in Spain over a three-year period (2013–2015). Each field was divided into two zones: the margin where a multifunctional margin was planted, and another that remained unchanged in the field. A clear trend to increase RTE species throughout the years in all farms was observed. Moreover, the margin showed a significant difference with respect to the field in the average number of insect species and individuals. The use of margins improves the appearance of RTE species in mean percentages ranging between 12.06 and 25.26% according to the sampling area. Margins also favour the increase in species (148.83–232.84%) and individuals (207.24–586.70%) in agricultural landscapes. These results clearly show that margins are an essential tool to fight insect decline in intensive farming areas.

Copyright of Investigación Agraria is the property of Investigacion Agraria 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 dual-purpose livestock systems in the tropics milk production is reduced during the dry season due to the decrease in the quantity and quality of forage on offer. The impact can be reduced by using forage crops as supplements generated with the use of green fertilizers. The objective of this research was to determinate the nitrogencontribution of legumes in corn forage production. During the years 2013 to 2014, in the Colombian Dry Caribbean three experiments were established with seven levels of nitrogen (N) (0, 25, 50, 75, 100, 150 and 200 kg/ha) and the incorporation of Canavalia brasiliensis (CIAT 17009), Vigna unguiculata (CIAT 4294), Clitoria ternatea (CIAT 21815), Canavalia ensiformis (CIAT 21826) and Lablab purpureus (CIAT 22656) in a random block design. C. ensiformis showed the highest contribution of N (151 kg/ha) and V. unguiculata the lowest (35 kg/ha). The application of 200 kg of N and the incorporation of C. ensiformis and C. brasiliensis did not show a difference in the yield of maize biomass. N use efficiency by corn crop was 31 - 84%, reduced with increased in the dose of N. Levels of NO3 in the soil ranged from 20 to 41 mg/kg at the time of harvest, suggesting that a high proportion of N coming from the legume was not assimilated by the crop. The C:N ratio was 11·63 in legumes and 23·94 in weeds. Organic soil C increased by 22% due to legume green manure, with the highest content (0·70%) in L. purpureus. The legumes C. ensiformis, C. brasiliensis and L. purpureus showed high potential to provide N, C, and to conserve soil moisture. [ABSTRACT FROM AUTHOR]

Highlights • CTS reduces TOC and TN compared to succession/rotation systems in NTS. • Winter grasses in rotation with maize preceding onion crops in NTS increases TOC. • Higher TN is found in areas with more soil cover plant species: T2, T3, T5, T6, T8. • NTS for onion crops high soil aggregate, with predominance of macroaggregates. • T1, T4, T7 reduce soil TOC and macroaggregates, and increase of microaggregates. Abstract Onion is usually cultivated using conventional tillage system (CTS), with excessive soil turning, leaving it with low or no vegetation cover. This favors erosive processes and impacts negatively diverse edaphic attributes. Adopting soil management systems with conservationist bases that use permanent soil coverage and crop rotation can maintain or improve these attributes (for example, soil aggregation and soil organic matter). The objective of this work was to evaluate the total organic carbon (TOC) and total nitrogen (TN) contents, aggregation index, and aggregate mass distribution of a Humic Cambisol cultivated with onions in succession or rotation with other species in no-tillage system (NTS) and CTS. The treatments were: maize/onion (NTS-T1); cover plants (winter)/onion (NTS-T2); maize/winter grasses/onion (NTS-T3); velvet bean/onion (NTS-T4); millet/cover plants (winter)/onion (NTS-T5); velvet bean/rye/onion (NTS-T6); maize/onion (CTS-T7); intercrops cover plants (summer)/onion (NTS-T8). Seven years after the implementation of the experiment, the weighted mean diameter (WMD) of the aggregates, distribution of macroaggregates, mesoaggregates, and microaggregates, and TOC, and TN contents of the soil (0–0.05, 0.05–0.10 and 0.10–0.20 m layers) were evaluated. Periodic soil turning (CTS) in the succession of maize, and onion (T7) reduces TOC and TN contents in the soil surface layer, compared to succession and rotation systems with onion crops in NTS. This negative effect on soil quality is connected to the reduction of aggregate stability, especially the decrease in the amount of macroaggregates. The use of grasses, especially winter grasses in rotation with maize (T3), preceding onion crops in NTS increases TOC content in the soil surface layer. Higher TN accumulation in the surface layer is found in areas with more soil cover plant species in rotation or succession with onion in NTS (T2, T3, T5, T6 and T8). The use of NTS for onion crops generates high soil aggregate stability, with predominance of macroaggregates, regardless of the crop succession or rotation system used. Treatments with no winter soil cover plants (T1, T4 and T7) reduce soil TOC contents and the mass of water-stable macroaggregates and increase the amount of microaggregates in the soil surface layer when compared to the other treatments. [ABSTRACT FROM AUTHOR]

Black pine (Pinus thunbergii) is one of the main afforestation species in the sandy coast and the preferred tree species for landscape green in northern China. Allelopathic activity could be one of the reasons of the sparse vegetation under black pine forests. To explore the allelopathic potential of P. thunbergii, the erects of litter and fresh needles were evaluated against the common cover plants seeds and seedlings, i e. Tateges srecta, Ogchophragmus siolaceus, Ophiopogon japónicas and Trifolium repens. The results showed that P. thunbergi possessed allelopathic potential to the accompanying plants. Increasing concentrations of aqueous extracts of needles and litter affected target plant development in diferent levels. Growth and germination inhibition were directly related to the extract concentrations of needles or litters. Fresh needles played a more important role in the inhibition to target plants than litter because of the less germination rate and biomas in the same concentration. In addition, the adaptability of cover plants to the allelopathic effects of P. thunbergii is obviously diferent. The sensitivities of the four cover plants to the allelopathic effects of P. thunbergii were in order of T. repens > O. japónicas > O. violaceus > T. erecta. Therefore, T. repens is least suitable for concomitant planting with P. thunbergii, and T. erecta is the most suitable, with other two plants in between in landscape configuration. [ABSTRACT FROM AUTHOR]

Abstract Erosion is the main cause of soil degradation, compromising soil productivity and sustainability. As soil organic matter (SOM) is a key indicator of quality, this study aimed to evaluate the effect of different olive tree managements on SOM and its soil fractions in soil (Inceptisol) and erosion sediments. Five treatments were installed: bare soil, olive cultivation in bare soil, olive tree intercropped with jack bean, olive tree intercropped with pearl millet, and olive tree cultivated with spontaneous vegetation; a contiguous area of native vegetation was used as reference. Carbon in soil and sediment were determined by wet oxidation with external heating, while the fractionation of SOM was performed based on granulometry. The Carbon Management Index (CMI) was determined by the proportions of SOM fractions. The results indicated that SOM associated with minerals is the most present in soil and sediment erosion, regardless of the adopted management. Results on CMI showed that the systems olive tree intercropped with pearl millet or with spontaneous vegetation are the most favorable to increase the carbon stock in the soil.

The interest in the use of cover crops associated to conservation management has increased in the last years, since the maintenance of the residues under the soil and their subsequent decomposition are important variables in the nutrient cycling. In this sense, grasses stand out due to the production, persistence and accumulation of phytomass at the soil surface due to the higher C / N ratio. The objective of this study was to evaluate the percentage persistence and the rate of decomposition of straw of Urohcloa ruziziensis in two types of management and in different simulated productivities. The work was conducted at the experimental station of the company Dalcin in Nova Xavantina - MT. The dry mass yields evaluated were 0.9; 1.8; 3.6; 7.3 and 10.9 Mg of dry mass ha-1, in seven collection times (0, 15, 30, 45, 60, 90 and 120 days post-implantation) and in two management systems, conventional planting system (SPC) and notillage system (SPD). In order to evaluate the decomposition, nylon bags were used where the U. ruziziensis residue was placed and maintained under the soil surface (SPD) or buried (SPC). It was verified that the persistence and the decomposition of the U. ruziziensis straw in the SPD presented negative and positive linear adjustment, respectively. In the SPC, the persistence and the decomposition were adjusted to quadratic models, indicating the stabilization of the decomposition of the material in this system. Still, the mean persistence at 120 days in SPD was higher (46%) than in SPC (29%). The higher the mass deposited the higher the percentage of material persistence and the amount of mass decomposed, in both evaluated systems (SPC and SPD). Higher yields of U. ruziziensis in the SPD system offer good persistence of the dry mass on the surface in regions of tropical climate. [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]

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Baixas produtividades e deficiências de nitrogênio coexistem na cultura do milho, sobretudo em sistemas voltados para a agricultura de subsistência. Diante disso, com esta pesquisa buscou-se avaliar os efeitos da utilização de diferentes adubos verdes em sucessão com o milho, sob manejo de cultivo mínimo e convencional, quanto ao aporte de nutrientes ao solo, ao estado nutricional e às características produtivas do milho para a produção de espigas. O experimento foi conduzido em campo, no Norte de Minas Gerais, em esquema de parcelas subdivididas com fatores dispostos no delineamento de blocos ao acaso, com três repetições. Os tratamentos principais foram: crotalária-juncea (Crotalaria juncea), feijão-de-porco (Canavalia ensiformes), nabo forrageiro (Rafhanus sativus), coquetel (crotalária, feijão-de-porco e nabo forrageiro) e plantas daninhas. As subparcelas foram constituídas pelos manejos da adubação verde, no cultivo mínimo ou convencional. Observou-se menor produtividade do milho quando da utilização do tratamento com plantas daninhas. De modo geral, foi identificado maior crescimento das plantas de milho no cultivo mínimo e maior estande no cultivo convencional, sem, contudo, efeito desses manejos na produtividade de espigas. Houve incremento nos teores superficiais de P e K no solo quando no manejo de cultivo mínimo, mas melhor balanço K/Mg nas plantas de milho no cultivo convencional.Low yield and nitrogen deficiency coexist in corn crop, especially under subsistence-oriented systems. Thus, this work aimed to assess the effect of different types of green manure in maize succession, under minimum and conventional tillage, on soil nutrient input, nutritional state, and maize productive features for ear production. The experiment was arranged in a randomized block design, in a split-plot scheme, with three replications, under field conditions in northern Minas Gerais, Brazil. The main plots were constituted by the following types of green manure: sunnhep [Crotalaria juncea), jack beans (Canavalia ensiformes), fodder turnip (Rafhanus sativus), and green manure mixture (sunnhep + jack beans + fodder turnip), besides a treatment with weeds under fallow conditions. The subplots were constituted by conventional and minimum tillage management. Yield was affected by the different types of green manure, with lower values being identified in weed succession. In general, greater plant growth was observed in minimum tillage and higher maize plant density in conventional tillage. However, ear yield was not affected by soil tillage. Higher contents of potassium and phosphorus in 0-10 cm layer depth were observed under minimum tillage, while better K/Mg balance was observed on maize plants under conventional management.

Plants have shown different responses to fertilization with rock phosphate, including responses through alteration of the attributes of rhizospheric soil. The objective of this study was to evaluate soil pH alterations and alterations in the contents of forms of phosphorus in the rhizosphere of soil fertilized with rock phosphate as a result of cultivation of species of plants. An experiment was developed under greenhouse conditions to evaluate alterations in the pH and in the forms of phosphorus in the rhizosphere of an Oxisol fertilized with rock phosphate and cultivated with four species. Treatments consisted of the cultivation of four species of soybean - Glycine max (L.) Merrill, brachiaria grass - Brachiaria brizantha Hochst Stapf, millet - Pennisetum glaucum (L.) R. Brown, and sorghum - Sorghum bicolor (L.) Moench grown in PVC columns filled with soil and divided with a nylon screen (25 µm mesh) to impede root growth in part of the column. After 45 days of cultivation, the soil was divided into the layers of 0-1, 1-2, 2-3, 3-4, 4-5, 5-7, 7-9, and 9-14 mm from the rhizoplane and air dried to determine pH and P contents through Hedley fractionation. In the 1-2 and 2-3 mm layers, soybean cultivation caused an increase in pH when compared to the control treatment (without plants). In the other layers, there were no alterations in pH due to cultivation of plants. The cultivation of millet, brachiaria grass, and sorghum reduced the inorganic P content in the most labile forms only in the 0-1 mm layer from the rhizoplane.

El estudio se realizó en la reserva natural El Ciprés, ubicada en la vereda Bellavista, municipio de El Dovio (Valle del Cauca). La vereda se encuentra en la zona Andina de la cordillera occidental, en el departamento del Valle del Cauca, entre 1700 y 1800 m.s.n.m., con una temperatura promedio de 18 °C. Según la clasificación climática de Holdridge, corresponde a una zona de bosque húmedo Montano Bajo, con una precipitación promedio entre 2500 y 2700 mm/año, una humedad relativa de 90% y una pendiente del suelo de 62%. Las mediciones se hicieron en parcelas de escorrentía de 32 m² cada una y siete tipos de coberturas: guadua (Guadua angustifolia Kunth), bosque secundario, pastura (Brachiaria decumbens), café (Coffea arabica); banco de proteína (Trichanthera gigantea), caña forrajera (Saccharum officinarum) y cultivo limpio conformado por yuca (Manihot esculenta), maíz (Zea mays) y arracacha (Arracacia zanthorrhiza Brancroft). Para la evaluación se midieron las pérdidas de suelo y los nutrientes calcio, magnesio, potasio y fósforo en un periodo de 7 meses. Los resultados mostraron diferencias (P < 0.05) entre las coberturas evaluadas. Las pérdidas más altas de suelo y nutrientes ocurrieron bajo cultivos limpios (2.61 t/ha) y las más bajas en guadua (0.08 t/ha). Estos resultados sugieren ventajas de los bosques de guadua en esta zona de Colombia, ya que además de contribuir a la conservación de los suelos y al mantenimiento de la fertilidad, es una alternativa económica complementaria para los productores rurales a partir de su manejo y aprovechamiento.Soil and nutrient (calcium, magnesium, potassium, phosphorus) losses were measured over a 7-month period in the El Ciprés Natural Reserve, located in the Bellavista rural community, municipality of El Dovio, in the western cordillera of the Andes of the department of Valle del Cauca, Colombia. At 1700-1800 meters above sea level, the area presents an average temperature of 18 °C, an average annual precipitation of 2500-2700 mm, 90% relative humidity, and a 62% slope. According to the Holdridge climate classification system, it corresponds to a lower montane rain forest. Measurements were taken in runoff plots, each 32 m², with seven types of vegetation cover: giant bamboo (Guadua angustifolia Kunth); secondary forest; pastures (Brachiaria decumbens); coffee (Coffea arabica); protein bank (Trichanthera gigantea); forage cane (Saccharum officinarum), and a clean crop formed by cassava (Manihot esculenta), maize (Zea mays), and arracacha (Arracacia zanthorrhiza Brancroft). Results showed differences (P < 0.05) between the different types of vegetation cover. The higher loss of soil and nutrients occurred in clean crops (2.61 t/ha) and the lowest in giant bamboo (0.08 t/ha). These results suggest the advantages of conserving giant bamboo forests in this part of Colombia because not only do they contribute to soil conservation and maintenance of fertility, but they are a complementary economic alternative for rural producers.

Espécies florestais exóticas têm sido utilizadas para a recuperação de solos degradados, auxiliando no controle da erosão hídrica e eólica. No sudoeste do Rio Grande do Sul, foram testados o Pinus elliotii Engelm. e o Eucalyptus tereticornis Sm., com o objetivo de avaliar o crescimento destas espécies e testar sua capacidade na contenção do fenômeno da arenização. Os tratamentos consistiram do plantio das duas espécies sobre o solo degradado por arenização (SD), sobre o campo nativo (C), sobre o campo nativo associado a plantas de cobertura (C + PC) e sobre o solo degradado com plantas de cobertura (SD + PC). Como plantas de cobertura, foram testadas a aveia preta (Avena strigosa Schieb.) e um tremoço nativo do ecossistema dos campos sulinos, o Lupinus albescens H. et Arn.. Determinaram-se o percentual de sobrevivência inicial, a altura, o diâmetro à altura do colo (DAC) e o fator de produtividade (FP) das espécies florestais, aos 30 dias, seis meses e 12 meses após plantio. O experimento foi conduzido em delineamento inteiramente casualizado, e os resultados submetidos ao teste de Duncan, em um nível de 5% de probabilidade de erro. Em relação à sobrevivência inicial, apenas o pínus apresentou diferenças estatísticas, com menor percentual no tratamento C+PC. Os resultados demonstraram que o eucalipto beneficiou-se do consórcio com plantas de cobertura, enquanto o pínus apresentou maior sensibilidade à competição interespecífica.Exotic forest species have been used for soil reclamation, as well as helping in the control of water and wind erosion. In the southwest of Rio Grande do Sul state, Brazil, the Pinus elliotii Engelm. and the Eucalyptus tereticornis Sm., were tested with the objective of evaluating the growth of these species and testing its capacity for reducing the arenization process. The treatments consisted of planting the two species on the degraded soil by arenization (DS), on the native grassfield (C), on the native grassfield associated with cover crops (C + PC) and on the degraded soil associated with cover crops (DS + PC). As cover crops were tested the black oat (Avena strigosa Schieb.) and a Lupinus native from the southern grassfields ecosystem, the Lupinus albescens H. et Arn.. The plants survival rate, height, basal diameter and the productivity factor of the forest species were obtained in the thirty days, six months and twelve months after planting. The experiment was conduced in completely randomized design, and results submited to Duncan test, in level of 5% error probability. In relation to initial survival, only pine presented significative differences, with lesser percentual in the treatment C+PC. Results showed that Eucalyptus benefited from the consortium with cover crops, while pine presented greater sensibility to interespecific competition.

O objetivo foi avaliar a interação entre palhadas e doses de nitrogênio, na nutrição e rendimento de grãos do feijoeiro, sob plantio direto. O delineamento foi de blocos casualizados, com quatro repetições, em esquema de parcelas subdivididas. As palhadas influenciaram o teor de Fe e as doses de N os teores de N, Ca, Mg e Mn. Houve interação entre palhadas e doses para os teores de P, K e S. O maior teor foliar de Fe ocorreu sob palhada de guandu-anão e de N na dose de 62 kg ha-1 do nutriente. Para os teores de Ca, Mg e Mn, houve respostas lineares, sendo negativa para o Ca e positivas para os dois últimos. Para o P, houve pequena redução, com posterior acréscimo nas palhadas de milheto e milheto+feijão-de-porco. Os teores de K aumentaram até próximo de 50 kg ha-1 de N, com posterior redução sob as palhadas de milheto consorciado com as leguminosas.Nas palhadas de milheto e guandu-anão, houve redução a partir de pequenas doses de N. Os teores de S aumentaram de forma quadrática nas palhadas com milheto. O maior rendimento foi obtido sob milheto+feijão-de-porco na maior dose de N. The object was to evaluate the dry bean nutrient contents and grain yield in no-till. The study was carried out in a randomized block design, and four replications, with a split-plot arrangement. The dry bean macro and micronutrients contents and grain yield were determined. The straws significantly influenced Fe content, while nitrogen fertilization levels influenced N, Ca, Mg and Mn contents. There were significant interactions between straws and the rate of N for P, K and S contents. The greatest dry bean Fe foliar content was observed under dwarfguandu straw. N contents increased until the rate of 62 kg ha-1 N, and experienced reduction after that level. The N rates provided linear effects in Ca, Mg and Mn contents, being negative for Ca and positive for the others. P contents had little reduction with increases in millet and millet+jack-bean straws. K contents increased until rates near 50 kg ha-1, with reduction after that level under all the straws with millet presence. Under milletand dwarf-guandu straws, the reduction occurred starting at small N rates. S contents increased quadratically, only under straws where millet was present. The best grain yield was obtained under millet+jack bean in the largest N rate.

Objetivou-se com este trabalho avaliar o efeito de diferentes coberturas de plantas sobre a qualidade fisiológica de sementes de feijão em plantio direto no município de Diamantina - MG. O experimento foi instalado no Campus II da UFVJM, num Neossolo Quartzarênico Órtico típico, no delineamento em blocos casualizados, com dez tratamentos e quatro repetições. Os tratamentos constituíram-se de palhada dessecada e roçada de 1) Brachiaria decumbens cv. Basilisk, 2) Brachiaria brizantha cv. Marandu, 3) Panicum maximum cv. Tanzânia, 4) Panicum maximum cv. Mombaça, 5) Mucuna aterrina (mucuna preta), 6) Calopogonio muconoides cv. Calopogonio, 7) Dolichos lab lab (lab lab), 8) Cajanus cajan (guandu), 9) Cobertura natural e 10) Plantio convencional onde se efetuou o plantio de feijão cultivar Talismã. A qualidade fisiológica das sementes foi avaliada pelos testes de germinação (primeira contagem e contagem final); condutividade elétrica dos solutos; peso de 100 sementes; comprimento e peso das plântulas; índice de velocidade de germinação e teor de água das sementes de feijão. As gramíneas Panicum. maximum cv. Mombaça, Brachiaria brizantha cv. Marandu, B. decumbens cv. Basilisk e P. maximum cv. Tanzânia produziram matéria seca em quantidade e uniformidade para maior conservação de água e proteção do solo para viabilizar o sistema plantio direto. A qualidade das sementes não foi afetada pelos manejos de solo utilizados e sim pelas condições climáticas na maturação.The objective this work was evaluate the effect of different coverings plants on the physiological quality seeds of bean in no-tillage system in Diamantina - MG. The experiment was installed in the Campus II of UFVJM, in a Neossolo Quartzarênico Órtico típico, in blocks randomized design, with ten treatments and four replicates. The treatments were constituted of control chemical and rubbed straw of 1) Brachiaria decumbens cv. Basilisk, 2) Brachiaria brizantha cv. Marandu, 3) Panicum maximum cv. Tanzania, 4) Panicum maximum cv. Mombaça, 5) Mucuna aterrina (black mucuna), 6) Calopogonio muconoides cv. Calopogonio, 7) Dolichos lab lab (lab lab), 8) Cajanus cajan (guandu), 9) Natural covering and 10) Conventional plantation where the bean plantation was made to cultivate Talisman. The physiological quality of the seeds was evaluated by the germination tests (first and final count); electric conductivity of the solute; weigh of 100 seeds; length and weight of the plants; index of germination speed and text of water of the bean seeds. The grass Panicum. maximum cv. Mombaça, Brachiaria brizantha cv. Marandu, B. decumbens cv. Basilisk and P. maximum cv. Tanzania produced dry matter in amount and uniformity for larger conservation of water and protection of the soil to make possible the no-tillage system. The quality of the seeds was not affected by the used soil handlings but had the influence of the climatic conditions in the maturation.

Objetivou-se avaliar a influência de sistemas de manejo no rendimento de grãos de feijão em um Latossolo Vermelho de cerrado. A pesquisa iniciou-se em 1997 e a avaliação do rendimento de grãos foi realizada no inverno de 2002. Utilizou-se o delineamento experimental de blocos ao acaso no esquema em faixas com parcelas subsubdivididas. Os tratamentos foram constituídos nas faixas pela combinação de 5 plantasde cobertura (Mucuna aterrima, Pennisetum americanum, Crotalaria juncea, Cajanus cajan e pousio); no outro sentido, as faixas foram subdivididas e constituídas pelo sistema de semeadura direta e convencional (preparo do solo com grade aradora e grade niveladora), as quais, por sua vez, foram subsubdivididas com as culturas de verão milho, soja e algodão. Concluiu-se que as plantas de cobertura, após cinco anos, não influenciaram o rendimento de grãos; a massa de 100 grãos de feijão foi maior na semeadura convencional, porém, orendimento não diferiu entre os preparos; na semeadura convencional, a sucessão com algodão, nos dois primeiros anos agrícolas, proporcionou grãos de feijão mais pesados e maior rendimento; na semeadura direta, a sucessão que incluía algodão ou soja nos doisprimeiros anos agrícolas proporcionou maiores rendimentos ao feijoeiro.This study aimed to evaluate the influence of management on common bean in Oxisol. The research began in 1997 and the yield evaluation was carried out in the winter of 2002. The experimental design was randomized blocks with split split-plot design. The treatments were constituted by the combination of five cover plants, two soil tillages and three crop successions. It was concluded that cover plants, after five years, did not influence the common bean; the 100-grain weight of bean was higher in conventional tillage, but theyield did not show any difference between the tillages; in conventional tillage, cotton crop sucession in the first two years provided larger common bean weigth and yield; in the notillage,the successions with cotton and soybean in the first two years resulted in larger common bean yeld.