Urochloa Ruziziensis Research Articles

INFLUENCE OF DROPLET SIZE ON SPRAY DEPOSITION AND WEED CONTROL USING GLYPHOSATE

Droplet size is one of the most important factors that affect spray deposition and weed control through the use of herbicides. The aim of this study was to evaluate the influence of the droplet size on the spray deposition and control of Euphorbia heterophylla and Urochloa ruziziensis by using glyphosate. The treatments included spraying glyphosate with fine, medium, coarse, very coarse, and ultra-coarse droplet sizes to determine the deposition, uniformity of distribution, visual control, and dry weight reduction (DWR). The treatments were compared with the values of the dose required to achieve 50% DWR or 50% visual control (C50) at 7, 14, 21, and 28 days after herbicide application. Fine and medium droplet sizes afforded high deposition values and low distribution uniformities in E. heterophylla . Fine and medium droplet sizes yielded the lowest C50 on visual control and DWR in E. heterophylla, respectively. The droplet size did not affect the spray deposition on U. ruziziensis plants; however, the larger droplets had less uniformity of distribution. In U. ruziziensis plants, spraying glyphosate with coarse and medium droplet sizes yielded the lowest values of C50 to visual control and DWR, respectively.

Microbiological Attributes and Performance of the Bacterial Community in Brazilian Cerrado Soil with Different Cover Crops

Soil microbiological indicators are essential tools to understand how the management with cover crops interferes in the activity and the soil microbial community. Thus, the objective of the study was to evaluate microbiological attributes and performance of the bacterial community in the soil of the Brazilian Cerrado with different cover crops. The experiment was performed in a randomized block design, evaluating seven cover crops, Sorghum bicolor, Crotalaria ochroleuca, Pennisetum americanum, Panicum miliaceum, Raphanus sativus, Urochloa brizantha, Urochloa ruziziensis, and a fallow area. Cover aerial biomass dry weight (CB), microbial biomass carbon (MBC), basal soil respiration (BR), metabolic quotient (qCO2), and abundance and structure of bacterial community based on the rrs 16S rRNA gene were evaluated. In the soil cultivated with S. bicolor there was the highest CB and MBC at the same time as there was less microbial activity (lower BR and qCO2). The structure of the bacterial community was more differentiated in soils cultivated with S. bicolor, P. americanum, and C. ochroleuca. The MBC was more associated with cover crops of the Urochloa genus, while BR was positively correlated with S. bicolor. Bacterial abundance was positively correlated with P. miliaceum.

Early nitrogen supply as an alternative management for a cover crop-maize sequence under a no-till system

Optimizing agronomic efficiency (AE) of nitrogen (N) fertilizer use by crops and enhancing crop yields are challenges for tropical no-tillage systems since maintaining crop residues on the soil surface alters the nutrient supply to the system. Cover crops receiving N fertilizer can provide superior biomass, N cycling to the soil and plant residue mineralization. The aims of this study were to (i) investigate N application on forage cover crops or cover crop residues as a substitute for N sidedressing (conventional method) for maize and (ii) investigate the supply of mineral N in the soil and the rates of biomass decomposition and N release. The treatments comprised two species, i.e., palisade grass [Urochloa brizantha (Hochst. Ex A. Rich.) R.D. Webster] and ruzigrass [Urochloa ruziziensis (R. Germ. and C.M. Evrard) Crins], and four N applications: (i) control (no N application), (ii) on live cover crops 35 days before maize seeding (35 DBS), (iii) on cover crop residues 1 DBS, and (iv) conventional method (N sidedressing of maize). The maximum rates of biomass decomposition and N release were in palisade grass. The biomass of palisade grass and ruzigrass were 81 and 47% higher in N application at 35 DBS compared with control in ruzigrass (7 Mg ha−1), and N release followed the pattern observed of biomass in palisade and ruzigrass receiving N 35 DBS (249 and 189 kg N ha−1). Mineral N in the soil increased with N application regardless of cover crop species. Maize grain yields and AE were not affected when N was applied on palisade grass 35 DBS or 1 DBS (average 13 Mg ha−1 and 54 kg N kg−1 maize grain yield) compared to conventional method. However, N applied on ruzigrass 35 DBS decreased maize grain yields. Overall, N fertilizer can be applied on palisade grass 35 DBS or its residues 1 DBS as a substitute for conventional sidedressing application for maize.

Soil chemical attributes and nutritional status of soybean and maize intercropped with Urochloa under nitrogen rates

AbstractMaize (Zea mays L.) intercropping with forage plants has been adopted with the main goal of promoting benefits on soil physical properties. However, a better understanding of soil chemical attributes and crops nutrition under this system is necessary. The objective was to verify whether intercropping maize with Urochloa ruziziensis (Germ. & Evrard) Crins, a tropical forage grass originating in Africa, associated with N rates, could provide modifications on soil chemical attributes and nutritional status of maize and soybean [Glycine max (L.) Merr.] grown in succession. The experiment was carried out for three agricultural years at field conditions in a Rhodic Hapludox soil under no‐till system in the state of Paraná, Brazil. Fall/winter (March–August) maize cropping systems, sole or intercropped with U. ruziziensis, were associated with four nitrogen (N) rates (0, 40, 80, and 120 kg ha–1 N) applied as ammonium nitrate (30% N). The soil chemical attributes were not influenced by the factors studied. The N rates linearly increased phosphorus (P), sulfur (S), and copper (Cu) concentrations in maize leaves by 29, 30, and 49%, respectively, whereas for soybeans, only the concentration of manganese was raised by 15%. Maize leaf calcium was linearly reduced with N rates only when sole cropped, up to 15%. The cropping systems did not influence nutrient concentrations in soybean leaves; however, maize leaf concentrations of P within 80 and 120 kg ha–1 of N, as well as potassium, S, and Cu at all N rates, were reduced in 9, 6.5, 6.5, and 8%, respectively.

Morphogenic responses and biochemical alterations induced by the cover crop Urochloa ruziziensis and its component protodioscin in weed species

Urochloa ruziziensis, a cover plant used in no-till systems, can suppress weeds in the field through their chemical compounds, but the mode of action of these compounds is still unknown. The present study aimed to investigate the effects of a saponin-rich butanolic extract from U. ruziziensis straw (BfUr) and one of its components, protodioscin on an eudicot Ipomoea grandifolia and a monocot Digitaria insularis weed. The anatomy and the morphology of the root systems and several parameters related to energy metabolism and antioxidant defense systems were examined. The IC50 values for the root growth inhibition by BfUr were 108 μg mL−1 in D. insularis and 230 μg mL−1 in I. grandifolia. The corresponding values for protodioscin were 34 μg mL−1 and 54 μg mL−1. I. grandifolia exhibited higher ROS-induced peroxidative damage in its roots compared with D. insularis. In the roots of both weeds, the BfUr and protodioscin induced a reduction in the meristematic and elongation zones with a precocious appearance of lateral roots, particularly in I. grandifolia. The roots also exhibited features of advanced cell differentiation in the vascular cylinder. These alterations were similar to stress-induced morphogenic responses (SIMRs), which are plant adaptive strategies to survive in the presence of toxicants. At concentrations above their IC50 values, the BfUr or protodioscin strongly inhibited the development of both weeds. Such findings demonstrated that U. ruziziensis mulches may contribute to the use of natural and renewable weed control tools.

WEEDS IN SOYBEAN CULTIVATION WITH DIFFERENT PREDECESSOR COVER CROPS

The competition between soybean and weeds affects crop development due to reduced resources such as water, light, and nutrients, leading to yield losses. Thus, the study aimed to evaluate quantitatively and qualitatively, through phytosociology and seed bank, the weed presence in a soybean cultivation area with different predecessor cover crops. The experiment was installed under no-till system conditions using a randomized block design with nine treatments and three replications. The treatments were composed of the following cover crops, sorghum (Sorghum bicolor), crotalaria (Crotalaria ochroleuca), millet (Pennisetum americanum), Urochloa ruziziensis, U. brizantha cv. Piatã, fodder radish (Raphanus sativus L.), U. brizantha cv. Xaraés, millet + fodder radish, and fallow. The soybean crop was established on the cover crops in the 2019/20 harvest. Soybean characteristics, the seed bank, and weed phytosociology were evaluated. The highest soybean yield was obtained with U. ruziziensis as predecessor cover crop, reaching 4530 kg ha-1. It was concluded that the following cover crops, sorghum, crotalaria, and millet, were the ones that most suppressed the soil weed seed bank. Contrarily, the fallow provided the greatest viable seed number. The weed species Eleusine indica, Digitaria insularis, and Cenchrus echinatus had higher phytosociological values in all treatments.

Shade effects on the hybrid Mavuno brachiariagrass (Urochloa spp.) as potential grass in agroforestry systems

The goal of this study was to evaluate the morphogenetic, physiology, and forage mass characteristics of Mavuno brachiariagrass (Urochloa brizantha × Urochloa ruziziensis) under shading. The experiment was analyzed as split-plot. Whole plots were two growing seasons (spring/summer and fall/winter) and the subplots were shade levels (0, 30, 45, and 73%). There is a linear positive effect of shade on leaf elongation rate, leaf blade lengths, canopy height, chlorophyll indices, leaf percentage, and leaf to stem ratio. Shade linearly decreased stem and inflorescence percentages and tillers number. There was a quadratic effect of shade on growing cycle length, forage mass, and photosynthesis. Regarding to seasons, spring/summer presented higher rates of leaf appearance, leaf elongation, and stem elongation compared to fall/winter. In conclusion, Mavuno brachiariagrass harvested at 95% LI presents great adaptation to shading of 30%, without impairing the forage mass although increasing leaf size, chlorophyll indices, and canopy height.

Nitrogen fertilization on soybean crop over straw of forage sorghum intercropped with Urochloa ruziziensis

The experiment was carried out to evaluate the influence of N on the agronomic characteristics of soybean crop under no-tillage system over forage sorghum intercropped with Urochloa ruziziensis and on straw degradation. Four treatments (nitrogen doses) were used: 0; 20; 40 and 60 kg of N ha-1. N were applied at V3-V4 stage, using ammonium nitrate as the N source, containing 30% N. The experimental design was a randomized block design with four replications. The evaluation of dry matter quantity of forage sorghum and U. ruziziensis straw was carried out before the sowing of forage sorghum and U. ruziziensis and after soybean harvest. The soybean crop parameters evaluated were, as follows: first pod insertion height and plant height, final stand ha-1 and grain yield ha-1. Evaluations were performed at the soybean crop harvest. Nitrogen fertilization did not influence the straw decomposition of U. ruziziensis and forage sorghum nor the first pod insertion height, plant height and final stand ha-1 of soybean crop. Nevertheless, fertilization showed a quadratic behavior in the 2015/2016 crop in relation to grain yield, with a reduction in yield at doses greater than 21 kg of N ha-1, and a linear increase in the 2016/2017 crop. Key words: Ammonium nitrate, Glycine max L., no-tillage.

Increase of soybean yield through agricultural practices in Central Brazil

The soybean-second-crop corn succession is the main grain production system in the Midwest region of Brazil; however, the greatest obstacle of this system is the low soil cover rates. Thus, this study aimed to evaluate the influence of inoculation and co-inoculation of Bradyrhizobium japonicum and Azospirillum brasilense on soybean yield in succession to autumn-winter crops. The experiment was carried out in Dourados, Mato Grosso do Sul during the 2018-2019 and 2019-2020 harvests. The experimental design was randomized blocks with treatments in a 4×3 factorial scheme, with four replications. The four autumn-winter crops constituted the first factor: single corn, corn-brachiaria intercropping, Urochloa ruziziensis established since 2013, and U. ruziziensis established since 2016. The second factor was based on inoculation treatments (without inoculation, inoculation of B. japonicum, and co-inoculation of B. japonicum with A. brasilense). The Urochloa ruziziensis cultivated in autumn-winter contributes to increasing the soybean grain yield in succession. Co-inoculation of Bradyrhizobium japonicum with Azospirillum brasilense complements biological nitrogen fixation, contributing to soy development.

Differential responses of three Urochloa species to low phosphorus availability

AbstractUrochloa (syn. Brachiaria spp.) is the most cultivated forage species in the tropics and is being introduced to agroecosystems as it can provide multiple services, such as nutrient cycling. In this regard, phosphorus (P) cycling has received particular attention for its little availability in soils and the fact that Urochloa has mechanisms to cope with its low availability. However, there are interspecific differences regarding adaptation to low fertility and P requirements among Urochloa species. This study aimed to evaluate the responses of three Urochloa species—Urochloa brizantha, Urochloa decumbens and Urochloa ruziziensis—to low P availability, as well as their mechanisms to grow on these conditions. We conducted a hydroponic experiment with three levels of P availability—10% (6.2 mg P dm−3), 25% (15.5 mg P dm−3) and 100% (62 mg P dm−3)—and evaluated plant biomass production, P tissue concentration, root acid phosphatase activity, root exudation and P transporter expression on roots. We identified several metabolites in root exudates including amino acids, non‐protein amino acids, polyamides, organic acids and phenolic acids. Although all metabolites were found in all the species, metabolite exudation varied among species and P level. Overall, U. brizantha and U. ruziziensis plants exudated more metabolites when growing under P limitation (10 and 25% P), which can be a response to low P availability and stress. We identified three P transporters in roots from the PHT1 family—UPHT1;1a, UPHT1;1b and UPHT1;1c. We did not find an explicit expression pattern for UPHT1;1a, but the expression of UPHT1;1b and UPHT1;1c increased at low P availability. U. ruziziensis accumulated more biomass than the other species at all levels of P availability, possibly because of the greater expression of these P transporters. Urochloa species differ regarding nutrient availability requirements, including P, which may explain the P transporters expression and metabolite exudation results. Thus, to cope with low P in the soil, the species developed different metabolic strategies to improve the uptake of this nutrient.

Crop succession and split-application of nitrogen effects on common bean yield in short no-tillage system

AbstractEvaluating the effects of crop successions in no-tillage system (NTS) is essential for the correct recommendation of agronomic practices, such as top-dressing nitrogen fertilization. The aim was to evaluate the effect of the crop succession and the splitting of top-dressing N fertilization on the agronomic performance and economic viability of common bean crop. The experiment was conducted in southeastern Brazil for two agricultural seasons in an area under NTS, using a split-plot in randomized complete block design. The plots represented three cropping successions (maize in sole crop, maize intercropped with Urochloa ruziziensis and U. ruziziensis in sole crop) and the subplots composed of ten combinations of splitting of top-dressing N, at the stages V3, V4 and R5 of the common bean crop. In relation to the single application of the N dose of 90 kg ha−1, the common bean had higher response as a function of the N splitting schemes adopted, regardless of the previous cropping succession. The cropping successions evaluated did not interfere with the seed yield of common bean as subsequent crop, even at the beginning of the establishment of NTS. To obtain higher seed yield and economic viability, the N dose of 90 kg ha−1 indicated for the crop must be split and applied among the phenological stages V3, V4 and R5.

Nanostructures and properties of an Oxisol under no-tillage and mechanical chiseling

Soil compaction in no-tillage systems (NTS) affects the sustainability of this management. To overcome the problem, mechanical chiseling and maintenance of the vegetation cover suggested were as management practices in order toreestablish ideal cultivation conditions. The soil studied was occupied for 20 years with annual crops in conventional tillage system (plowing and leveling harrow). After, the NTS was implemented for 15 years old. In 2012, management were implemented to study the effects on soil quality, with mechanical chiseling, cover crops, rice and bean. Thepurpose of this study was to evaluate the effect of soil chiseling and the use of cover crops on the maintenance of NTS sustainability after a crop succession of rice and common bean on a clayed Orthic Ferralsol. After four years we evaluation were then carried out to analyze the effects of the system on the soil quality physical and chemical attributes. We studied five cover plants (Crotalaria juncea; Cajanus cajan; Pennisetum glaucum; Urochloa ruziziensis and Fallow) all in NTS with and without chiseling. In addition, we studied a natural Savannah fragment too. Chiseling with cultivation of Crotalaria juncea as vegetation cover improved the physical properties compared with the initial conditions. However, cover crops grown on unchiseled soil resulted in an increase in the chemical properties P, K, and Mg concentrations, pH, and soil organic matter. The soil nanostructures morphological characteristics is a promising indicator it quality, complementary to the chemical indicators, for being sensitive enough for the short-term detection of changes soil properties.

Cultivation of ruziziensis grass (Urochloa ruziziensis) using swine liquid manure fertilization

The objective of this study was to evaluate the use of liquid swine manure (LSM) as fertilization in the implantation of Urochloa ruziziensis. The experimental design was randomized blocks with five treatments and four replications, with the treatments being four doses of LSM (0; 100; 200 and 300 m3 ha-1) and one dose of mineral fertilization. Seven cuts were carried out uniformly, after which plant height (PH), total dry mass yield (TDMY), crude protein content (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF), macromineral extraction (N, P, K, Ca, Mg and S) and microminerals (Fe, Zn, Mn and Cu) of plants were evaluated every 30 days. Mineral fertilization provided higher PH, CP content and extraction of N and S, but lower NDF content. For ADF variable, there was no difference between treatments. The results of dry mass yield (DMY) and extractions of P, K, Ca and Mn showed that the effect of 300 m3 ha-1 LSM was statistically equal to mineral fertilization. For extractions of Mg, Fe, Zn and Cu doses of 200 and 300 m3 ha-1 did not differ statistically from mineral fertilization. Among the doses of LSM, there was increasing linear effect, with increases in the variables DMY (30.89%), PH (14.94%), CP (17%), N (53.01%), P (40.79%), K (27.84%), Ca (35.17%), Mg (29.6%), S (47.13%), Fe (31.2%), Zn (31.6%) and Mn (23.04%). For Cu extraction, there was a quadratic effect with the highest extraction in the dose of 26.36 m3, obtaining an increase of 19.94% in relation to treatment without application. It is important to study different LSM dosages to avoid risk of heavy metal toxicity. The LSM is an alternative in place of mineral fertilization for Urochloa ruziziensis grass.

Interseeding of ruzigrass into soybean: Strategies to improve forage cultivation in no-till systems

No-till (NT) farming is a major soil conservation strategy. In the Brazilian Cerrado, soybean is the main grain crop, and strategies that improve the cultivation of cover crops in the off-season in succession to soybean could facilitate NT for large cultivated areas. In the municipality of Nova Xavantina, MT, Brazil, three experiments were carried out in a randomized block design with four replications. This work aimed to evaluate the establishment of Urochloa ruziziensis (ruzigrass) in succession to soybean as a function of ruzigrass seed treatment, sowing density and phenological stage, and soybean cultivar allelopathic potential. In the first experiment, treatment of ruzigrass seeds with six doses (0, 150, 300, 450, 600 and 750 mL of commercial product 100 kg−1 of seeds) of fipronil + thiophanate-methyl + pyraclostrobin was evaluated. In the second experiment, two ruzigrass interseeding periods (soybean phenological stages R5.5 and R7) and five ruzigrass seed densities (4.3, 6.4, 8.6, 10.7 and 12.9 kg ha−1 VPS) were tested. In the third experiment, the interference of soybean cultivars in the establishment of ruzigrass and the potential allelopathic effect of the cultivars on forage germination were evaluated, six soybean cultivars RR (Roundup Ready®) were used: P98Y70; TMG 115; TMG 132; M 8527; P98Y11; TMG 123. Our results showed that seed treatment facilitated forage establishment in the interseeding system, and the use of high sowing rates at phenological stage R5.5 of soybean promoted greater ruzigrass plant development. The effects of the soybean cultivars on ruzigrass germination varied, suggesting allelopathic effects of the deposition of petioles and soybean leaves on ruzigrass seeds. Thus, an appropriate interseeding strategy can improve forage production in the off-season and favor NT through correct management of forage establishment in succession to soybean.

Recovering Soils Affected by Iron Mining Tailing Using Herbaceous Species with Mycorrhizal Inoculation

The objective of this research was to evaluate a soil recovery strategy in soils that were affected by iron mining tailing using herbaceous species inoculated with Acaulospora morrowiae (arbuscular mycorrhizal fungus (AMF)). Tailings were collected on the banks of the Gualaxo do Norte river, one of the places impacted by the Fundao Dam rupture, where tailing layers that were more than one meter were deposited. The experiment was carried out in a greenhouse, using 6 kg pots of non-sterile reject, in a randomized block design in a 4 × 2 factorial scheme, with four cropping systems (Urochloa ruziziensis single crop–RS; and intercropping cultivation: U. ruziziensis with Crotalaria spectabilis–R + C; U. ruziziensis with Guizotia abyssinica–R + G and U. ruziziensis with C. spectabilis and G. abyssinica–R + C + G), with two AMF inoculation conditions (with 200 A. morrowiae spores per pot, and no inoculation), with three replications and 100 days duration. The R + C and R + C + G systems presented the highest shoot dry matter (SDM) yields. Regarding root dry matter production (RDM), a variation of 9.2 g of pot−1 roots was observed between the R + C and R + G systems. Mycorrhizal colonization (MC) was higher in the cultivation system with the three herbaceous species, being the R + C + G system 52% higher than RS system. Spore density did not vary among treatments. Microbial carbon biomass was higher in the RS and R + G treatments when not inoculated. Basal respiration was also higher when not inoculated. Overall, the R + C + G system was more efficient than other systems in the accumulation of elements. The cultivation system with three herbaceous plants proved to be efficient in establishing itself initially in the iron mining tailings, being a viable alternative for the rehabilitation process.

Soil organic C affected by dry‐season management of no‐till soybean crop rotations in the tropics

Cover crop species selection for soybean (Glycine max) production under no-tillage (NT) management may affect soil organic C sequestration by altering the quantity and quality of C inputs, thereby affecting cropping system sustainability. If so, the underlying mechanisms for such regulation are still unclear. We assessed changes in soil C and N fractions at 0-0.1 m depth and soil C stock at 0-0.6 m depth during the last three years of dry-season cover cropping in a soybean production system managed with NT for 9 years on a Rhodic Hapludox in Sao Paulo, Brazil. Dry-season management treatments were repeated yearly in a split-plot scheme. Main plots during the fall-winter were (1) ruzigrass (Urochloa ruziziensis), (2) grain sorghum (Sorghum bicolor), and (3) the intercropping of ruzigrass and sorghum. Subplots during spring prior to planting soybean were (a) pearl millet (Pennisetum glaucum), (b) sunn hemp (Crotalaria juncea), and (c) forage sorghum (Sorghum bicolor). Soil C and N fractions were affected according to crop residue characteristics of the rotations. Higher soil C stocks in 2012 and 2015 (7 % an average) were observed at 0.2–0.4 m depth by ruzigrass compared to sorghum. High crop residue input with ruzigrass in the fall-winter sequestered 0.61 Mg C ha− 1 yr− 1 at 0-0.1 m soil depth compared with lower C sequestration using grain sorghum (0.29 Mg C ha− 1 yr− 1). The quantity and quality of crop residues impact its retention on soil surface controlling the dynamics of soil C and N fractions and can be considered relevant for soil C sequestration. These aspects could contribute to the mitigation of atmospheric CO2 in crop production systems.

Maize yield under Urochloa ruziziensis intercropping and previous crop nitrogen fertilization

AbstractMaize intercropping with forage crops and N under no‐tillage management have led to discrepant results regarding the impact on crop yield. Therefore, understanding various production systems is necessary to assist producers in decision making. The aim of this experiment was to evaluate whether maize (Zea mays L.) intercropping with Urochloa ruziziensis (R. Germ. and C.M. Evrard) Crins promotes differences in the agronomic performance of maize and if split top‐dressing N fertilization in the previous crop (common bean [Phaseolus vulgaris L.]) promotes increase in maize agronomic performance. The experiment was conducted during two agricultural years in southeastern Brazil, with treatments arranged as a split‐plot fitted in a randomized block design, with four replications. Main plot was cropping systems (two systems ‐ maize sole and maize intercropped with U. ruziziensis) while subplots comprised 10 combinations of split top‐dressed N applications, totaling 90 kg ha−1, applied to the previously cultivated common bean crop. Regardless of the agricultural year, intercropping with U. ruziziensis sown simultaneously with maize reduced maize yield by 12% on average. Intercropping maize and U. ruziziensis increased soil coverage from an average of 64–100% over maize as an only crop. The agronomic performance of maize grown in sole crop or intercropped with U. ruziziensis was not influenced by the effect of top‐dressing N fertilization applied in common bean under no‐tillage as previous crop. Intercropping maize with U. ruziziensis is a viable option for producers seeking improved soil coverage or grazing opportunities, however, caution is needed since maize yields may be reduced.

Cover crops, lime and gypsum influence on soil physical attributes

Cover crops promote nutrient cycling, and lime and gypsum can alter the soil physical attributes. This study aimed to evaluate the effect of lime and gypsum rates applied to a no-tillage system with addition of residues of three cover crops on the soil physical attributes. This experiment was carried out in chapadão do sul-ms. The treatments were comprised of three cover crops (Urochloa ruziziensis, fallow, and Pennisetum glaucum), with gypsum (0, 2.3 and 4.6 Mg ha-1) and lime applied at a dose of 0, 2, 4, 6 Mg ha-1).The attributes evaluated were: soil density, macroporosity, microporosity, total porosity and penetration resistance. The soil of the experiment was classified an Oxisol. Cover crops and lime and gypsum improved macroporosity, microporosity and total porosity at all depths, 0-0.2 m. Millet presented lower values for penetration resistance with the lime application and without gypsum application. No residual effect on soil density was detected for lime and gypsum application or cover crops in the 0.1-0.2 m layer. Brazilian Cerrado producers will have a well-defined management system to follow aiming at improving the soil physical attributes.

COVER CROPS IN THE OFF-SEASON IN THE WEED MANAGEMENT AT NOTILLAGE AREA

ABSTRACT Cover crops can provide suppression of weeds and together with chemical control make the proper management of weeds in agricultural areas. The objective of this study was to evaluate the effect of cover crop cultivation during the off-season on weed development in a no-tillage area. The experimental design was in randomized blocks scheme with six treatments and four replications. The treatments were: fallow (control), millet (Pennisetum glaucum) + crotalaria (Crotalaria spectabilis + C. juncea + C. ochroleuca), millet + pigeon pea (Cajanus cajans), millet + Urochloa ruziziensis, millet + Urochloa ruziziensis + pigeon pea and millet + buckwheat (Fagopyrum esculentum. The evaluations were done at 30, 75 and 225 days after sowing of the cover crops (DAS). The main growth weed species in the area were Cenchrus echinathus, Euphorbia heterophylla and Digitaria insularis. Fallow treatment showed greater number of weed species with density of 184 plants m-2, 9.0 species and with 527.8 g m-2 of dry matter mass at 225 DAS. In all treatments verified reduction in the density and mass of weeds dry matter compared to the fallow, with average of 30 plants m-2, 5.8 species and 7.9 g m-2 at 225 DAS, respectively. The use of cover crops is an important strategy for weed control in agricultural areas.

Does crop succession and nitrogen splitting fertilization change the technological quality of common bean?

ABSTRACT The crop succession and nitrogen splitting fertilization are managements that can affect the common bean technological quality and, consequently, the profitability of producer and the food biological value. The aim of this study was to evaluate whether crop succession and N splitting fertilization promote differences in the technological quality of common bean grains. The experiment was carried out during winter over two agricultural years in southeastern Brazil. A randomized block design was used in a split-plot scheme, with four replications. The plots were composed of three crop successional systems (maize sole, maize + Urochloa ruziziensis, U. ruziziensis sole) and the subplots contained nine combinations of N splitting fertilization at a rate of 90 kg·ha-1 N top-dressing in the phenological stages V3, V4, and R5 of the common bean and a control without fertilization. The evaluated variables were: sieve yield greater than or equal to 12 (SY ? 12), crude protein content, cooking time, and hydration ratio. Crop succession promotes differences in the technological quality of common bean; however, the N splitting fertilization did not change the technological attributes of grains. The highest technological quality of common bean was obtained after succession with U. ruziziensis sole, generating large size and crude protein content of grain, followed by the succession with maize + U. ruziziensis intercropping, and finally, the succession with maize sole. Therefore, the crop succession is a fundamental factor for obtaining common bean with higher technological quality, affecting the food biological value and the profitability of producers.