Red Oxisol Research Articles

Evaluation of the Structure of Dry Soil, Subjected to Dynamic Load in Different Managements

The structural evaluation of agricultural soil is essential for the performance and quality of production. Soils suffer surface consolidation when subjected to agricultural machinery traffic and alter their physical characteristics according to the management to which it is subjected. Therefore, this work aimed to evaluate the physical indices and surface consolidation of a red oxisol subjected to different loads and types of management. Undeformed soil samples were collected from three areas with different management systems: no-tillage, crop-livestock--forest integrated system (CLFI), and pasture area. Traffic simulations were conducted with application of dynamic loads, using 0 pass, 1 pass, and 2 passes (0, 108, and 216 kpa), evaluating the physical indices of the soil's natural specific weight (yn), dry apparent specific weight (yd), void index (n), and porosity (e). Subsequently, the samples were subjected to uniaxial compression tests using loads (108, 216, 432, 864, and 1500 Kpa) to verify the surface consolidation. The experiment was conducted in a completely randomized design, with a 3x3x5 factorial scheme in sub-subdivided plots. Thus, we verified that the no-tillage management system has a more porous soil due to its characteristics, presenting lower resistance and being better for planting. CLFI was characterized as a management that allowed the soil to be more resistant to the application of loads and, therefore, less porous. Pasture has an intermediate behavior.

Soil Solution Properties of Tropical Soils and Brachiaria Growth as Affected by Humic Acid Concentration

The soil solution is the compartment where plants uptake nutrients and this phase is in equilibrium with the soil solid phase. Changes in nutrient content and availability in the soil solution can vary among soil types in response to humic acid concentrations, thereby affecting Brachiaria growth. However, there are no studies demonstrating these effects of humic acid application on different soil types and how they affect Brachiaria growth. Thus, the aim of this study was to evaluate the effects of humic acid concentrations (0, 5, 10, 25, and 60 mg kg−1 carbon-humic acid) on Brachiaria brizantha growth and soil solution properties of contrasting tropical soils. Plants were grown for 35 days in greenhouse conditions in pots containing Sandy Entisol, Clayey (Red Oxisol), and Medium Texture (Red-Yellow Oxisol). Soil solution was assessed for pH, electrical conductivity (EC), carbon, and nutrient content. Shoot and root dry matter, as well as macro and micronutrients accumulation in the shoot, were determined. In a soil type-dependent effect, pH, EC, and concentrations of nutrients in solutions changed in response to carbon-humic acid concentration. In the less-buffered soils, Sandy Entisol and Red-Yellow Oxisol, the addition of 30–40 mg kg−1 carbon-humic acid increased root proliferation by 76–89%, while Brachiaria biomass produced in all soils increased by approximately 30%. Levels of carbon in solution were high (>580 mg L−1) and varied depending on the investigated soil type. Though solution carbon contents did not appear to be a driving factor controlling the positive effects of humic acid concentrations on Brachiaria dry matter, there was a direct relationship between other properties and nutrient content in the soil solution, and Brachiaria dry matter production.

Azospirillum brasilense Inoculation in a Maize–Urochloa–Rice Cropping System Promotes Soil Chemical and Biological Changes and Increases Productivity

Large quantities of cover crop residues in the soil, combined, or not, with the inoculation of seeds with diazotrophic bacteria, can increase organic matter (OM) and protect soil microorganisms, such as arbuscular mycorrhizal fungi (AMF) and dark septate endophytic (DSE) fungi. Thus, the use of these sustainable biotechnologies can benefit microbial interactions, soil fertility and rice production in the Brazilian Cerrado region. In this study, we evaluated the effects of maize and Urochloa ruziziensis, intercropped or individually, as cover crops and an inoculation of Azospirillum brasilense on the chemical (fertility) and biological (C–microbial biomass and C–CO2 released) attributes of soil and the effects of root colonization by AMF and DSE on the yield of rice grown in succession in highlands. The experiment was conducted under field conditions, in a typical dystrophic Red Oxisol. The experimental design consisted of randomized blocks arranged in strips, incorporating a combination of eight residual cover crops: ((1) maize, (2) maize–I (I = inoculation of seeds with A. brasilense), (3) Urochloa (U. ruziziensis), (4) Urochloa–I, (5) maize + Urochloa–I, (6) maize + Urochloa–I, (7) maize–I + Urochloa and (8) maize–I + Urochloa–I). This was accompanied by two treatments of rice as a successor crop (inoculated or not with A. brasilense), with four replicates, totaling 64 experimental units. A cover crop and rice seed inoculation prompted increases in OM and AMF relative to DSE, while the inoculation of rice, regardless of the cover crop treatment, increased the soil’s P content. The combination of maize + Urochloa–I and inoculated rice as the next crop generated increases in its sum of bases (SBs) and cation exchange capacity (CEC). There was a 19% increase in rice grain yields when the seed was inoculated.

AGRONOMIC EFFICIENCY OF REKAL REMINERALIZER IN SOYBEAN AND MAIZE CROPS

Remineralization regards using rocks as both conditioners and nutrient sources for agricultural soils; it also works as essential basis for degraded or depleted soil recovery. The aim of the present assay is to assess the performance of Rekal remineralizer and its effects on soybean and maize cultures, which were used as test plants. The following soil types were used in the experiment: Yellow Oxisol with sandy loam texture and Red Oxisol with clayey texture. The research was carried out in greenhouse, at the Agronomics School of Federal University of Goiás, Goiânia City, Goiás State. Experimental treatments consisted in using different Rekal remineralizer doses (0, 30, 60, 120 and 240 kg ha-1 K2O) to compare the results to those of FMX remineralizer products and potassium chloride (KCl), at the dose of 60 kg ha-1. Plant development variables (height, diameter and number of leaves), soil and leaf potassium content, calcium and magnesium content, CEC and soil base saturation, soybean grain yield, maize green mass yield and the relative efficiency of Rekal using in comparison to both FMX remineralizer and potassium chloride synthetic fertilizers were assessed. Results have shown that Rekal remineralizer presents agronomic efficiency comparable to that of KCl and FMX remineralizer. Using Rekal remineralizer can improve and keep important soil parameters, such as CEC, soil base saturation and calcium, magnesium and potassium content.

How substrate type and elevation drive woody communities and influence species ecological strategies in the Brazilian savanna at local scale

AbstractEnvironmental heterogeneity can influence the formation of different vegetation types, even at small spatial scales. However, little is known about the factors that drive communities at local scales and species' mechanisms to adapt to different environments. Here, we investigated the influence of local environmental conditions and spatiality on the floristic variation of woody vegetation and ecological strategies of shrub‐tree species in the Brazilian savanna. We sampled adjacent sites in three substrate types—deep soil at high altitude (in Red Oxisol, with vegetation locally called Typical Cerrado—TCRO), deep soil, sandy and at low elevation (Typical Cerrado in Entisol Quartzipsamment—TCEQ), and shallow soil with rocky outcrops at high elevation (in Entisol Lithic, with vegetation known locally as Rupestrian Cerrado—RCEL). At each environment, we inventoried the vegetation, analyzed the physical–chemical soil properties, and recorded the elevation and geographic coordinates. For the most representative species of each site and the most common one among the environments, we evaluated the functional attributes (leaf nutrient concentration, specific leaf area, and maximum population heights). We showed that substrate type and elevation explain most of the floristic variation at the local scale and that the low nutritional demand constitutes the main strategy used by the species in RCEL, while in TCEQ and TCRO, species are more efficient in resource acquisition. Our results revealed that local ecological factors and processes drive species distribution. Therefore, variations in vegetation, even at the local scale must be considered to conserve biodiversity effectively.

Eficiencia de diferentes tipos de inoculantes en el cultivo de soja

The inoculation of Bradyrhizobium specific for the soybean crop is an indispensable practice in the cultivation of this leguminous plant. In this study, traditional inoculation via seed was chosen. The experiment was carried out in a soil classified as red oxisol with medium texture in a completely randomized design (DIC), with 4 treatments and 7 repetitions. Each experimental unit was comprised of a 1m² plot, and the treatments analyzed were: Liquid inoculant (T1); Peat inoculant (T2); Liquid + peat inoculant (T3) and no inoculant (T4). The objective proposed in this study was to verify the need to use inoculants in soybean planting in areas where the crop has been cultivated for more than six years. According to the F test, there was a significant difference between the treatments, with T3 standing from among the others for root length, number of nodules and nitrogen concentration on the leaf. T2, although inferior to T3, showed better results than treatments T1 and T4. In the experimental conditions using the Brasmax Bônus8579IPRO cultivar, there was a significant difference in the use of the products, with emphasis on the liquid inoculation + peat (T3), presenting a higher frequency concentration in the plant leaf, obtaining an even greater number of nodules and root length. As the value of the F statistic for the variables average root length, average number of nodes and average leaf transmit nitrogen content exceeds the critical value at the 1% probability level (4.72), they are represented at this level (P < 0 ,01). As the calculated F values were greater than the tabulated F values for the three analyzed variables, we rejected the null hypothesis (H0), and concluded that the determining variables have different effects. Therefore, we can conclude that the most recommended for inoculation would be the use both products.

Spatial variability of dendrometric parameters in a native tree Mabea fistulifera Mart. and its relationship with soil physical properties

Mabea fistulifera Mart. (common name: canudo-de-pito) belongs to the Euphorbiaceae family and is a native tree species in Brazil showing a high potential to recover degraded lands. This study aimed to evaluate the distribution and spatial correlation between the dendrometric parameters of the M. fistulifera plants and the physical attributes of the soil through geostatistics. The study was carried out at the Paulista State University (UNESP), in the city of Selvíria, MS, Brazil, in a typical dystrophic Red Oxisol with a clayey texture. The following properties were analyzed: for soil, penetration resistance, gravimetric moisture, particle density, and, for plants, circumference and diameter at breast height (measured at 130 cm above the ground), tree height, and total volume of the tree. An experiment grid was introduced with 35 sample points spaced 13 m x 13 m. Two soil samples were taken at each point, at 0.00 - 0.10 m and 0.10 - 0.20 m depth. Descriptive data analysis and spatial dependence analysis were carried out through semivariogram adjustments and kriging maps. The dendrometric properties of the species M. fistulifera and the soil gravimetric moisture content showed spatial dependence. The spherical semivariogram model best explained the spatial structure of circumference at breast height, diameter at breast height, tree volume, and soil gravimetric moisture. There was an emphasis on the correlation between the total volume of the tree as a function of the diameter at breast height, showing a moderate spatial dependence. Furthermore, the tree diameter at breast height proved to be a good indicator for determining the total height of the M. fistulifera tree.

New approaches to the effects of Si on sugarcane ratoon under irrigation in Quartzipsamments, Eutrophic Red Oxisol, and Dystrophic Red Oxisol

BackgroundC:N:P homeostasis in plants guarantees optimal levels of these nutrients in plant metabolism. H However, one of the causes to the effects of deficit irrigation is the loss of C:N:P homeostasis in leaves and stems that causes reduction in the growth of sugarcane. Being able to measure the impact of water deficit on C:N:P homeostasis in plants from the stoichiometric ratios of the concentrations of these nutrients in leaves and stems. This loss causes a decrease in nutritional efficiency, but can be mitigated with the use of silicon. Silicon favors the homeostasis of these nutrients and crop productivity. The magnitude of this benefit depends on the absorption of Si by the plant and Si availability in the soil, which varies with the type of soil used. Thus, this study aims to evaluate whether the application of Si via fertigation is efficient in increasing the absorption of Si and whether it is capable of modifying the homeostatic balance of C:N:P of the plant, causing an increase in nutritional efficiency and consequently in the production of biomass in leaves and stems of sugarcane ratoon cultivated with deficient and adequate irrigations in different tropical soils.ResultsWater deficit caused biological losses in concentrations and accumulation of C, N, and P, and reduced the nutrient use efficiency and biomass production of sugarcane plants cultivated in three tropical soils due to disturbances in the stoichiometric homeostasis of C:N:P. The application of Si increased the concentration and accumulation of Si, C, N, and P and their use efficiency and reduced the biological damage caused by water deficit due to the modification of homeostatic balance of C:N:P by ensuring sustainability of the production of sugarcane biomass in tropical soils. However, the intensity of attenuation of such deleterious effects stood out in plants cultivated in Eutrophic Red Oxisols. Si contributed biologically by improving the performance of sugarcane ratoon with an adequate irrigation due to the optimization of stoichiometric ratios of C:N:P; increased the accumulation and the use efficiency of C, N, and P, and promoted production gains in biomass of sugarcane in three tropical soils.ConclusionOur study shows that fertigation with Si can mitigate the deleterious effects of deficient irrigation or potentiate the beneficial effects using an adequate irrigation system due to the induction of a new stoichiometric homeostasis of C:N:P, which in turn improves the nutritional efficiency of sugarcane cultivated in tropical soils.

Micronutrients Content in Guava Seedlings after Variations in Phosphorus Sources, Liming, and Soil Types

ABSTRACT Guava is one of the most important fruits in the Brazilian export market. The objective of this work was to evaluate the effects of liming and phosphorus (P) sources on micronutrients content in guava seedlings. The experimental design was completely randomized in a factorial scheme (2 × 3 × 3) comprising two dolomite limestone rates (0 and 5 Mg ha−1), three soil types (Typical Red Oxisol, Typical Yellow Oxisol, and Typical Yellow Ultisol), and three P sources (Arad rock phosphate, thermophosphate ‘Yoorin,’ and triple superphosphate) at 150 mg kg−1, with three replicates. Boron [B], copper [Cu], zinc [Zn], iron [Fe], and manganese [Mn] concentrations in guava seedling leaves and stems were affected by liming, by the P source, and by the soil type. Limestone and P sources altered the B, Cu, Zn, Fe, and Mn concentrations in leaves and stems of guava seedlings in each of the three evaluated soil types. Due to its low solubility, and regardless of soil type and liming, Arad rock phosphate was less effective than triple super phosphate as a P source for guava seedlings.

Utilização de resíduo de sangue como fonte alternativa de fósforo no cultivo de girassol (Helianthus annuus L.)

ABSTRACT The aim of this work was to increase the aerial part, biometry, and yield of achenes from sunflower plants on the effect of increasing doses of blood residue, as an alternative source of phosphorus (P), in a clayey-textured red Oxisol. The experimental design used was randomized blocks, with six treatments and four replications. The treatments consisted of five doses of blood residue (0, 6, 12, 24 and 48m3 ha-1) and a control treatment that received phosphate chemical fertilization, 80kg ha-1 of P2O5. The increasing doses of blood residue and chemical fertilization do not show disproportionality for P concentration in soil, leaf, plant height (PH), stem diameter (SD), chapter diameter (CD) and achene production. The analysis of the principal component (PC) revealed that the first PC presents the greatest accumulated variation (74%). Based on the first PC, the dose of 12m-3 ha-1 has greater influence for PH, SC, and CD. Due to the greater influence on the biometric characteristics of sunflower plants, the blood residue (12m-3 ha-1 = 98.4kg P ha-1), can be used as an alternative source of phosphorus for the cultivation of sunflower in clayey oxisols.

Effect of liming and phosphorus sources on soil fertility, growth, and nutritional status of guava seedlings in three tropical soils

Guava (Psidium guajava L.) is a widely consumed tropical fruit. Although its production is expanding, there are few studies on phosphorus (P) source efficiency in soils with different acidity levels. The objective of this study was to evaluate the effect of liming and P source on the nutritional status and growth of guava seedlings in three soil types. The experimental arrangement was completely randomized in a factorial scheme (2 × 3 × 3), consisting of two limestone rates (0.0 and 5.0 Mg ha−1), three soil types (typical Red Oxisol, typical Yellow Oxisol, and typical Yellow Ultisol), and three P sources (natural Arad phosphate, Yoorin thermophosphate, and triple superphosphate) with three replicates. Liming and P source influenced soil chemical attributes, as well as the growth and nutrient concentrations in the tissues of guava seedlings. Mehlich 1 extractant gave the highest available P levels in the three soils compared with Mehlich 3 and ion exchange resin.

Management of Soil Acidity and Its Relations With Soybean Productivity in Brazilian Savanna

The soils of Brazilian Savanna, naturally, present acidity problems, making correction practices fundamental to ensure production. Even with so many years since the introduction of agriculture, some soil correction practices are still misused. Thus, the objective was to evaluate soybean yield and chemical changes in a Red Oxisol in the Brazilian Savanna with the use of limestone, associated or not with gypsum, applied superficially and incorporated by harrow and moldboard plow. The experiment was conducted under field conditions, in Rio Verde-GO, cultivating soybeans in the 2015/2016 and 2016/1017 harvests. The experimental design was in randomized blocks, with four replications, with treatments arranged in a 3 × 3 factorial scheme. The first factor refers to the application of superficial limestone and incorporated by harrow and moldboard plow. The second factor was the presence or absence of limestone and/or gypsum (0 + 0; 0.875 + 0 and 0.875 + 1.75 t ha-1). Plant height, number of pods per plant, productivity, pH, Al, CTC, Ca, Mg and V were evaluated, in soil depths of 0-0.2 and 0.2-0.4 m. In the 2016/2017 harvest, the characteristics of pH, CTC, V and contents of Ca, Mg and Al were influenced by the methods of application of limestone and by its use, associated or not with gypsum. There was an increase in pH on the soil surface with the use of limestone and on the subsurface with the use of limestone and gypsum. The moldboard plow provided increases in the contents of Ca and Mg in the soil in comparison to surface application. The moldboard plow incresed in soybean yield, in the second crop, with and without association of gypsum with limestone.

Using Arduino sensors to monitor vacuum gauge and soil water moisture

Sensors associated with the Arduino board can be an alternative to traditional sensors. The objective of this study was to calibrate a capacitive sensor to measure soil moisture and determine the soil water retention curve (< 100 kPa) using the MPX5100DP pressure transducer in conjunction with capacitive sensor measurements. The soil used was Red Oxisol, which had a clay texture and a bulk density of 1.20 Mg m−3. The model 𝑦𝑦=𝑎𝑎−𝑏𝑏𝑐𝑐𝑥𝑥 was fitted to the capacitive sensor data, which had the following statistical parameters: 9% (MAPE, mean absolute percentage error), 0.025 (RMSE, root-mean-square error), 0.97 (d), and 0.93 (𝑅𝑅2). In general, the error for the retention curves obtained with the capacitive sensor and that obtained by weighing was 0.025 (RMSE). Despite the slight tendency of the capacitive sensor to underestimate the highest values of soil moisture, these sensors can be used as an alternative for measuring soil moisture and water tension.

Single cultivation versus sweet potato and popcorn intercropping: benefits over edaphic fauna in ecological-based system

The objective of this study was to evaluate the diversity and abundance of edaphic fauna organisms in single and intercropped systems of sweet potato (Ipomoea batatas) and ecologically-based popcorn (Zea mays) in Red Oxisol, in the Northwest region of the state of Rio Grande do Sul, Brazil. Four sweet potato cultivars were used in single systems and intercropped with popcorn: BRS Amélia, BRS Rubissol, BRS Cuia and Crioula. The soil fauna assessment was carried out using PROVID-type traps. Richness, abundance and the dominance indices of Shannon (H’) and Simpson (D) were determined. The orders Coleoptera, Hymenoptera, Collembola and Orthoptera, were dominant in both cultivation systems. The single cultivation showed a greater number of organisms in the orders Isopoda and Collembola, whereas in the intercropped system, the orders Lepidoptera and Hymenoptera stood out. The intercropping cultivation of sweet potato and popcorn shows highest diversity and abundance of soil organisms compared to the single cultivation.

A Mottled, Non-Lithified Paleosol in Brazil: Diagnosis by Morphological and Mineralogical Features

The identification of paleosols is difficult when no buried horizons or lithification occur. Here, we described the identification of a possible paleosol, its characterization, and which features supported its positive diagnosis. In a construction site, a vertical cut exposed an unusual red–yellow mottling with massive structure and channels (probably faunal), in contrast with the overlying homogeneous red Oxisol with fine granular structure. A similar but more deferrified section with white–yellow mottling also occurred nearby, and both were sampled as large clods. In thin sections, many oriented clay coatings occur along channel voids, suggesting illuviation, as well as dissolving Fe nodules and Mn coatings along planar and channel voids. X-ray diffraction showed a clay dominated by kaolinite, traces of illite, and absence of gibbsite, again contrasting with the gibsitic-kaolinitic clay of the Oxisol. We confirmed the diagnosis of a Paleoultisol due to the following incompatibilities with the overlying Oxisol: (1) massive, apedal structure, and higher bulk density; (2) clay coatings indicative of illuviation as key soil-forming process; (3) low clay contents in particle-size analysis due to cementation; (4) very low organic carbon consistent with long-term inhumation; and (5) kaolinitic–illitic clay. The unusual granular microstructure of the B horizon of the Oxisol is partly derived from disintegration and desilication of the Paleoultisol.

Sources and doses of nitrogen in plant cane production and residual effect on the first ratoon of sugarcane in a savannah Red Oxisol

The expansion of sugarcane cultivation, especially in areas with low natural soil fertility, such as savannah regions, requires greater efficiency in the application of nutrients, mainly nitrogen (N). The objectives of this study were to evaluate the effects of the application of different sources and doses of nitrogen on the dry matter yield and productivity of sugarcane in the plant cane cycle and the residual effect of such application on the first ratoon cycle of sugarcane (var. SP80-1816) cultivated in a dystrophic Red Oxisol. The experimental design was a randomized complete block design analyzed in a factorial scheme of 2 × 4 with three replications. The evaluated factors consisted of two sources of N (ammonium nitrate (AN) and urea (U)) and four doses of N (0, 60, 120 and 180 kg ha-1). Samples of the aerial part of the sugarcane were collected. The structural components of the aerial part were separated, and the leaf dry matter (LDM), stalk dry matter (SDM) and dry matter of the aerial part (DMAP) were analyzed. The productivity of stalks (PS) was determined by weighing all stalks present in the useful area of each plot. In the plant cane cycle, AN resulted in greater gains in the SDM and PS of sugarcane than did U. In the first ratoon cycle, a residual effect was observed in response to N application, which showed an increase in SDM and PS. Under the conditions of this study, to achieve a higher PS in both cycles, the application of 180 kg N ha-1 is recommended

DRY MATTER ACCUMULATION AND SUGAR AND ALCOHOL YIELD OF SUGARCANE SUBMITTED TO NITROGEN SOURCES AND DOSES

The study aimed to evaluate the nitrogen sources and doses application effects on the dry matter production and the sugar and alcohol gross yield of sugarcane (SP80-1816) in the cane-plant cycle in a dystrophic Red Oxisol. The experiment was conducted in the Fazenda Rio Paraiso II field, belonging to Usina Raízen, in Jataí - GO. The experimental design used was randomized blocks, arranged in a factorial scheme (2 x 4), with three replications. The treatments consisted of two nitrogen sources (urea and ammonium nitrate) and four nitrogen doses (0, 60, 120, and 180 kg ha-1). Dry matter variables were analyzed in sub-subdivided plots, as four evaluation periods were added (210, 250, 290, and 330 days after planting). The evaluation periods influenced sugarcane dry matter, and urea favored these variables to the ammonium nitrate's detriment. In contrast, the opposite occurred for stalk yield and sugar and alcohol yields, in which ammonium nitrate provided greater increments. The increase in nitrogen doses provided linear gains in practically all studied variables.

A Novel Technology for Processing Urban Waste Compost as a Fast-Releasing Nitrogen Source to Improve Soil Properties and Broccoli and Lettuce Production

This study evaluated nitrogen (N) mineralization dynamics in three soils after the addition of heat-treated urban waste amendments or urban waste compost (UWC). The effects of UWC and urea on soil properties and broccoli and lettuce production were compared. The first N mineralization experiment was conducted in a factorial arrangement (4 × 3), as a randomized complete block design (RCBD), with three replicates. Four UWC doses: 12.5, 25.0, 37.5, and 50.0 mg dm−3 were applied to three soils: sandy Ustoxic Quartzipsamment (QS), intermediate-texture red Ultisol (US), and clayey red Oxisol (OS), during eight incubation periods (0, 7, 14, 28, 42, 56, 70, and 84 days). In the second experiment, the effects of UWC and urea fertilizer on soil properties were compared. The growth of broccoli and lettuce plants was evaluated (experiments 3 and 4). The treatments (Experiments 2–4) followed a factorial arrangement (4 × 2; RCBD; three replicates), using OS soil. Four N doses (as for experiment 1) were combined with two N sources (UWC and urea). The processed UWC application proportionally increased the N mineralization rate by 72% in QS, 54% in US, and 66% in OS. Furthermore, UWC application enhanced soil properties (pH and nutrient availability), compared with urea fertilizer, and improved N uptake, resulting in higher fresh biomass production in broccoli and lettuce plants (50.0 and 37.5 mg dm−3, respectively). Our findings suggest that heat-treated UWC is an economical, viable, and efficient fertilizer to improve soil properties and short-cycle vegetable crop productivity.

NITROGEN ACCUMULATION AND EXPORT BY COMMON BEAN AS A FUNCTION OF STRAW AND N SPLITTING IN NO-TILLAGE SYSTEM

ABSTRACT Determining nitrogen (N) accumulation and export by common bean as a function of straw and of the splitting of this nutrient is very important, aiming at the management and sustainability of agricultural systems. This study aimed to determine the N accumulation and export by common bean as a function of Zea mays and Urochloa ruziziensis grass straw (maize, maize/U. ruziziensis intercropping and U. ruziziensis) and splitting of top-dressing N fertilization. The experiment was conducted in Jaboticabal-SP-Brazil, during the 2012/13 crop season, in a Red Eutrophic Oxisol (Eutrudox) in no-tillage under irrigation. The experimental design was a randomized block with split plots with four replicates, totaling 120 subplots sized in 25m2 each. The plots consisted of the cropping systems prior to common bean: maize, maize/ U. ruziziensis intercropping and U. ruziziensis. The subplots were composed of ten top-dressing N fertilization splitting schemes (NS) at the phenological stages V3, V4 and R5 in different combinations. Common bean grain yield differs among cropping systems and as a function of top-dressed N split application. U. ruziziensis grass as single crop promotes greater N accumulation in common bean shoots compared to maize and its intercropping with U. ruziziensis grass. Regardless the cropping system, top-dressing N application in a single dose (90 kg ha-1) at V4 leads to similar accumulations and exports to those found in the absence of N fertilization. Splitting schemes with N application at the R5 stage increase the exports of this nutrient by common bean in succession to maize and its intercropping with U. ruziziensis grass.

Coffee seedling growthafter legume cultivation in soils with contrasting phosphorus contents

Coffee seedling growth depends on soil phosphorus (P) availability and may be influenced by from pre-cultivation with legumes. Efficient and sustainable ways to increase the bioavailability of P through the recovery of P adsorbed by the soil matrix should be sought. This study proposed to evaluate the growth and P-use efficiency of coffee seedlings cultivated in soils with different P availability after cultivation with legumes. The experiment was carried out in a fully randomized design. Treatments were arranged in a factorial scheme [(2 x 4) + 1]: two soil types, pre-cultivation with four legume species, and one control (withoutpre-cultivation). The studied soils comprised a Typical Acriferic Red Oxisol (LVwf) with low-P availability and a Typical Chernossolic Litholytic Entisol (RLm) with high-P availability. The legume species Crotalaria juncea, Cajanus cajan, Canavalia ensiformis, and Mucuna aterrima were previously cultivated for 45 days. Afterwards, coffee seedlings were transplanted to the pots, which were then grown for 120 days until evaluations. We assessed the following parameters: plant height (H), stem diameter (SD), shoot dry matter (SDM), root dry matter (RDM), total dry matter (TDM), and shoot contents of macronutrients. Our results showed that coffee seedlings grew more when cultivated in the high-P availability soil, with increments of 13.05% in H, 4.86% in SD, 46.98% in SDM, 17.61% in RDM, and 41.80% in TDM.We also observed an increase of 28.09% in shoot P contents for coffee seedlings grown in RLm. Moreover, pre-cultivationwith C. juncea provided the largest increases in coffee seedling growth compared to the control. When grown after C. ensiformis cultivation, coffee seedlings had the highest shoot contents of P, Ca, Mg, and S, which, compared to control, increased by 45%, 39%, 18%, and 17%, respectively. Keywords: Canavalia ensiformis; Crotalaria juncea; Coffea arabica; phosphate fertilization; nutritional efficiency.