Clayey Texture Research Articles

The Effects of Potassium Dose, Timing, and Source in Soybean Crops in Brazilian Savannah Oxisol

In Brazil, several silicic rocks can be used as powder-based K sources, which can reduce production costs in agriculture. The optimized supply of K not only increases yield but also contributes to soil fertility preservation and long-term sustainability by curtailing nutrient losses and reducing the risk of nutrient imbalances. Therefore, this study aimed to investigate the effects of K application timing, source, and doses on nodulation, productive components, and productivity of soybeans in a not-tillage system in the Savannah. The experiment was carried out in the field, for two years, in an Oxisol, with a clayey texture. The experimental design was in random blocks, in a 2 × 4 × 3 factorial scheme, as follows: two application timings (early and sowing), four K2O rates (0, 40, 80, and 120 kg ha−1), and three sources (KCl, Potasil, and Ekosil), with four replicates. Potassium fertilizer was broadcasted on the soil without incorporation into the soil. Due to the interactions between doses and K2O sources, there was a linear adjustment for KCl sources, the higher the dose, the lower the nodule mass. Also, for nodule mass, the interaction between dose and application time was significant for the early application of the Ecosil and Potasil sources for 80 kg ha−1. The highest estimated soybean grain productivity was 3262 kg ha−1 with 78 kg ha−1 of K2O, being the most suitable for growing soybeans under a no-tillage system.

Components of High-Yielding Cotton Grown in Rain-Fed Conditions in the Brazilian Cerrado

Brazil leads globally in achieving high lint yields for rain-fed cotton in large-scale fields, with about 92% of its cotton area unirrigated. This study hypothesized that cotton could achieve high yields when favorable climate conditions and management practices favor high fruit load. The objective was to analyze the impact of these factors on cotton yields by examining two commercial fields in Brazil in the same climatic zone (Aw, Koppen)—one in Sapezal (SPZ) and the other in Riachão das Neves (RN). The SPZ field (cv. TMG 47B2RF) spanned 20 hectares, while the RN field (cv. FM 974GLT) covered 90 hectares. The soils of both fields were classified as oxisols, with SPZ possessing a clayey texture and RN a sandy loam texture. The findings indicate that the high lint cotton yields—3111 kg·ha⁻1 in SPZ and 3239 kg·ha⁻1 in RN—were achieved through a combination of ideal weather conditions, high-quality soil, and effective management practices, which favored boll retention, and an optimal plant architecture with short stature (<1.1 m), 19–22 nodes, and ~165 bolls m−2. Boll weights averaged 1.85–1.91 g of lint, and fruit retention rates were 61.6% in SPZ and 66.2% in RN. The study reveals a significant yield gap compared to Brazil’s average lint cotton yield (~1900 kg·ha⁻1) and other high-yield commercial fields (~3500–3900 kg·ha⁻1 of lint). The results underscore that bridging this gap—ranging from 1200 to 2000 kg·ha⁻1—could enhance the sustainability of cotton farming in Brazil by maximizing existing cultivated areas. Ultimately, the insights from this study highlight the role of combining climate suitability, management practices, and soil quality improvement to achieve higher cotton productivity and reduce environmental pressures from agricultural expansion.

CHARACTERIZATION OF RUNOFF ON AGRICULTURAL SOILS IN THE BANDAMA BLANC WATER-SHED, NORTHERN IVORY COAST, USING THE SCS-CN METHOD WITH GEOGRAPHIC INFOR-MATION SYSTEM (GIS) TOOLS

This study focused on the characterization of runoff on agricultural soils in theBandama Blanc watershed in Badikaha, Northern Cote dIvoire. The objective was to highlight the influence of land use change on runoff. To achieve this, soil data and profiles were utilized, allowing for the analysis of the hydrological properties and characteristics of the soils in the study area using the SCS (U.S.D.A.) method. The study revealed a continuous increase in the proportions of built-up/bare soil and cultivated areas over three study periods. The respective proportions were 16%, 27%, and 48% for built-up/bare soil, and 11%, 17%, and 33% for cultivated areas in the years 1986, 2004, and 2023. Additionally, it showed that the soils in the watershed predominantly exhibit clayey texture. These findings, combined with curve numbers (CN), highlighted significant runoff occurring in the study area, with average CN values of 70.57, 57.14, and 66.67 for 1986, 2004, and 2023, respectively. It follows from these results that runoff is more pronounced in urban areas, bare soils, highly mechanized agricultural environments, and watercourses. This study demonstrated that GIS and remote sensing techniques enable large-scale determination of runoff using the SCS-CN method. Furthermore, it serves as a simple and cost-effective tool for modeling runoff.

Physical and Geochemical Characterisation of Pongo Pitti and Bossambo Farm Clays (Littoral Region, Cameroon) for use in Ceramics

The main objective of this work is to discern the physico-chemical and mechanical behavior of the Pongo Pitti and Bossambo Farm clay formations, located on either side of the Sanaga river in the littoral region of Cameroon. To achieve this, two field campaigns and laboratory works were carried out. Four clay materials were collected and brought back to the laboratory. The laboratory investigations involved physico-mechanical and geochemical analyses, followed by ceramic testing. The materials studied have a clayey texture, with clay percentages ranging from 26.89% to 80.3%, silt from 13.2% to 57.6% and sand from 1.58% to 47.26%. The plasticity index ranges from 11.9% to 24.2%. From a geochemical standpoint, the materials studied show a predominance of silica (49.6% to 63.5%), alumina (20.5% to 27.1%) and iron (2.39% to 8.6%), with the SiO2/Al2O3 ratio varying from 1.96 to 3.1. The Al2O3/Fe2O3 ratio is 8.4 for Pongo Pitti clays and 2.9 for Bossambo Farm clays. The geochemical weathering indices (ICV, CIA, PIA, CIW, CIW) show a high degree of weathering, with values in excess of 90%. Alkali and alkaline-earth proportions are lower, and the K2O/Na2O ratio varies between 8.45 and 14.24, showing an enrichment of potassium in relation to sodium. Lantane is the most abundant rare-earth element (323.84 ppm). The REE study shows a predominance of light REEs over heavy REEs (LREE/HREE~4.51) and a negative Europium anomaly. Infrared spectroscopy showed poor kaolinite crystallinity. Mechanically, the specimens studied, fired at temperatures ranging from 950℃ to 1050℃ showed good cohesion and metallic soundness. Linear shrinkage was 4.8%. Mass loss increases with temperature. Its value is 12.5% for Pongo Pitti materials and 8.5% for Bossambo Farm materials. Water absorption decreases with temperature and is 20.27% for Pongo Pitti samples and 15.79% for Bossambo Farm samples. Bulk density increases with temperature (2.11 at 950℃ to 2.51 at 1050℃). Flexural strength increases with temperature and is 6.66 MPa for materials from Pongo Pitti and 8.89 MPa for those from Bossambo Farm. These materials can be used to make fired bricks and roof tiles, and Pongo Pitti materials can be used to make refractory ceramics

Impacts of Varying Sowing Dates on the Profitability and Production of Cultivars of Pigeonpea (Cajanus cajan L. Mill sp.)

At the experimental farm of the College of Agriculture, Badnapur, VNMKV, Parbhani, a suitable range of field experiments were done during the kharif season, with an optimal time of sowing. The experiment was carried out using five varieties in the sub plot, V1-BSMR-736, V2-BSMR-853, V3-BDN-711, V4-BDN-708, and V5-Vipula, and four sowing dates in the main plot, D1: (15 th June), D2: (30 th June), D3: (15 th July), and D4: (30th July). The soil had a medium-black color, a clayey texture, a high base saturation level, an alkaline reaction, and a higher concentration of total soluble salts. It also had low levels of nitrogen and phosphorus and high levels of potassium and lime. The dibbling method of sowing was used. According to the experiment's results, sowing of pigeonpea on June 15 th was the best date to achieve greater yield metrics, specifically number of pods per plant, pod weight plant-1 (g), grain weight plant-1 (g), and test weight (g). in addition to economic indicators including GMR (119080 Rs ha-1), NMR (96573 Rs ha-1), and B:C (5.29), in addition to harvest index (HI), biological yield (kg ha-1) and seed yield (kg ha-1). Comparatively speaking to the other kinds, the pigeonpea variety BSMR-736 was shown to be very prolific.

Nitrogen fertilizers affecting the efficiency of mineral and organic phosphorus fertilizers in tropical soils cultivated with maize

Most conventional phosphorous (P) fertilizers are highly soluble, which favors P retention in the solid phase of the soil, and this condition hinders P availability to plants. Alternative P fertilizers, such as organominerals and struvite, have a slow release of nutrients into the soil, which in turn favors P uptake by plants; nevertheless, soil acidification caused by nitrogen (N) fertilizers can reduce P availability in the soil. In his study, we assessed the effect of N fertilizers on P availability for maize (Zea mays) grown in tropical soils with alternative P fertilizers. An experiment was set up in columns under greenhouse conditions with maize in two cultivation cycles in two soils with contrasting textures (medium and clayey textures), two N fertilizers (calcium nitrate - CN - and ammonium sulfate - AS), three P fertilizers (triple superphosphate - TSP -, organomineral - OM - and struvite - ST), and a control treatment (without addition of P and N fertilizers). At 45 days after emergence, we measured the biomass production and the N and P contents in plants to calculate fertilization efficiency as well as the soil P content. AS promoted the highest aboveground N accumulation, whereas the highest efficiency was obtained with CN. The alternative P sources did not differ in terms of P availability when combined with both N sources. Soil textures were sensitive to fertilizer combination. Further studies are needed to assess struvite interaction with other elements in the soil and the P release kinetics to plants.

Soil carbon stocks as affected by land-use changes across the Pampa of southern Brazil

ABSTRACT The “campos” of the Pampa are unique Brazilian ecosystems, which provide key environmental services, including C storage. These grassy ecosystems have been rapidly converted to intensive land-uses, mainly intensive grain crops (soybeans) and Eucalyptus silviculture. These new land-uses could decrease soil C stocks, depending on soil management. This study aimed to assess soil organic carbon (SOC) changes after the conversion of native grasslands to cropland (soybeans/cover crops under no-tillage) and forestry (Eucalyptus). Eight representative sites in this biome were selected for soil sampling (Alegrete-ALE, Aceguá-ACE, Jari-JAR, Jaguarão-JAG, Pinheiro Machado-PIM, Lavras-LAV, Santo Antônio das Missões-SAM, São Gabriel-SAG). Soil sampling was conducted in dug pits (0.30 m wide × 0.30 m long × 0.40 m depth) spaced by 50 m at each site, to 0.30 m depth. Soil bulk density and SOC were obtained by samples obtained with volumetric rings. Soil organic C was analyzed by dry combustion. Soil C stocks were calculated per layer and cumulatively (0.00-0.20 and 0.00-0.30 m). Soil C content was higher under grasslands in soils from sites with finer, clayey texture (ACE, JAG), and lower in soils at sites with sandier topsoil. Land-use conversion to silviculture and cropland minimally affected SOC stocks. The same pattern was observed with soil N, because of the tight connection between C and N cycles. Soil bulk density was similar across sites and layers, but higher values were measured in sites with coarser texture. Mean SOC stock of the grassland sites was 62 ± 24.6 Mg ha -1 , similar to 66 Mg ha -1 reported for grasslands soils of Rio Grande do Sul State, and higher than that reported by IPCC for this region (55 ± 4.4 Mg ha -1 ). Adopting these default values would lead to underestimation of baseline SOC stocks in the region. Land-use conversion to cropland did not affect SOC stocks significantly, probably because of the adoption of no-tillage system with winter cover crops. Soil C stocks were lower in Eucalyptus stands in the 0.00-0.30 m soil layer, which could be attributed to intensive soil management at planting and lower soil fertility in some sites. This lack of effect of conversion on soil C was attributed to the short time since conversion and adoption of soil conservation practices (no-tillage) in cropland. The study contributed to reduce existing soil data gaps in the region and supports Brazilian public initiatives like the ABC Program and National Greenhouse Gas Inventories.

Can hydraulic-energy-indices be effectively used to describe the saturated hydraulic conductivity?

The saturated hydraulic conductivity (Ks) and water retention curve (SWRC) parameters are important properties for simulating soil hydrological processes and characterizing soil conservation around the world. Therefore, Ks and SWRC are related with the soil physical quality (SPQ) and several SPQ indices can be derived from SWRC, such as the pore size distribution, relative field capacity, plant available water, drainable porosity, and soil hydraulic-energy indices (SHEI). It is well known that the soil structure can be assessed by using SHEI, but a possible physical relationship between Ks and SHEI was not examined yet. Therefore, the objective of this study was to investigate the behavior of Ks as function of SHEI for several soil textural classes. If this relationship be proved, then SHEI might be applied to improve the Ks prediction by PTF models. In this work, a data set of 395 measured SWRC's were fitted to the vG equation to obtain the SHEI to verify whether they are statistically correlated and physically dependent on Ks. The resulting parametric and non-parametric correlation results were split up according to six textural classes. The significant influence of Ks on at least one of the absolute SHEI (Aa or WRa) was verified on the numerical scale when all textures were grouped and on numerical and pF scales for clayey and silty textures. Ks showed significant impact on Aa and WRa indices in four textural classes. Furthermore, Ks had influence on the sum Aa + WRa denoted in pF scale for five of the six textural classes, with a significant linear correlation in the clayey texture when log (Aa + WRa) was applied. The significant and high correlation of Ks on the ratios WRa/AWC and Aa/φD was also observed in four of the six classes, and therefore the use of these indices is recommended for the development of PTFs for Ks prediction.

Study of some fertility characteristics of soils with different agricultural uses in the Aqra Region/Duhok

A study was conducted in the Aqra region to investigate the fertility characteristics of soils with different agricultural uses. The study included (40) sites, representing surface soils (0-30 cm). Soil samples were transported to the laboratory for physical and chemical analyses. The results showed that the majority of the studied soils were heavy soils with clayey texture (C) to clay loam texture (CL) and sandy clay loam texture (SCL). The pH values were mostly neutral in specific sites and slightly alkaline in most of the studied sites, Nitrogen values ranged between (6.27 – 43.90) ppm. Phosphorus values ranged between (1.05– 30.56) ppm, and it is natural for phosphorus dissolution to decrease due to plant absorption, adsorption, and fixation over time. This indicates a significant consumption of phosphorus in the soil, possibly attributed to elevated temperatures at the end of the season and reduced irrigation operations before harvest, leading to decreased phosphorus dissolution and increased fixation. The ratios of N in Kriging ranged between (27.44 - 32.61) represented the majority of the studied area, while he P for the first five categories ranged through the program between (1.05-9.70). and K for rest of study sites had low and variable values, as they appeared in red and light yellow, and their values ranged between (190 - 374).

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.

Metagenomics and vegetative growth of Salvia hispanica inoculated with Trichoderma harzianum.

The soil is a dynamic environment, influenced by abiotic and biotic factors, which can result in changes in plant development. This study aimed to assess the impact on vegetative growth of chia (Salvia hispanica L) inoculated with Trichoderma harzianum and on the rhizosphere microbiome. The experimentation was conducted in a greenhouse under controlled conditions growing chia plants in pots containing soil with a clayey texture. Different concentrations of T. harzianum (0; 2.5; 5.0; 10.0; 20.0 µL. g-1 of seed) were applied to the chia seeds before planting. Morphological parameters, including plant height (cm), number of branches, stem diameter (mm), number of days to flowering and shoot and root dry masses (g) were quantitatively assessed. After the cultivation period, soil samples from the rhizosphere region were collected for subsequent chemical and metagenomic analyses. These samples were also compared with the control soil, collected before installing the experiment. The results showed that increasing doses of T. harzianum promoted a significant increase in the diameter of the stem, number of branches, dry biomass of the root system and the number of days to flowering, without modifying the overall height of the plants. Soil metagenomics indicated that T. harzianum inoculation modified the microbial diversity of the rhizosphere environment, with more pronounced effects observed in samples treated with higher concentrations of the inoculant. Furthermore, there were changes in the chemical composition and enzymes related to soil quality in correlation with the concentrations of the applied inoculant. This study demonstrated that inoculating chia seeds with T. harzianum not only promotes specific morphogenetic characteristics of the plant, but it also has a significant impact on the microbial diversity and biochemical functionality of the soil, including an observed increase in the populations of T. harzianum and T. asperellum.

Soil fertility status, productivity challenges, and solutions in rice farming landscapes of Azerbaijan

Rice, a fundamental staple globally, plays a pivotal role in addressing food security and nutrition. This study explores the intricate interplay between soil characteristics, productivity challenges, and solutions in Azerbaijan's rice farming landscapes, acknowledging the agricultural importance of rice and its contribution to human nutrition. This study aims to assess the physical and chemical properties of soil samples from Azerbaijan's rice cultivation areas, with a focus on nutrient content and the identification of elements limiting productivity and plant nutrition. By synthesizing these perspectives, the study enriches the understanding of the complex relationship between soil fertility class and rice productivity, offering insights for sustainable rice farming. Soil samples were collected from representative rice fields across Azerbaijan and analyzed for various parameters, including soil texture, pH, electrical conductivity, organic matter, and nutrient content. The soil sampling and preparation process maintained the integrity of collected samples, providing a reliable basis for scientific analysis. The results reveal diverse soil properties, with clayey texture prevailing. Soil acidity, salinity, and nutrient deficiencies pose challenges, emphasizing the need for corrective measures. The majority of soils exhibit unsuitable pH levels and elevated sodium content, necessitating interventions such as soil acidification and sodicity remediation. Soil salinity issues highlight the importance of drainage and leaching practices. Low organic matter and nutrient deficiencies, particularly zinc and manganese, underscore the need for targeted interventions, including foliar applications. Overall, Azerbaijan's rice-cultivated areas face challenges related to soil fertility, salinity, and nutrient deficiencies, impacting productivity. Corrective measures, such as soil reclamation, proper fertilization, and foliar applications, are crucial for enhancing crop yields. The study contributes valuable insights for local practices and the broader global pursuit of sustainable rice farming, emphasizing the importance of tailored strategies in addressing specific regional challenges.

EVALUATION OF THE BEHAVIOR OF RUBBER TEAS IN THE MARGINAL ZONE OF COTE DIVOIRE: CASE OF THE LOCALITIES OF MAN, TOUMODI AND PRIKRO

For a better orientation of Ivorian rubber cultivation in new areas of occupation, a study with the main objective of evaluating the behavior of rubber trees, with a view to better orientation of the extension of this culture was undertaken in the localities of Man, Toumodi and Prikro. The plant material used was rubber tree clones. During this study, the methodology consisted of evaluatingthe evolution of trees at 1.7m from the ground for mature plants and 1m from the ground for immature plants by measuring the circumference of the trees planted with a tape measure on different biotopes and soil textures previously defined. Production, dry notch rate and dry notch length of mature trees was also measured on the same parameters of the previous crop and texture. The results revealed thatthe previous cultivation of the rubber plots influences the mortality rate of the plants with a low rate observed in Man (17.30%) on the previous forest, also the trees had good growth on this previous one in Man (8.5cm.year-1) and Prikro (9cm.year-1). At ground level, the plants had a better level of radial growth in the localities of Man (8.30 and 9.06 cm.year-1) and Prikro (8.01 cm.year-1) with a more texture clayey (25% < clay < 50%). The average rubber production was also better in Man on the previous forest crop (63.85 ± 15.1 g.a-1s-1) similarly for the more clayey texture (25% < clay < 50%) with 63.27 ± 6 .1 g.a-1s-1. Rubber production from these new localities was generally good. So, through the results of this investigation, it should be noted that new rubber growing areas could be an asset for rubber production in Côte dIvoire. As a result, this culture can be encouraged in these areas, but with monitoring and supervision of producers on good agricultural practices.

Sigmoid models in the description of CO₂ evolved from legumes in the soil

The decomposition of legumes in the soil over time can be described by nonlinear sigmoid models. Thus, this study aimedto describe and to compare the fit of the nonlinear sigmoid models, Logistic and Gompertz, to the CO2 mineralization of fourlegume species over time in the soil, and indicate the most suitable model. Furthermore, it is also proposed to evaluate the CO2mineralization of legumes from two different edaphoclimatic conditions when added to the soil under controlled temperatureand humidity conditions. The following legume species used in green manure were evaluated: Arachis pintoi (forage peanut),Calopogonium mucunoides (calopo), Stylosanthes guianensis (Caribbean stylo), and Stizolobium aterrimum (mucuna). Arandomized block design with four replications was used. The soils from both areas are classified as Red-Yellow Latosol andhave a clayey texture. The mineralized carbon was measured at 48, 96, 144, 192, 240, 312, 384, and 480 hours fromthe beginning of incubation. Legumes in different locations had the same amount of potentially mineralizable carbon, andmicroorganisms had the same adaptation time to reach the maximum decomposition rate. The maximum decompositionrate occurs at the beginning of mineralization, and therefore the Gompertz model was more suitable than the Logistic modelin describing the decomposition of the four legumes in the soil.

Agronomic performance of green corn at different sowing times and nitrogen doses

The present study aimed to identify the best sowing time and the best nitrogen dose in topdressing of the corn crop for "green ear" consumption. The experiment was conducted between October 2018 and June 2019 in a commercial crop, in Ipameri, Goiás, Brazil. The soil in the experimental area is classified as dystrophic Red-Yellow Latosol with clayey texture. The experimental design used was the randomized blocks, in a 5 x 5 factorial scheme, with five sowing times [1st (10/19/2018); 2nd (11/29/2018); 3rd (01/08/2019); 4th (02/18/2019) and 5th (03/28/2019)], implemented with 40 days intervals, after the first sowing, and five nitrogen doses (0, 50, 100, 150, and 200 kg ha-1), with four replicates. The following factors were evaluated for each sowing time: relative chlorophyll index, leaf dry mass, leaf nitrogen content, plant height, first ear insertion height, ears diameter and length, the total yield of ears with husks, the yield of commercial ears without husks and grain yield. The data were submitted to the analysis of variance (F-test). The sowing times and nitrogen doses in topdressing influenced the leaf nitrogen content, relative chlorophyll index, leaf dry mass, yield, and most of its components. Thus, it can be indicated that the best time for sowing corn for fresh consumption is in October (1st sowing time), and the estimated nitrogen dose in topdressing to obtain the maximum yield is 160 kg ha-1 of nitrogen.

CULTIVARES DE SOJA AVALIADAS NO VALE DO PARANAPANEMA, SAFRA 2022/2023

The agronomic evaluation of different soybean cultivars was carried out in the municipalities of Assis and Palmital, located at Vale Paulista do Médio Paranapanema, São Paulo State, in the 2022/2023 season, in two sowing moment. The experimental design was completely randomized blocks, with 20 cultivars and 4 replicates per trial, and the means were grouped by the Scott-Knott test at 5% probability. The characteristics evaluated were: plant height (PH), height of insertion of the first pod (HIFP) and grain yield (GY). It was found that there is difference in GY, PH and HIFP among the cultivars evaluated in different environments. Most cultivars studied are agronomically suitable for cultivation in the Vale Paulista do Médio Paranapanema, with advantages for the genotypes indicated by positive interactions with the sites, and may favor the gains to farmers. The cultivars DM 66i68 and AS 3707 showed wider adaptability, with higher GY averages in the 4 evaluated environments, being option of planting in these environments. Considering also the GY, the cultivars CZ 37B43, CZ 37B51 and B 5710 emerge as options for cultivation in soils of more sandy texture while the cultivars ST 2607 and CZ Potent are options for cultivation in places whose soils are clayey texture. The observed GY were higher in October sowings in both sites. Keywords: Agronomic evaluation. Glycine max. Grain yield.

Power performance of a tractor-seeder-fertilizer system as a function of furrower depth in no-till

The negative effect of the traffic of machinery and agricultural implements associated with little soil disturbance promotes an increase in the density and resistance of the soil to penetration. An alternative to minimize the degree of soil compaction is to increase its mobilization in the seeding row utilizing the depth of action of the shank. The effect of plowing depth on the performance and energy requirement of a tractor-seeder-fertilizer combination was analyzed using a completely randomized design. The agricultural soil was an Oxisol with a clayey texture, submitted to soybean and corn cultivation in a no-till crop succession system. Using a shank at a greater cutting depth causes an increase in tractive effort, power demand, fuel consumption and slip, and reduces tractive efficiency.

Lime and gypsum application to low-acidity soils: Changes in soil chemical properties, residual lime content and crop agronomic performance

Crop yield gains and improvements in surface and subsurface soil chemical properties are evident when agricultural lime and gypsum are used in high-acidity soils. However, there is scarce information on the effects of lime and gypsum application on no-till tropical soils previously treated with these additives (low-acidity soils). The duration of the effects of lime applied to the soil surface varies according to lime rate, product characteristics, soil conditions, and water and thermal regimes. Such residual effects influence the timing of lime reapplication. This study aimed to investigate the effects of surface application of agricultural lime and gypsum on soil chemical properties, soybean and second-crop corn yields, and lime residual contents. The experiment was conducted on a Red Latosol with a very clayey texture in Floresta, Paraná, Brazil. Four rates of dolomitic lime (0.0, 2.6, 5.4, and 8.1 Mg ha−1) and agricultural gypsum (0, 4, 8, and 12 Mg ha−1) were used. The experimental design was a randomized complete block with subplots and four replications. The experiment lasted for four soybean seasons and three second-crop corn seasons. At 6, 12, 24, and 36 months after treatment, soil samples were collected from the 0.00–0.05, 0.05–0.10, 0.10–0.20, 0.20–0.30, 0.30–0.40, and 0.40–0.60 m layers for chemical analysis. No significant interaction effects were observed on soil chemical properties. Liming resulted in soil alkalization, with a consequent reduction in Al3+ and an increase in Ca, Mg, base saturation, and pH. Residual lime was not detected in layers deeper than 0.05 m, suggesting a lack of physical movement of particles in the soil pore space. Residual lime was detected on surface soil (0.00–0.05 m) up to 36 months after application, demonstrating the low reactivity of lime on no-till soils. At 6 months after gypsum application, there was an increase in Ca2+ levels up to the 0.6 m layer, whereas Mg2+ levels were reduced throughout the soil profile for up to 36 months. In no-till soybean–second-crop corn rotation systems, use of agricultural gypsum alone did not provide consistent effects on crop yield and reduced foliar Mg contents. Under the studied conditions of low acidity, liming did not produce significant differences in crop yield but improved soil chemical properties for plant growth under no-till.

Grain Yield of Maize Crops under Nitrogen Fertigation Using Wastewater from Swine and Fish Farming

Maize is one of the most important cereals in the world. It is a crop demanding in nitrogen. Therefore, alternative sources of fertilization bring agronomic, environmental and economic benefits. The objective of this study was to evaluate the biomass and productivity of maize fertigated with wastewater from swine and fish farming in different dilutions. The soil used is classified as Dystroferric Red Latosol, Cerrado phase, with clayey texture. The experimental design used was randomized blocks in 2 × 4 split plots with three replications. The treatments consisted of two sources of wastewater (fish farming and swine farming) diluted with the recommended dose of wastewater + 0, 25, 50 and 75% of its volume in water. The accumulation of dry mass (leaf, stalk and aerial parts) was evaluated at 30, 60, 90 and 110 days after sowing. The evaluation of yield variables (number of grain rows, number of grains per row, grain sizes, grain dry weight, gran yield and harvest index) occurred at 130 days after sowing. The largest accumulation of dry biomass at the end of the maize cycle and evaluated productivity variables were obtained with the application of swine farming wastewater. Wastewater from fish farming applied via an irrigation system without dilution (0%) is the most suitable for obtaining the productivity of corn grains. The two sources of wastewater have the potential to partially replace mineral nitrogen fertilizer in maize.

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.