Inoculation with Plant Growth-Promoting Bacteria and Nitrogen Doses Improves Wheat Productivity and Nitrogen Use Efficiency

Wheat is one of the staple foods of the global population due to its adaptability to a wide range of environments. Nitrogen is one of the crucial limiting factors in wheat production and is considered a challenge to food security. Therefore, sustainable agricultural technologies such as seed inoculation with plant growth-promoting bacteria (PGPBs) can be adopted to promote biological nitrogen fixation (BNF) for higher crop productivity. In this context, the objective of the current study was to evaluate the effects of nitrogen fertilization and seed inoculations with Azospirillum brasilense, Bacillus subtilis and A. brasilense + B. subtilis on agronomic and yield attributes, grain yield, grain N accumulation, N use efficiency and applied N recovery in Brazilian Cerrado, which consists of gramineous woody savanna. The experiment was carried out in two cropping seasons in Rhodic Haplustox soil under a no-tillage system. The experiment was designed in a randomized complete block in a 4 × 5 factorial scheme, with four replications. The treatments consisted of four seed inoculations (control-without inoculation, inoculation with A. brasilense, B. subtilis and A. brasilense + B. subtilis) under five N doses (0, 40, 80, 120 and 160 kg ha^-1, applied from urea) at the wheat tillering stage. Seed co-inoculation with A. brasilense + B. subtilis increased grain N accumulation, number of spikes m^-1, grains spike^-1 and grain yield of wheat in an irrigated no-tillage system of tropical savannah, regardless of the applied N doses. Nitrogen fertilization at a dose of 80 kg ha^-1 significantly increased grain N accumulation and number of grains spikes^-1 and nitrogen use efficiency. Recovery of applied N was increased with inoculation of B. subtilis and co-inoculation of A. brasilense + B. subtilis at increasing N doses. Therefore, N fertilization can be reduced by the inclusion of co-inoculation with A. brasilense + B. subtilis in the cultivation of winter wheat under a no-tillage system of Brazilian Cerrado.

Co-Inoculation with Azospirillum brasilense and Bradyrhizobium sp. Enhances Nitrogen Uptake and Yield in Field-Grown Cowpea and Did Not Change N-Fertilizer Recovery

This study was designed to investigate the effects of Azospirillum brasilense and Bradyrhizobium sp. co-inoculation coupled with N application on soil N levels and N in plants (total N, nitrate N-NO₃⁻ and ammonium N-NH₄⁺), photosynthetic pigments, cowpea plant biomass and grain yield. An isotopic technique was employed to evaluate ¹⁵N fertilizer recovery and derivation. Field trials involved two inoculations—(i) single Bradyrhizobium sp. and (ii) Bradyrhizobium sp. + A. brasilense co-inoculation—and four N fertilizer rates (0, 20, 40 and 80 kg ha⁻¹). The co-inoculation of Bradyrhizobium sp. + A. brasilense increased cowpea N uptake (an increase from 10 to 14%) and grain yield (an average increase of 8%) compared to the standard inoculation with Bradyrhizobium sp. specifically derived from soil and other sources without affecting ¹⁵N fertilizer recovery. There is no need for the supplementation of N via mineral fertilizers when A. brasilense co-inoculation is performed in a cowpea crop. However, even in the case of an NPK basal fertilization, applied N rates should remain below 20 kg N ha⁻¹ when co-inoculation with Bradyrhizobium sp. and A. brasilense is performed.

Silicon Amendment Enhances Agronomic Efficiency of Nitrogen Fertilization in Maize and Wheat Crops under Tropical Conditions

Sustainable management strategies are needed to improve agronomic efficiency and cereal yield production under harsh abiotic climatic conditions such as in tropical Savannah. Under these environments, field-grown crops are usually exposed to drought and high temperature conditions. Silicon (Si) application could be a useful and sustainable strategy to enhance agronomic N use efficiency, leading to better cereal development. This study was developed to explore the effect of Si application as a soil amendment source (Ca and Mg silicate) associated with N levels applied in a side-dressing (control, low, medium and high N levels) on maize and wheat development, N uptake, agronomic efficiency and grain yield. The field experiments were carried out during four cropping seasons, using two soil amendment sources (Ca and Mg silicate and dolomitic limestone) and four N levels (0, 50, 100 and 200 kg N ha⁻¹). The following evaluations were performed in maize and wheat crops: the shoots and roots biomass, total N, N-NO₃⁻, N-NH₄⁺ and Si accumulation in the shoots, roots and grain tissue, leaf chlorophyll index, grain yield and agronomic efficiency. The silicon amendment application enhanced leaf chlorophyll index, agronomic efficiency and N-uptake in maize and wheat plants, benefiting shoots and roots development and leading to a higher grain yield (an increase of 5.2 and 7.6%, respectively). It would be possible to reduce N fertilization in maize from 185–180 to 100 kg N ha⁻¹ while maintaining similar grain yield with Si application. Additionally, Si application would reduce N fertilization in wheat from 195–200 to 100 kg N ha⁻¹. Silicon application could be a key technology for improving plant-soil N-management, especially in Si accumulator crops, leading to a more sustainable cereal production under tropical conditions.

Inoculation With Growth-Promoting Bacteria Azospirillum brasilense and Its Effects on Productivity and Nutritional Accumulation of Wheat Cultivars

Agricultural practices that allow a productive increase in a sustainable manner are becoming increasingly necessary to feed an ever-growing global population. The inoculation with Azospirillum brasilense has the potential to reduce the use of synthetic mineral fertilizers with efficient capacity to promote plant growth and increase nutrition. Therefore, this research was developed to investigate the potential use of A. brasilense to increase the accumulation of macro- and micronutrients and its influence on grain yield, plant height, and spike population in two wheat cultivars (CD1104 and CD150), under irrigated conditions in the Brazilian Cerrado. The study was carried out in a Rhodic Hapludox under a no-tillage system. The experiment was designed in randomized blocks with six replications, arranged in a 2 × 2 factorial scheme: two cultivars (CD150 and CD1104) and two levels of inoculation (control and with A. brasilense). The inoculation with A. brasilense provided greater accumulation of micronutrients in the aerial part of the wheat. In the cultivar CD1104, B and Cu had an accumulation 27.7 and 57.4% higher compared with those of the control without bacteria. In the cultivar CD150, Azospirillum increased the accumulation of B, Fe, and Mn by 43.8, 49.9, and 22%, respectively, and reduced Cu by 21.9%, compared with those of the control. The cultivar CD150 has greater efficiency to accumulate N (+35.5 kg N ha−1) as compared with the cultivar CD1104. Interactions between inoculation and cultivars resulted in greater accumulation of S and K in the shoot of the wheat cultivar CD150, as well greater accumulation of Cu in CD1104. In growth assessments, inoculation or cultivars did not statistically influence wheat grain yield and spike population. Howevere, for plant height, the CD1104 genotype has 13.1% bigger plant height on average than that of the CD150 genotype. Inoculation can contribute more sustainably to wheat nutrition.

Technical and economic viability of cowpea co-inoculated with Azospirillum brasilense and Bradyrhizobium spp. and nitrogen doses

ABSTRACT Biological nitrogen fixation efficiency can be increased by co-inoculation with Bradyrhizobium spp. and Azospirillum brasilense, allowing even greater uptake of water and nutrients, leading to higher yields and enabling the insertion of unusual crops, such as cowpea (Vigna unguiculata L. Walp.), in the agricultural production system in the Cerrado region of Brazil. Thus, this study aimed to evaluate the technical and economic viability of cowpea in the Cerrado region, as a function of N doses and co-inoculation of seeds with Azospirillum brasilense and Bradyrhizobium. The study was carried out in a no-tillage system in Selvíria, MS, Brazil. The experimental design was a randomized block design, with four repetitions, arranged in a 3 x 5 factorial scheme, corresponding to three types of inoculation (without inoculation - control, with two strains of Bradyrhizobium spp. SEMIA 6462 and SEMIA 6463 - the conventional inoculation of cowpea, and these two strains of Bradyrhizobium spp. plus A. brasilense strains Ab-V5 and Ab-V6); and five N doses (0, 20, 40, 80 and 160 kg ha-1), as urea, applied as topdressing. The following evaluations were performed: grain yield, total operating cost, effective operating cost, gross revenue, operating profit, profitability index, equilibrium price and equilibrium yield. Co-inoculation with A. brasilense increases cowpea grain yield, which makes cowpea production in the Cerrado region of Brazil technically and economically viable, without the need to apply N fertilizers in topdressing.

Influence of Azospirillum brasilense associated with silicon and nitrogen fertilization on macronutrient contents in corn

Information regarding the interaction between biological nitrogen fixation (BNF) with Azospirillum brasilense inoculation and the use of silicon (Si) is needed. Silicon exerts numerous benefits on grasses, especially when the plants are subjected to biotic and abiotic stresses, affecting plant nutrition. The aim of this research was to determine if there is a synergistic effect between the inoculation with A. brasilense and Si use, on macro-nutrient content in corn shoot and root. The field trial was performed in Selvíria, Brazil, on a Typic Rhodic Hapludox soil under no-till system. The experimental design was a completely randomized block design with four replicates arranged in a 2 × 5 × 2 triple factorial arrangement, consisting of two soil acidity corrective sources (dolomitic limestone and Ca and Mg silicate as sources of Si); five N doses (0, 50, 100, 150 and 200 kg ha-1 applied in topdressing); with and without seed inoculation with A. brasilense. The inoculation favored N concentration in shoots and increased the N and S concentration even when associated to high N rates in topdressing. The Si as Ca and Mg silicate associated with the increment of N rates does not promote an increase in the macronutrients uptake. Although it did not favor the N use, the Si also did not negatively affect the benefits of the A. brasilense.

Inoculation of Azospirillum brasilense associated with silicon as a liming source to improve nitrogen fertilization in wheat crops

This research was developed to investigate whether inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in wheat and to evaluate and correlate nutritional and productive components and wheat grain yield. The study was carried out on a Rhodic Hapludox under a no-till system with a completely randomized block design with four replications in a 2 × 2 × 5 factorial scheme: two liming sources (with Ca and Mg silicate as the Si source and limestone); two inoculations (control - without inoculation and seed inoculation with A. brasilense) and five side-dress N rates (0, 50, 100, 150 and 200 kg ha-1). The results of this study showed positive improvements in wheat growth production parameters, NUE and grain yield as a function of inoculation associated with N rates. Inoculation can complement and optimize N fertilization, even with high N application rates. The potential benefits of Si use were less evident; however, the use of Si can favour N absorption, even when associated with A. brasilense. Therefore, studies conducted under tropical conditions with Ca and Mg silicate are necessary to better understand the role of Si applied alone or in combination with growth-promoting bacteria such as A. brasilense.

Can silicon applied to correct soil acidity in combination with Azospirillum brasilense inoculation improve nitrogen use efficiency in maize?

Alternative management practices are needed to minimize the need for chemical fertilizer use in non-leguminous cropping systems. The use of biological agents that can fix atmospheric N has shown potential to improve nutrient availability in grass crops. This research was developed to investigate if inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in maize. The study was set up in a Rhodic Hapludox under a no-till system, in a completely randomized block design with four replicates. Treatments were tested in a full factorial design and included: i) five side dress N rates (0 to 200 kg ha-1); ii) two liming sources (Ca and Mg silicate and dolomitic limestone); and iii) with and without seed inoculation with A. brasilense. Inoculation with A. brasilense was found to increase grain yield by 15% when N was omitted and up to 10% when N was applied. Inoculation also increased N accumulation in plant tissue. Inoculation and limestone application were found to increase leaf chlorophyll index, number of grains per ear, harvest index, and NUE. Inoculation increased harvest index and NUE by 9.5 and 19.3%, respectively, compared with non-inoculated plots. Silicon application increased leaf chlorophyll index and N-leaf concentration. The combination of Si and inoculation provided greater Si-shoot accumulation. This study showed positive improvements in maize growth production parameters as a result of inoculation, but the potential benefits of Si use were less evident. Further research should be conducted under growing conditions that provide some level of biotic or abiotic stress to study the true potential of Si application.

Nitrogen fertilization and glyphosate doses as growth regulators in Esmeralda grass

ABSTRACT Despite maintaining the green color in turfgrasses, nitrogen (N) fertilization affects shoot growth and, consequently, the frequency of cuts, the main factor in the costs of turfgrass maintenance. Therefore, this study aimed to evaluate N fertilization and the use of glyphosate as a growth regulator in Esmeralda grass (Zoysia japonica Steud.). The experiment was conducted in the field, from August 2014 to July 2015, using a randomized block design in a 5 x 4 factorial scheme with four repetitions and 20 treatments, namely: control (without N), 15 g m-2 of N in soil without foliar N; 30 g m-2 of N in soil without foliar N; 15 g m-2 of N in soil with foliar N (1% urea in 200 L ha-1) and 30 g m-2 of N in soil with foliar N combined with glyphosate doses (0, 200, 400 and 600 g ha-1 active ingredient (a.i.)). The N doses were split into five applications along the year. The following variables were evaluated: height, leaf chlorophyll index and foliar accumulation of nitrogen, phosphorus and potassium. Fertilization with 15 g m-2 of N in soil without foliar N application, split into five times along the year, was adequate for the turfgrass, while foliar fertilization did not promote benefits. The glyphosate dose of 400 g ha-1 a.i. was effective in reducing the growth of Esmeralda grass, without compromising its color and promoted less N, P and K accumulation in the leaves, reducing the height and dry matter production.

Nutritional assessment and yield of corn as a function of boron rates and zinc fertilization

Brazilian Cerrado soils are commonly deficient in boron (B) and zinc (Zn). It is still debated whether B and Zn interaction has a synergistic or antagonistic effect on the absorption thereof. Thus, we conducted this study to evaluate the effect of boron rates (0, 1, 2, 3, and 4 kg ha?1, as boric acid), with or without zinc fertilization (2 kg ha?1 Zn, as zinc sulfate), on corn nutritional status and grain yield. We also assessed the residual effect of such fertilization on the fall corn crop grown on an Oxisol in a no-tillage system. A synergistic effect between B and Zn was observed on corn nutritional status when applied to the soil at rates of up to 2 kg ha?1, with higher soil contents resulting from the interaction between these micronutrients. Zinc fertilization and increasing boron rates had no significant influence on corn grain yield in both spring/summer and fall crops, grown on a boron-deficient, clayey soil of Cerrado biome.

CRESCIMENTO INICIAL DE CLONES DE EUCALYPTUS EM FUNÇÃO DA ADUBAÇÃO DE NPK

A adubação NPK e a escolha do material genético são fundamentais no estabelecimento e na produtividade da cultura. Assim objetivou-se avaliar o efeito de adubação mineral de plantio, no crescimento de clones de eucalipto (Eucalyptus urophylla x Eucalyptus grandis), em solo de Cerrado. O experimento foi conduzido de outubro de 2015 a julho de 2017, na fazenda Campo Verde IV, localizada no município de Selvíria - MS. O delineamento experimental foi o de blocos casualizados com 12 tratamentos e quatro repetições, em esquema fatorial 3x4, sendo três clones (I144, H13 e 1528) e quatro doses: 0, 160, 320 e 640 kg ha-1 da fórmula 08-32-16 + 0,5% B, 0,5% Cu e 0,5% Zn. Cada parcela foi composta por 42 plantas, distribuídas em sete linhas de seis plantas cada, totalizando 378,0 m2 de área, sendo considerada área útil apenas as seis plantas centrais, totalizando 54,0 m2. Foram avaliados aos 17 meses de idade o diâmetro à altura do peito (DAP) e volume de madeira com casca. A adubação propiciou aumento do DAP e da produtividade de madeira para os três clones, sendo o 1528 mais produtivo.

Nitrogen rates associated with the inoculation of Azospirillum brasilense and application of Si: Effects on micronutrients and silicon concentration in irrigated corn

The aim of this study was to analyze whether there are differences between the inoculation with Azospirillum brasilense and the silicon application, thus enabling a higher efficiency of nitrogen fertilization, evaluating micronutrients and silicon concentration in shoots and roots of irrigated corn (Zea mays). The experiment was conducted in Selviria, Brazil, under a no-till system, on a Typic Rhodic Hapludox. The experiment was set up as a randomized block design with four replications, in a 2 × 5 × 2 factorial arrangement consisting of two soil corrective sources (dolomitic limestone and Ca and Mg silicate as source of Si); five N rates (0, 50, 100, 150 and 200 kg ha-1); with and without inoculation with A. brasilense. N rates increased B, Cu and Fe concentrations in shoots and B, Cu, Fe, Mn, Zn and Si in roots. Inoculation provided greater concentrations of B and Fe in shoots, and B in roots. Although inoculation with A. brasilense favored micronutrient uptake, it negatively affected Si concentration in shoots in 2015/16 crop. The use of Si in the form of Ca and Mg silicate promotes an increase in Mn, Si and Zn uptake in shoots and Mn and Si concentration in roots.

Do the application forms and doses of boron affect wheat crops?

ABSTRACT Boron is one of the most limiting micronutrients in the grain production system in Brazil. Thus, the objective of this study was to evaluate the effects of the application forms and doses of boron on the concentration of this nutrient in the leaves, straw, and grains of wheat, as well as the production components and grain yield. The residual effect of boron in the soil was also evaluated. An experiment was conducted in a no-tillage system in Oxisol with clay texture in Selvíria, Mato Grosso do Sul. The experimental design was a randomized block design with four replicates arranged in a 4 x 3 factorial scheme. Four doses of boron (0, 1, 2, and 4 kg ha-1) were applied with a boric acid source (B = 17%) and three application forms: a) during the desiccation of the predecessor straw with herbicide; b) at the time of sowing in soil along with formulated fertilization seeding, and c) via the leaves with the application of post-emergent herbicide. The application of boron to the soil at the time of sowing at an approximate dose of 2 kg ha-1 provides the highest number of spikelets per ear and wheat grain yield.

Doses and forms of Azospirillum brasilense inoculation on maize crop

ABSTRACT In search of a more sustainable agriculture, the use of beneficial microorganisms has been highlighted, because they are low-cost and can reduce the use of fertilizers and increase grain yield. The present study aimed to evaluate the efficiency of A. brasilense inoculation and the best form and dose of inoculation in maize, measuring the impact on some physical characteristics and on its nutrition. The experiment was conducted in a greenhouse, in Ilha Solteira, SP, Brazil, in a completely randomized design, with four replicates and eight treatments: 1) control; 2) Seed 1x; 3) Seed 2x; 4) Soil 1x; 5) Soil 2x; 6) Leaf 1x; 7) Leaf 2x; 8) Seed 1x + Leaf 1x, respectively representing in each treatment the site and dose of application (1x, dose recommended by the manufacturer; 2x, twice the dose recommended by the manufacturer). No differences were found in any physical characteristics evaluated between treatments; however, for nutrient contents in the leaf tissue, there was effect on Zn content. It was concluded that, regardless of the presence of A. brasilense inoculation, forms or dose (in hybrid DKB 350), in general, there were no improvements in the characteristics evaluated.

Effect of phosphorus applied as monoammonium phosphate-coated polymers in corn culture under no-tillage system

The use of phosphate fertilizers as coated polymers reduces phosphorus losses that occur by adsorption of P to soil particles, thereby providing this essential nutrient for a longer period. The objective of this study was to evaluate the effect of phosphorus doses applied as conventional monoammonium phosphate or as coated polymers on corn grown in a clayey Oxisol, in the Cerrado region. The experiment was conducted in Selvíria - MS, located at 22°22? S and 51°22? W. The experiment was laid out in a randomized block design arranged as a 4 × 2 factorial, with four doses of P2O5 (0, 50, 100, and 150 kg ha-1) and two sources of phosphorus (monoammonium phosphate (MAP) and monoammonium phosphate coated polymers). The experiment was conducted under no-tillage system during the cropping seasons in 2008/09 and 2009/10. The MAP and MAP-coated sources did not differ in most of the yield components in either of the two seasons. We found a quadratic function adjustment for P doses up to 117 and 98 kg ha-1 of P2O5 for P concentration in leaf tissue and grain yield in the 2008/2009 crop, respectively. We also obtained a quadratic function adjustment for P rates for grain yield and number of plants, up to 118 and 113 kg ha-1 of P2O5, respectively, in the 2009/2010 harvest.

Wheat yield in the Cerrado as affected by nitrogen fertilization and inoculation with Azospirillum brasilense

Abstract: The objective of this work was to evaluate the effect of inoculation with Azospirillum brasilense, associated with N rates and sources, in soil of the Cerrado (Brazilian savanna), on the grain yield of irrigated wheat (Triticum aestivum). The experiment was carried out under a no-tillage system in a Typic Haplustox. The experimental design was randomized complete blocks with four replicates, in a 2x5x2 factorial arrangement: two N sources (urea and urea with NBPT urease inhibitor); five N rates applied as topdressing (0, 50, 100, 150, and 200 kg ha-1); and with or without seed inoculation with A.brasilense. The increase in the N rates positively affected spike length, number of spikelets and of grains per spike, number of spikes per meter, N accumulation in the straw, leaf chlorophyll content, and grain yield of irrigated wheat, regardless of the use of NBPT urease inhibitor with conventional urea. Singly, inoculation with A.brasilense does not affect production components and grain yield, despite the increase in N content in wheat straw. The inoculation with A.brasilense, associated with the application of 140 kg ha-1 N, provides the highest grain yield of irrigated wheat cropped after corn in low-altitude Cerrado.

Economic analysis of corn inoculated with Azospirillum brasilense associated with nitrogen sources and doses

Azospirillum brasilense is a bacterium known for its biological nitrogen fixation (BNF) in corn crops. However, there is a lack of comprehensive research defining how much mineral N should be applied to maximize the efficiency of BNF and attain high, economically sustainable yields. Moreover, it would be interesting to investigate whether adding urea with NBPT urease inhibitor might increase BNF in grasses. Therefore, the aim of this study was to determine the effect of inoculation with Azospirillum brasilense associated with N sources and doses in a Cerrado biome soil by evaluating the grain yield of irrigated corn in economic terms. The experiment was conducted in Selvíria, MS, Brazil under a no-till system on a Latossolo Vermelho distrófico (Oxisol). The experiment was set up as a randomized block design with four replications in a 2 × 5 × 2 factorial arrangement consisting of two sources of N (urea and urea with NBPT urease enzyme inhibitor) and five N doses applied as top-dressing (0, 50, 100, 150, and 200 kg ha-1), with and without the inoculation of seeds with A. brasilense. Inoculation with Azospirillum brasilense makes corn growth much more profitable, irrespective of the dose and source of N. Addition of 200 kg ha-1 N in the form of conventional urea coupled with inoculation with Azospirillum brasilense increases grain yield; however, the highest economic return is obtained with N applied at 100 kg ha-1 with conventional urea and inoculation.

Chemical soil attributes after wheat cropping under nitrogen fertilization and inoculation with Azospirillum brasilense

Azospirillum brasilense plays an important role in biological nitrogen fixation (BNF) in grasses. However, further studies are needed to define how much mineral N can be applied while simultaneously maintaining BNF contribution and maximizing crop yield and to determine the impact of these practices on soil fertility. Thus, we aimed to investigate the effect of inoculation with A. brasilense, in conjunction with varying N doses and sources in a Cerrado soil, on soil chemical attributes after two years of irrigated wheat production. The experiment was initiated in Selvíria - MS under no-tillage production in an Oxisol in 2014 and 2015. The experimental design was a randomized block design with four replications, and treatments were arranged in a 2 x 5 x 2 factorial arrangement as follows: two N sources (urea and Super N - urea with inhibitor of the enzyme urease NBPT (N - (n-butyl thiophosphoric triamide))), five N rates (0, 50, 100, 150 and 200 kg ha-1), and with or without seed inoculation with A. brasilense. The increase in N rates did not influence the chemical soil attributes. Super N acidified the soil more compared to urea. A. brasilense inoculation reduced the effect of soil acidification in intensive irrigated wheat cultivation; however, the base extraction was higher, resulting in a lower soil CEC after cultivation with inoculation. Therefore, the cultivation of wheat inoculated with A. brasilense was not harmful to soil fertility because it did not reduce the base saturation and organic matter content (P, K, Ca, Mg, and S).

ADUBAÇÃO NITROGENADA NA IMPLANTAÇÃO DE Urochloa brizantha cv. XARAÉS NO CERRADO: Características Biométricas e Bromatológicas - Parte 1

A adubação tem proporcionado grandes avanços na produtividade e qualidade de pastagens, e entre os nutrientes, o nitrogênio (N) merece destaque por sua grande extração e aumento da produtividade das pastagens, porém, após sua aplicação ao solo, sofre influência do meio e pode ser perdido, quando mal manejado. Para minimizar tal problema, uma alternativa promissora é o uso de fertilizantes de eficiência aumentada, buscando-se reduzir tais perdas e proporcionar aumento de produtividade. Dessa forma, avaliou-se o efeito de fontes e doses de N na implantação de Urochloa brizantha cv. Xaraés (capim-xaraés) na produtividade e nos valores bromatológicos, em cultivo em condições do Cerrado. O experimento foi conduzido em área experimental no município de Rio Verde - GO, distribuídos em blocos ao acaso com quatro repetições, em esquema fatorial de 3x4. O primeiro fator foram três fontes de N (ureia convencional, ureia de eficiência aumentada e nitrato de amônio); o segundo fator foram quatro doses de N (0, 20, 40 e 80 kg N ha-1 corte-1). O uso da ureia convencional fez-se como a melhor alternativa para a cultura do capim-xaraés (P ≥ 0,05). A dose de nitrogênio recomendada é de 80 kg ha-1 por corte (P < 0,05), em vista do aumento da produtividade de massa seca, e à melhoria da qualidade bromatológica do capim-xaraés.

ADUBAÇÃO NITROGENADA NA IMPLANTAÇÃO DE Urochloa brizantha cv. XARAÉS NO CERRADO: Características nutricionais - Parte 2

Entre os fatores agrícolas, a adubação tem proporcionado grandes avanços na produtividade e qualidade de pastagens, sendo que o nitrogênio (N) merece destaque por sua grande extração e aumento da produtividade de gramíneas, entretanto, sofre influência do meio e pode ser perdido se mal manejado. Para minimizar tal problema, uma alternativa apontada como promissora é o uso de fertilizantes de eficiência aumentada. Dessa forma, objetivou-se com o trabalho avaliar o efeito de fontes e doses de N na implantação do Urochloa brizantha cv. Xaraés (capim-xaraés), em cultivo nas condições do Cerrado. O experimento foi conduzido em área experimental no município de Rio Verde – GO, Brasil, com delineamento em blocos ao acaso com quatro repetições, em esquema fatorial de 3x4. Sendo três fontes de N (ureia convencional, ureia de eficiência aumentada e nitrato de amônio); e quatro doses de N (0, 20, 40 e 80 kg N ha-1 corte-1). O uso da ureia convencional fez-se como a melhor alternativa para a cultura do capim-xaraés, a ureia revestida não foi considerada de maior eficiência. A dose de nitrogênio recomendada é de 80 kg ha-1 por corte, em vista da melhoria nutricional da matéria seca da parte aérea.

Nitrogen dose and type of herbicide used for growth regulation on the green coloration intensity of Emerald grass

ABSTRACT: Nitrogen (N) is the main nutrient responsible for the green coloration of lawns but also stimulates the growth of the aerial portion of grass, thus increasing mowing expenses. Therefore, herbicides may be used as a growth regulator. The ideal herbicide will reduce lawn height without affecting esthetics. Toward this end, the aim of the present study was to evaluate the green coloration of Emerald grass ( Zoysia japonica Steud.) under the effect of different N doses or herbicides used as growth regulators. The study site consisted of randomized blocks containing 20 treatments arranged in a 5×4 factorial design with four treatment groups: four herbicides (glyphosate, imazaquin, imazethapyr, and metsulfuron-methyl, accounting for 200, 420, 80, and 140g ha-1 of the active ingredient, respectively) and the control sample (no herbicide); and three doses of N in the form of urea (5, 10, and 20g m-2), divided into five applications per year, in addition to a treatment without N. Leaf chlorophyll content (LCC) was assessed and the aerial portion of the lawn was measured with digital image analysis. Doses of N ranging from 10 to 20g m-2, divided into five applications a year, provided the lawn with intense green coloration, and the herbicides glyphosate (200g ha-1), imazaquin (420g ha-1), and imazethapyr (80g ha-1) were reported to be suitable for use as growth regulators of the study species, considering maintenance of esthetic quality (green coloration). The digital image analysis of the aerial portion provided more accurate results than use of a chlorophyll meter with regard to the recommendation of both N dose and herbicides to be used as growth regulators of Emerald grass.

Sources and application methods of boron in Eucalyptus crop

Cerrado soils have low boron (B) content, making supplementation of this element through fertilization via soil and/or leaf is a common practice. It is therefore important to establish the best mode of application and source of B for the proper development of eucalyptus. Thus, the objective of this study was to compare the effect of B sources with high and low solubility on eucalyptus cultivation and to examine the effect of foliar application of the micronutrient. The experiment was conducted in an area located at 20o 34’ S latitude and 51o 50’ W longitude with an altitude of 305 m during the period from January 2012 to February 2014. The experiment was set up using a randomised complete block design with six treatments and five replications, in a 3 x 2 factorial scheme, consisting of 0 kg ha-1 of B, 1 kg ha-1 of B using boric acid as a source (high solubility, 17% B) or 1 kg ha-1 of B using borogran as a source (low solubility, 10% B), applied to the planting furrow, with or without foliar application of 0.5% boric acid in a solution with a volume of 250 L ha-1. Except for the case of foliar B application, there was an increase in plant height in treatments that received the micronutrient at planting, which differed significantly from the control. However, both sources, independent of solubility, exhibited similar results. The two foliar B applications were sufficient to cause an increase in plant height when compared to treatments without B application at planting, at 21 months. At 24 months after planting, an increase in leaf B was observed in treatments with foliar application. However, this did not improve growth, diameter at breast height (DBH) or timber volume of the eucalyptus clone. Both the application of B at planting (independent of the source used) and the foliar application of the element were sufficient to reduce the symptoms of B deficiency. With respect to the sources used at planting, at a dose of 1 kg ha-1 of B, both sources produced similar results for plant height, DBH and timber volume.

Doses, fontes e épocas de aplicação de nitrogênio influenciando teores de clorofila e produtividade do trigo

Para obter altas produtividades de trigo, são necessários o manejo correto da adubação nitrogenada e a utilização de cultivares de alto potencial produtivo. Sendo assim, objetivou-se avaliar doses e fontes de nitrogênio (N), aplicadas totalmente em semeadura ou em cobertura, na produção e nos seus componentes em dois cultivares de trigo irrigado, em sistema de plantio direto, cultivado numa região de cerrado de baixa altitude. O delineamento experimental foi em blocos ao acaso, em esquema fatorial 5 × 3 × 2 × 2, com três repetições, combinando cinco doses de N (0, 50, 100, 150 e 200 kg ha-1), três fontes de N (Entec®, sulfato de amônio e ureia), duas épocas de aplicação de N (na semeadura, ao lado das linhas, ou em cobertura), e em dois cultivares de trigo (IAC 370 e Embrapa 21). Os cultivares de trigo tiveram produtividade de grãos semelhantes. As fontes de N não diferiram para produtividade de grãos e demais avaliações. O N fornecido totalmente na semeadura não diferiu da aplicação tradicional, em semeadura e cobertura, para a produção do trigo irrigado em plantio direto. O incremento das doses de N aumentou os teores foliares de N e de clorofila, a altura de plantas e o número de espigas por m². A produtividade de grãos dos cultivares IAC 370 e Embrapa 21 aumentaram até as doses de 134 e 128 kg ha-1 de N, respectivamente, independentemente da época de aplicação e da fonte de N. A correlação positiva entre o teor de clorofila e a produtividade de grãos em razão das doses de N indicou que a adubação nitrogenada de cobertura pode ser recomendada a partir das leituras (SPAD) de clorofila realizadas aos 38 dias, após a emergência do trigo.

Decomposição da palhada de forrageiras em função da adubação nitrogenada após o consórcio com milho e produtividade da soja em sucessão

Objetivou-se neste trabalho avaliar a decomposição da palhada de Urochloa e Panicum após o consórcio com milho e adubação nitrogenada, assim como o desempenho agronômico da soja em sucessão. O experimento foi conduzido num Latossolo Vermelho distroférrico em condições de Cerrado, sob sistema de plantio direto. Após a colheita do milho consorciado com capim e corte de homogeneização das forrageiras, foram aplicadas doses de N (0, 50, 100 e 200 kg ha-1, fonte ureia) em cobertura. As parcelas foram constituídas por Urochloa brizantha cv. Xaraés, Urochloa ruziziensis, Panicum maximum cv. Tanzânia e Mombaça, semeadas na ocasião da semeadura do milho, e as subparcelas, compostas pela quantidade acumulada de nitrogênio aplicada nas plantas forrageiras anteriores ao cultivo da soja (0, 250, 500 e 1.000 kg ha-1 de N, após cinco cortes). O delineamento experimental foi de blocos casualizados, com quatro repetições, em esquema de parcelas subdivididas. Logo após o último corte das forrageiras, quantidade proporcional de massa fresca das espécies de cada subparcela foi acondicionada em sacos de nylon "Litter Bags", sendo eles depositados em contato direto com o solo, para determinação do tempo de decomposição da massa seca ao longo de 150 dias. As doses de N, assim como os consórcios de milho com forrageiras (exceto com Mombaça) interferem de forma semelhante na decomposição da palhada das forrageiras e na produtividade da soja em sucessão. Em todos os consórcios de milho e adubação nitrogenada antecessores aos 60 dias após a dessecação e corte, restavam ainda entre 50 e 60% da palhada inicial para SPD.

Adubação com KCl revestido na cultura do milho no Cerrado

A utilização de cloreto de potássio revestido pode proporcionar maior absorção deste elemento resultando na alteração dos teores foliares, dos componentes de produção e da produtividade. Neste contexto objetivou-se, com este trabalho, avaliar o efeito de doses de potássio usando cloreto de potássio convencional e revestido por polímeros, na cultura do milho em condições de Cerrado de baixa altitude. O experimento foi conduzido em Selvíria, MS, num Latossolo Vermelho distrófico de textura argilosa. Os tratamentos constaram de 4 doses de K2O (0, 40, 80 e 120 kg ha-1), aplicadas na semeadura, em duas fontes: KCl convencional e KCl revestido por polímeros. O delineamento estatístico utilizado foi o de blocos casualizados constando de 8 tratamentos e 4 repetições. O KCl revestido não foi eficiente visto que proporcionou resultados semelhantes ao KCl convencional para o teor foliar de K, componentes de produção e produtividade de grãos de milho. O incremento das doses de K2O influenciou positivamente os teores foliares de K e de clorofila, a altura da planta e de inserção da espiga e o número de fileiras e de grãos por espiga. A máxima produtividade de grãos de milho foi obtida com a aplicação de 83,5 kg ha-1 de K2O, em média.

Estimativa da produtividade de trigo em função da adubação nitrogenada utilizando modelagem neuro fuzzy

Atualmente, novas técnicas de processamento de dados, tais como redes neurais, lógica nebulosa (fuzzy) e sistemas híbridos, são utilizadas para elaborar modelos de predição em sistemas complexos e estimar parâmetros desejados. Neste artigo investigou-se a habilidade de se desenvolver um modelo de inferência adaptativo neuro fuzzy para estimação da produtividade de trigo utilizando-se uma base de dados da combinação dos seguintes tratamentos: cinco doses de N (0, 50, 100, 150 e 200 kg ha-1); três fontes (Entec, sulfato de amônio e ureia); duas épocas de aplicação de N (na semeadura ou em cobertura) e dois cultivares de trigo (E21 e IAC 370), avaliados durante dois anos, em Selvíria, MS. Através dos dados de entrada e saída o sistema de inferência neuro fuzzy adaptativo apreende e posteriormente pode estimar um novo valor de produção de trigo com base em doses diferenciadas de N. O erro de predição da produtividade de trigo em função das cinco doses de N, obtido com o sistema neuro fuzzy, foi menor que o valor obtido utilizando-se uma aproximação quadrática. Os resultados mostraram que o sistema neuro fuzzy é viável para desenvolver um modelo de predição visando estimar a produtividade de trigo em função da dose de N.