Influence of nitrogen fertilization and green manure on the economic feasibility of no-tilled wheat in the Cerrado

The search for higher profitability in wheat crop with cost reduction technologies that may promote sustainability is an important matter in Brazilian agriculture. This study evaluated the profitability of no-tilled wheat, reducing nitrogen topdressing doses with the cultivation of green manure before the wheat crop. The experiment was carried out in Selvíria (MS), Brazil, in 2009/10. The experiment was arranged in a randomized block design with 36 treatments in splitplots and four replicates. The plots were formed by six types of green manure: Cajanus cajan L. BRS Mandarin, Crotalaria juncea L., Pennisetum americanum L. BRS 1501, fallow area and mixed cropping of Pennisetum americanum L. + Cajanus cajan L. and Pennisetum americanum L. + crotalaria which provided straw for no-tilled wheat in the winter, following the rice crop in the summer. The subplots were formed by six levels of topdressing nitrogen (0, 25, 50, 75, 100 and 125 kg N ha-1) using urea as a nitrogen source. The wheat grown after green manure in the previous winter crop, with no nitrogen topdressing and a rate of 25 kg ha-1 N, had more frequently production costs above the gross income. Wheat production cost after the mixed cropping Pennisetum americanum L. + Cajanus cajan L. and Pennisetum americanum L. + Crotalaria juncea L. from the previous winter crop, combined with nitrogen rates of 50 and 75 kg N ha-1, provided better profitability compared with the other green manures evaluated.

Inoculation with Azospirillum, associated with nitrogen fertilization in maize

The biological nitrogen fixation is an alternative to supply the nitrogen needed for maize. The objective of this study was to evaluate the development and yield of maize in response to inoculation with Azospirillum associated with nitrogen fertilization. We conducted two field experiments in the summer harvest, the first in the 2000/2001 crop year in the region of Marechal Cândido Rondon, under conventional tillage, and second in the 2002/2003 agricultural year in the region of Cascavel, under no tillage. The experimental design in both experiments was a randomized complete block, with four replications, 2x2x2 factorial, with two levels of nitrogen at sowing (zero and 20 kg ha-1), two levels of inoculum (zero and 200 g ha-1) and two levels of nitrogen in topdressing (zero and 100 kg ha-1). There was evaluated the height of ear insertion, total plant height, leaf N content, shoot dry biomass and grain yield. The height of ear insertion and total plant height were not influenced by the factors under study. Nitrogen fertilization at sowing increased the leaf N content, causing the opposite effect when combined with inoculation. Inoculation with Azospirillum in the absence of nitrogen, provide productivity increases of 15.4% and 7.4% for 2000/2001 and 2002/2003 crops, respectively. The inoculation provided productivity similar to that obtained with 100 kg ha-1 in topdressing in crop 2000/2001, while in association with the topdressing, reduced productivity and shoot dry biomass in crop 2002/2003.

Spacing, population density and nitrogen fertilization in corn grown in an Oxisoil

The objective of this study was to evaluate yield components, leaf nitrogen content and grain yield in corn as affected by row spacing, plant density and nitrogen topdressing. The experiment was conducted with the single-cross hybrid AG 8021, in the municipality of Toledo-PR, in an Oxisoil under no-tillage system, in the crop year 2005/ 2006. The experiment was arranged in a randomized block design and treatments in split-split-plots, with four replications. The two row spacings (0.45 and 0.90 m) were allocated in the main plots, the two plant densities (60,000 and 80,000 plants ha-1) were allocated in the subplots and the three nitrogen rates (80, 100, 120 and 140 kg ha-1 N) were allocated in the sub-subplots. Topdress nitrogen was applied using urea as N source. The rise of the plant population from 60,000 to 80,000 plants ha-1 and the application of topdress nitrogen resulted in increased production components. The application of topdress fertilization provided increase in leaf N content and grain yield for the spacings 0.45 m and 0.90 m. Yield was higher in the spacing 0.45 m than 0.90 m. Yield was higher with 60,000 plants than with 80,000 plants at 0.90 m, while at 0.45 m there was no difference in relation to the plant density.

Agronomic performance of common bean in straw mulch systems and topdressing nitrogen rates in no-tillage

ABSTRACTIn no-tillage systems, straw coverage on soil surface is the key to success, and the choice of crops for rotation is crucial to achieve the sustainability and quality that conservation agriculture requires. The objective of this study was to evaluate the agronomic performance of the common bean cultivar IAC Formoso sown in succession to three straw mulch systems (corn alone, corn/Urochloa ruziziensisintercrop and U. ruziziensisalone) and topdress nitrogen rates (0; 40; 80; 120 and 160 kg ha-1N), at the four-leaf stage, three years after the implementation of no-tillage. The experiment was arranged in a randomized block split plot design, with three replications. Common bean highest yields were achieved in succession to U. ruziziensisalone and intercropped with corn. The corn/U. ruziziensisintercrop provided both straw and seed production, allowing for quality no-tillage. Topdressed nitrogen influenced the common bean yield when in succession to corn alone, U. ruziziensisalone and corn/U. ruziziensisintercrop in no-tillage.

Upland rice under no-tillage preceded by crops for soil cover and nitrogen fertilization

The grain yield of upland rice under no-tillage has been unsatisfactory and one reason could be the nitrate/ammonium balance in the soil. Cover crops and nitrogen fertilization can be used to change the nitrate/ammonium relation in the soil and improve conditions for the development of upland rice in the no-tillage (NT) system. The aim was to study the effect of cover crops and nitrogen sources on grain yield of upland rice under no tillage. The study was carried out on the Fazenda Experimental Lageado, in Botucatu, State of São Paulo, Brazil, in an Oxisol area under no-tillage for six years. The experiment was arranged in a randomized block split-plot design with four replications. The plots consisted of six cover crop species (Brachiaria brizantha, B. decumbens, B. humidicola, B. ruziziensis, Pennisetum americanum, and Crotalaria spectabilis) and the split-plots of seven forms of N fertilizer management. Millet is the best cover crop to precede upland rice under NT. The best form of N application, as nitrate, is in split rates or total rate at topdressing or an ammonium source with or without a nitrification inhibitor, in split doses. When the cover crops C. spectabilis, B. brizantha, B. decumbens, B. humidicola, and B. ruziziensis preceded rice, they induced the highest grain yield when rice was fertilized with N as ammonium sulfate source + nitrification inhibitor in split rates or total dose at topdressing.

Cover Crops and Nitrogen Fertilization Effects on Nitrogen Soil Fractions under Corn Cultivation in a No-Tillage System

ABSTRACT The use of cover crops has recently increased and represents an essential practice for the sustainability of no-tillage systems in the Cerrado region. However, there is little information on the effects of nitrogen fertilization and cover crop use on nitrogen soil fractions. This study assessed changes in the N forms in soil cropped to cover crops prior to corn growing. The experiment consisted of a randomized complete block design arranged in split-plots with three replications. Cover crops were tested in the plots, and the N topdressing fertilization was assessed in the subplots. The following cover species were planted in succession to corn for eight years: Urochloa ruziziensis, Canavalia brasiliensis M. ex Benth, Cajanus cajan (L.) Millsp, and Sorghum bicolor (L.) Moench. After corn harvesting, the soil was sampled at depths of 0.00-0.10 and 0.10-0.20 m. The cover crops showed different effects at different soil depths. The soil cultivated with U. ruziziensis showed higher contents of total-N and particulate-N than the soil cultivated with C. cajan. Particulate-N was the most sensitive to changes in the soil management among the fractions of N assessed. The soil under N topdressing showed a lower content of available-N in the 0.10-0.20 m layer, which may be caused by the season in which the sampling was conducted or the greater uptake of the available-N by corn.

Influence of nitrogen fertilization and green manure on the economic feasibility of no-tilled wheat in the Cerrado

É importante a busca por melhores rentabilidades para a cultura do trigo por meio de tecnologias que reduzam custos de produção e proporcionem sustentabilidade à agricultura brasileira. Assim, o objetivo deste trabalho foi avaliar a rentabilidade da cultura do trigo em sistema plantio direto, visando reduzir doses de nitrogênio em cobertura, pelo cultivo de adubos verdes anterior ao do trigo. O experimento foi realizado em Selvíria (MS), Brasil, no ano 2009/10. O delineamento utilizado foi o de blocos casualizados com 36 tratamentos, em parcelas subdividas, com quatro repetições. As parcelas foram formadas por seis tipos de adubos verdes (guandu BRS Mandarim, Crotalaria juncea, milheto BRS 1501, pousio e os consórcios milheto + guandu e milheto + crotalária), que forneceram palha para o plantio direto do trigo no inverno, após a cultura de arroz na safra de verão. As subparcelas foram formadas por seis doses de nitrogênio (0, 25, 50,75, 100 e 125 kg ha-1 de N) em uma aplicação em cobertura, ten-do como fonte a ureia. O trigo cultivado, após a semeadura dos adubos verdes na safra de inverno anterior, sem a aplicação de nitrogênio em cobertura e na dose 25 kg ha-1 de N, apresentou com maior frequência custos de produção superior à receita bruta. O custo de produção de trigo cultivado após os consórcios de milheto + guandu e milheto + crotalária na safra de inverno anterior, associado a doses de nitrogênio de 50 e 75 kg ha-1 de N, proporcionou maior lucratividade em relação aos demais adubos verdes avaliados.

Upland rice under no-tillage preceded by crops for soil cover and nitrogen fertilization

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cover Crops and Nitrogen Fertilization Effects on Nitrogen Soil Fractions under Corn Cultivation in a No-Tillage System.

ABSTRACT: The use of cover crops has recently increased and represents an essential practice for the sustainability of no-tillage systems in the Cerrado region. However, there is little information on the effects of nitrogen fertilization and cover crop use on nitrogen soil fractions. This study assessed changes in the N forms in soil cropped to cover crops prior to corn growing. The experiment consisted of a randomized complete block design arranged in split-plots with three replications. Cover crops were tested in the plots, and the N topdressing fertilization was assessed in the subplots. The following cover species were planted in succession to corn for eight years: Urochloa ruziziensis, Canavalia brasiliensis M. ex Benth, Cajanus cajan (L.) Millsp, and Sorghum bicolor (L.) Moench. After corn harvesting, the soil was sampled at depths of 0.00-0.10 and 0.10-0.20 m. The cover crops showed different effects at different soil depths. The soil cultivated with U. ruziziensis showed higher contents of total-N and particulate-N than the soil cultivated with C. cajan. Particulate-N was the most sensitive to changes in the soil management among the fractions of N assessed. The soil under N topdressing showed a lower content of available-N in the 0.10-0.20 m layer, which may be caused by the season in which the sampling was conducted or the greater uptake of the available-N by corn.

Economic viability of doses and split-applications of nitrogen fertilization in corn crop in a eutrophic Red Latosol

Nitrogen is the nutrient that is most absorbed by the corn crop, with the most complex management, and has the highest share on the cost of corn production. The objective of this work was to evaluate the economic viability of different rates and split-applications of nitrogen fertilization, as such as urea, in the corn crop in a eutrophic Red Latosol (Oxisol). The study was carried out in the Experimental Station of the Regional Pole of the Sao Paulo Northwest Agribusiness Development (APTA), in Votuporanga, State of Sao Paulo, Brazil. The experimental design was randomized complete blocks with nine treatments and four replications, consisting of five N rates: 0, 55, 95, 135 and 175 kg ha(-1), 15 kg ha-l applied in the seeding and the remainder in top dressing: 40 and 80 kg ha(-1) N at forty days after seeding (DAS), or 1/2 + 1/2 at 20 and 40 DAS; 120 kg ha-1 N split in 1/2 + 1/2 or 1/3 + 1/3 + 1/3 at 20, 40 or 60 DAS; 160 kg ha(-1) N split in 1/4 + 3/8 + 3/8 or 114 + 1/4 + 1/4 + 1/4 at 20, 40, 60 and 80 DAS. The application of 135 kg ha-l of N split in three times provided the best benefit/cost ratio. The non-application of N provided the lowest economic return, proving to be unviable.

Macronutrients in Marandu Palisade Grass as Influenced by Lime, Slag, and Nitrogen Fertilization

Soil acidity is one of the main limiting factors for the growth of pasture grasses in Brazilian soils. In addition to lime, slag can be used to correct soil acidity and help plants to absorb nutrients in adequate amounts. The objective of this experiment was to evaluate, under greenhouse conditions, the effects of slag and lime plus nitrogen (N) on marandu palisade grass plants` nutritional status as well as the absorption of macronutrients submitted to two cuts. The treatments consisted of two corrective materials (slag and lime), three corrective material rates (0.81, 1.61, and 3.22 g dm-3 of ECaCO3), three N rates (75, 150, and 300 mg dm-3) plus a control treatment, with four replications. Macronutrient contents in the forage plants were found to be present in adequate levels. The mean value of N accumulated in the shoot was 40.1 mg per plant, phosphorus (P) was 4.6 mg per plant, potassium (K) was 38.6 mg per plant, calcium (Ca) was 7.3 mg per plant, magnesium (Mg) was 6.7 mg per plant, and sulfur (S) was 3.5 mg per plant at the first cut. At the second cut, the nutrient accumulations values were N 50.8 mg per plant, P 6.3 mg per plant, K 20.7 mg per plant, Ca 21.6 mg per plant, Mg 24.0 mg per plant, and S 4.7 mg per plant. Macronutrients accumulation in the shoot of grass increased with the addition of both the correctives as well as the N rates.

Simulation of irrigated Thanzania grass growth based on photothermal units, nitrogen fertilization and water availability

Simulation of irrigated Thanzania grass growth based on photothermal units, nitrogen fertilization and water availability. The mathematical model to predict the forage yield using photothennal units was utilized with success in Elephant grass, Thanzania and Brachiaria niziziensis in the absence of water stress and nitrogen stress. The aim of this study was to propose models to estimate the forage yield of Thanzania grass under different irrigation (25, 50,75, 100 e 125% of ETc) and nitrogen level in various regions of Brazil. As such, models were developed to estimate the dry matter production of Panicum maximum Jacq. frass cv Thanzania in different irrigation and nitrogen levels, using photothermal units. The models were adjusted to doses of 0, 30, 60, 110 and 270 kg of N ha(-1), doses were divided in applications after each evaluation, with a rest cycle of 35 days. The adjusted model presented good performance in predicting dry matter production of Thanzania grass, with r(2) = 0.9999. The results made it possible to verify that the proposed model can be used to predict forage production in different regions of Brazil. It can be estimated, with good precision. The production of Thanzania grass dry matter can be accurately estimated in specific places (in function of latitude and time of year), with the maximum and minimum temperature values.

Nitrogen fertilization in common bean crops under no-tillage and conventional systems.

Nitrogen fertilization in common bean crops under no-tillage and conventional systems. Nitrogen fertilizer is necessary for high yields in common bean crops and N responses under conditions of no-tillage and conventional systems are still basic needs. Thus, the objective of this research was to evaluate the effect of N application and common bean yield in no-tillage and conventional systems. The experimental design was a randomized block in a factorial scheme (2x8+1) with four replications. The treatments were constituted by the combination of two N doses (40 and 80 kg ha(-1)) applied at side dressing at eight distinct stadia during vegetative development of the common bean (V(4-3), V(4-4), V(4-5), V(4-6), V(4-7), V(4-8), V(4-9) and V(4-10)), in addition to a control plot without N in side dressing. The experiment was conducted over two years (2002 and 2003) in no-tillage on millet crop residues and conventional plow system. It was concluded that N fertilizer at the V(4) stadium of common bean promotes similar seed yields in no-tillage and conventional systems. Yield differences between no-tillage and conventional systems are inconsistent in the same agricultural area.

Nitrogen fertilization of coffee: organic compost and Crotalaria juncea L.

Information concerning the response of coffee to organic fertilizers is scarce. This study evaluates the effect of different doses of compost and Crotalaria juncea L. on growth, production and nitrogen nutrition of coffee trees. The treatments consisted of compost at rates of 25, 50, 75 and 100% of the recommended fertilization, with or without the aerial part of C. juncea. C. juncea was grown with NH4-N (2% 15N) and applied to coffee. The use of C. juncea increased growth in height and diameter of the coffee canopy. In the first year, the percentage of N derived from C. juncea reached 8.5% at seven months and 4.1% at fifteen months after fertilization. In the second year, the percentage of N derived from C. juncea reached 17.9% N at the early harvest, five months after fertilization. Increased rates of compost increased pH , P , K , Ca , Mg , sum of bases , effective CEC, base saturation and organic matter and reduced potential acidity. 15N allowed the identification of the N contribution from C. juncea with percentage of leaf N derived from Crotalaria juncea from 9.2 to 17.9%.

Maize nitrogen fertilization in two crop rotation systems under no-till

The objective of this study was to evaluate split nitrogen (N) fertilization of maize applied in band at sowing and top dressing with and without crop rotation, under no-till. The experiment was conducted with six N rates at sowing (0, 20, 30, 40, 50 and 60 kg ha-1) combined with three rates in top dressing (40, 70, 100 kg ha-1) and two management systems: after five cropping sequences of maize and crop rotation (maize + soybean + oat + soybean + corn) in a randomized block design with four replications. The crop rotation system increased yield in approximately 7% in relation to the area without rotation. The split of nitrogen fertilization, in rates above 39 and 54 kg ha-1 at sowing and 70 and 40 kg ha-1 in top dressing, resulted in yield higher than that obtained with the application of 100 kg ha-1 in top dressing. Grain yield was higher with the rates 50 and 70 kg ha-1 of N compared with that obtained with 20 and 100 kg ha-1 at sowing and top dressing, respectively. The rate 70 kg ha-1 of N resulted in the highest yield at the lowest cost compared with the revenues and costs incurred with the rates 40 and 100 kg ha-1.