Adônis Moreira

Foliar Fertilization of Crop Plants

ABSTRACT Essential plant nutrients are mainly applied to soil and plant foliage for achieving maximum economic yields. Soil application method is more common and most effective for nutrients, which required in higher amounts. However, under certain circumstances, foliar fertilization is more economic and effective. Foliar symptoms, soil and plant tissue tests, and crop growth responses are principal nutrient disorder diagnostic techniques. Soil applications of fertilizers are mainly done on the basis of soil tests, whereas foliar nutrient applications are mainly done on the basis of visual foliar symptoms or plant tissue tests. Hence, correct diagnosis of nutrient deficiency is fundamental for successful foliar fertilization. In addition, there are some more requirements for successful foliar fertilization. Foliar fertilization requires higher leaf area index for absorbing applied nutrient solution in sufficient amount, it may be necessary to have more than one application depending on severity of nutrient deficiency. Nutrient concentration and day temperature should be optimal to avoid leaf burning and fertilizer source should be soluble in water to be more effective. Foliar fertilization of crops can complement soil fertilization. If foliar fertilization is mixed with postemergence herbicides, insecticides, or fungicides, the probability of yield response could be increased and cost of application can be reduced.

Soil Fertility and Production Potential

Despite important regional differences, some general properties with respect to fertility are common to most Amazonian Dark Earths: high total P and Ca contents and availability as well as often low N and K availability. The information compiled in this chapter explains the extent and mechanisms of the high fertility of Amazonian Dark Earths. However, the authors do not intend to advocate an exploitation of the high fertility of Amazonian Dark Earths, but rather to document the fertility potential of these special soils — highly weathered yet fertile — as well as to understand the properties of such soils with enhanced fertility. Contemporary efforts to develop sustainable landuse technologies should consider evidence provided by ADE research, regardless of whether ADE were intentionally made or not. Management to create fertile soils in the humid tropics has to consider the importance of organically bound nutrients that show low leaching combined with high availability similar to the properties shown here for Amazonian Dark Earths.

YIELD AND YIELD COMPONENTS OF UPLAND RICE AS INFLUENCED BY NITROGEN SOURCES

Ammonium sulfate and urea are main sources of nitrogen (N) for annual crop production in developing countries. Two greenhouse experiments were conducted using ammonium sulfate and urea as N sources for upland rice grown on a Brazilian Oxisol. The N rates used were 0, 50, 100, 150, 3000, and 400 kg N kg−1 of soil. Yield and yield components were significantly increased in a quadratic fashion with increasing N rate. Ammonium sulfate X urea interaction was significant for grain yield, shoot dry matter yield, panicle number, plant height and root dry weight, indicating a different response magnitude of these plant parameters to two sources of N. Based on regression equation, maximum grain yield was achieved with the application of 380 mg N kg−1 by ammonium sulfate and 271 mg N kg−1 by urea. Grain yield and yield components were reduced at higher rates of urea (>300 mg kg N) but these plant parameters’ responses to ammonium sulfate at higher rates was constant. In the intermediate N rate range (125 to 275 mg kg−1), urea was slightly better compared to ammonium sulfate for grain yield. Grain yield was significantly related with plant height, shoot dry weight, panicle number, grain harvest index and root dry weight. Hence, improving these plant characteristics by using appropriate soil and plant management practices can improve upland rice yield.

Soil Chemical Attributes of Amazonas State, Brazil

Amazonas State is the largest state in Brazil and mainly covered by tropical forest. Because of the importance of the tropical forest in maintaining soil health and a clean environment, conservation of the Amazon forest is a national priority. However, sustainable agriculture development is necessary in the state for the welfare of the local population. Maintaining soil fertility at an adequate level is an important component of sustainable farming. Very little information is available about soil fertility of Amazonas State. The objective of the present study was to evaluate chemical soil properties of Amazonas State of Brazil. Results include chemical properties of 3,340 samples, covering 62 municipalities of the state collected at 0–20 cm deep during 30 years (1975–2005). Chemical properties [phosphorus (P), potassium (K) extracted with Mehlich 1, calcium (Ca), magnesium (Mg), aluminum (Al) extracted with potassium chloride (KCl) 1.0 mol L−1, potential acidity (H + Al) extracted with calcium acetate, and base saturation] presented great variation, except cation exchange capacity (CEC) and pH (water). Most of the soil samples were characterized as having high acidity; medium level of organic‐matter content; low levels of P, K, Ca, and Mg; and high levels of Al and H + Al. Overall, base saturation was less than 20%, a value considered very low for most of annual crops. Soils from upland areas were more acidic and have poor fertility compared with lowland soils. To maintain sustainability of cropping systems, use of an adequate level of liming and chemical fertilizers are necessary on these soils.

Yield, nutrient uptake, and soil chemical properties as influenced by liming and boron application in common bean in a no-tillage system

Soil acidity is the principal limiting factor in crop production in Oxisols, and deficiency of micronutrients has increased in recent years because of intensive cropping. A field experiment was conducted over three consecutive years to assess response of common bean (Phaseolus vulgaris L.) to lime and iron (Fe) applications on an Oxisol in a no-tillage system. Changes in selected soil chemical properties in the soil profile (0- to 10- and 10- to 20-cm depths) with liming were also determined. Lime rates used were 0, 12, and 24 Mg ha–1, and Fe application rates were 0, 50, 100, 150 200, and 400 kg ha–1. Both lime and Fe were applied as broadcast and incorporated in the soil. Grain yields of common bean were significantly increased with the application of lime. Iron application, however, did not influence bean yield. There were significant changes in soil profile (0- to 10-cm and 10- to 20-cm depths) in pH, calcium (Ca2+), magnesium (Mg2+), hydrogen + aluminum (H+ + Al3+), base saturation, acidity saturation, cation exchange capacity (CEC), Ca2+ saturation, Mg2+ saturation, potassium (K+) saturation, and ratios of Ca/Mg, Ca/K, and Mg/K. These soil chemical properties had significant positive association with common bean grain yield. Averaged across two depths and three crops, common bean produced maximum grain yield at pHw 6.3, Ca2+ 3.8 cmolc kg–1, Mg2+ 1.1 cmolc kg–1, 3.5 H+ + Al3+ cmolc kg–1, acidity saturation 41.8%, CEC 7.5 cmolc kg–1, base saturation 57.4%, Ca saturation 45.2%, Mg saturation 14.2%, K saturation 9.1%, Ca/Mg ratio 3.1, Ca/K ratio 22.6, and Mg/K ratio 6.7.

Dry bean genotypes evaluation for growth, yield components and phosphorus use efficiency.

Dry bean along with rice is a staple food for the population of South America. In this tropical region beans are grown on Oxisols and phosphorus (P) is one of the most yield limiting factors for dry bean production on these soils. A greenhouse experiment was conducted to evaluate P use efficiency in 20 elite dry bean genotypes grown at deficient (25 mg P kg−1 soil) and sufficient (200 mg P kg−1) levels of soil P. Grain yields and yield components were significantly increased with P fertilization and, interspecific genotype differences were observed for yield and yield components. The grain yield efficiency index (GYEI) was having highly significant quadratic association with grain yield. Based on GYEI most P use efficient genotypes were CNFP 8000, CNFP 10035, CNFP10104, CNFC 10410, CNFC 9461, CNFC 10467, CNFP 10109 and CNFP 10076 and most inefficient genotypes were CNFC 10438, CNFP 10120, CNFP 10103, and CNFC 10444. Shoot dry weight, number of pods per plant, 100-grain weights and number of seeds per pod was having significant positive association with grain yield. Hence, grain yield of dry bean can be improved with the improvement of these plant traits by adopting appropriate management practices. Soil pH, extractable P and calcium (Ca) saturation were significantly influenced by P treatments. Based on regression equation, optimum pH value in water was 6.6, optimum P in Mehlich 1 extraction solution was 36 mg kg−1 and optimum Ca saturation value was 37% for dry maximum bean yield.

Dinâmica da matéria orgânica e da biomassa microbiana em solo submetido a diferentes sistemas de manejo na Amazônia Ocidental

The objective of this work was to evaluate the alterations of the microbial biomass activity as an indicator of C and N dynamics in a soil submitted to the succession of plant cover and management in the Western Amazon. The work was carried out in two chronosequences: CA - a succession from primary forest to a three years old cupuacu (Theobroma grandiflorum) plot - and CB - a succession from primary forest to an eight years old Brachiaria humidicola pasture and a three years old cupuacu plot. The succession primary forest-pasture-cupuacu affects negatively the stock of the soil carbon, with significant decrease of organic matter and C of the soil microbial biomass. The primary forest presents lower metabolic quotient and higher C/N ratio of the biomass, which results in less carbon loss. The N of the microbial biomass found in the 0-10 cm layer irrespective of the management adopted, increases significantly in the cupuacu plot and the total N decreases. Ammonium concentration decreases according to soil depth, but this does not occur with nitrate.

Phosphorus management for perennial crops in central Amazonian upland soils

The present contribution discusses the soil P status of central Amazonian upland soils, the effects of tree crops on soil P availability and the factors controlling soil P cycling in land use systems with tree crops. Soil fertility management has to target the prevalent P deficiency by adequate P fertilization, especially in southern and northern municipalities of central Amazônia where the largest areas with severe P deficiency are found. P fixation to clay minerals is not a major obstacle for P management in the highly weathered upland soils of the central Amazon due to their low Al- and Fe-oxide contents. Low total soil P amounts are mainly responsible for low P availability. Tree crops are found to be especially suitable for land use under low-P-input conditions. Their large P return to soil by litterfall and pruning improves soil P availability. Additionally, litter quality affects P release and soil P availability. Both aspects, quantity and quality effects, are strongly dependent on tree species. Phosphorus sorption does not seem to be reduced by different litter types confirming earlier results that P fixation is not a major problem in central Amazonian upland soils. In conclusion, biological approaches are more important than physical approaches to improve soil P availability in central Amazonian Oxisols. With large P cycling through soil microbial biomass and between plant and soil, a higher availability of added P can be maintained and P applications only need to replenish P exports by harvest. Low P additions will improve productivity also for long-term uptake by trees. This is of high importance in regions with poor infrastructure and the lack of financial resources.

Boron and water stress on yield of sunflower

Com este trabalho, objetivou-se estudar sob condicoes de casa-de-vegetacao, o efeito da interacao doses boro e estresse hidrico na producao de materia seca total, producao de aquenios e conteudo de oleo em girassol cultivado em Latossolo Vermelho Amarelo distrofico de textura media. O delineamento experimental utilizado foi o de blocos ao acaso, em esquema fatorial 4 x 4, com quatro repeticoes. Foram estudadas quatro doses de B: 0, 0,25, 0,5 e 2,0 mg kg-1, aplicado na forma de acido borico e quatro fases de controle de umidade: sem estresse hidrico durante o ciclo, com estresse hidrico durante o ciclo, estresse hidrico a partir do florescimento e estresse hidrico a partir do enchimento de aquenios. Os resultados mostraram que, independentemente da fase de aplicacao ou nao de estresse hidrico, a dose 0,5 mg dm-3 de B acarretou na maior producao de materia seca total, producao de aquenios e rendimento de oleo por capitulo. A aplicacao de estresse hidrico a partir do inicio do florescimento ou no enchimento de aquenios acarreta em menor producao de materia seca total, de aquenios e de oleo.Com este trabalho, objetivou-se estudar sob condicoes de casa-de-vegetacao, o efeito da interacao doses boro e estresse hidrico na producao de materia seca total, producao de aquenios e conteudo de oleo em girassol cultivado em Latossolo Vermelho Amarelo distrofico de textura media. O delineamento experimental utilizado foi o de blocos ao acaso, em esquema fatorial 4 x 4, com quatro repeticoes. Foram estudadas quatro doses de B: 0, 0,25, 0,5 e 2,0 mg kg-1, aplicado na forma de acido borico e quatro fases de controle de umidade: sem estresse hidrico durante o ciclo, com estresse hidrico durante o ciclo, estresse hidrico a partir do florescimento e estresse hidrico a partir do enchimento de aquenios. Os resultados mostraram que, independentemente da fase de aplicacao ou nao de estresse hidrico, a dose 0,5 mg dm-3 de B acarretou na maior producao de materia seca total, producao de aquenios e rendimento de oleo por capitulo. A aplicacao de estresse hidrico a partir do inicio do florescimento ou no enchimento de aquenios acarreta em menor producao de materia seca total, de aquenios e de oleo.

NUTRIENT BIOAVAILABILITY IN SALT AFFECTED SOILS

Salt affected soils limit crop yields around the world. Knowledge of how nutrient availability is affected in plants growing on salt affected soils is important in adopting appropriate management practices to satisfy plants’ nutritional requirements and improve yields to meet food demands of increasing world populations. In the salt affected environment plants required to absorb essential nutrients from a dilute source in the presence of highly concentrated nonessential nutrients. Nutrient uptake and use efficiency in salt affected soils is low due to salt stress and negative interactions with cations and anions present in high concentrations. Hence, a higher amount of nutrients is necessary in salt affected soils compared to normal soils. Biological nitrogen fixation is also adversely affected in legumes grown on salt affected soils. Salts also reduce activity of many enzymes which supply energy for nutrient uptake. The important soils and plant management practices which can improve nutrient uptake and use efficiency in salt affected soils are use of soil amendments to reduce effect of salts, application of farmyard manures to create favorable plant growth environments, leaching salts from soil profile and planting salt tolerant crop species or genotypes within species. Addition of fertilizers, especially potassium may also help in reducing salinity effects and improving nutrient use efficiency.