Comparative Efficiency of Phosphorus Sources for Upland Rice Production

Rice (Oryza sativa L.) is a staple food for more than 50% of the world’s population, and phosphorus (P) is one of the most yield-limiting nutrients for rice production in tropical acidic soils worldwide. A greenhouse experiment was conducted to evaluate efficiency of six P sources for upland rice production. The P sources used were simple superphosphate (SSP), polymer-coated SSP (PSSP), triple superphosphate (TSP), polymer-coated TSP (PTSP), monoammonium phosphate (MAP), and polymer-coated MAP (PMAP). There were four P rates [50, 100 200, and 400 mg phosphorus (P) kg^?1] applied with four sources plus one control treatment [0 mg phosphorus (P) kg^?1]. Plant height, straw yield, grain yield, panicle density, root dry weight, maximum root length, and 1000-grain weight were significantly increased with increasing P rates in the range of 0 to 400 mg P kg^?1. However, P-use efficiency (mg grain produced per mg P applied) was decreased with increasing P rate. Based on regression equation, overall maximum plant height was obtained with the application of 235 mg P kg^?1, maximum straw yield with the application of 265 mg P kg^?1, and maximum grain yield at 227 mg P kg^?1. Based on maximum grain yield, the P source were classified as PMAP > SSP = MAP > PSSP > TSP > PTSP in the upland rice production efficiency. Overall, maximum panicle density was obtained with the addition of 231 mg P kg^?1 and maximum 1000-weight was obtained with the addition of 226 mg P kg^?1. Similarly, overall root dry weight and maximum root length were achieved with the application of 261 and 298 mg P kg^?1 of soil. Most of the growth and yield components had a significant positive association with grain yield. Optimum soil acidity indices such as pH; exchangeable calcium (Ca), magnesium (Mg), and potassium (K); Ca, Mg, and K saturation; base saturation; and acidity saturation were established for maximum upland rice grain yield.     

Phosphorus Nutrition of Lowland Rice in Tropical Lowland Soil

Rice is a main food crop for about half of the world's population, and phosphorus (P) is the main limiting nutrient in rice production in tropical lowlands. A greenhouse experiment was conducted to evaluate P requirements of lowland rice grown on a lowland soil (Inceptisol). Dry matter, grain yield, and yield-attributing characteristics were significantly (P < 0.01) influenced by P fertilization. Based on quadratic response, maximum shoot dry weight and grain yield were obtained with the application of 190 mg P kg^?1 of soil. Maximum panicle, tiller number, and plant height were obtained with the application of 177 192, and 175 mg P kg^?1 of soil, respectively. Mehlich 1–extractable P for maximum grain yield was 15.6 mg kg^?1 of soil. Variability in grain yield with plant growth and yield parameters was in the order of tiller > shoot dry weight > panicle number > spikelet sterility > plant height > grain harvest index > panicle length > weight of 1000 grains. Phosphorus uptake in shoot and concentration and uptake in grain significantly (P < 0.01) increased grain yield. However, variability in grain yield was greater with concentration and uptake of P in the grain. Similarly, P harvest index was also significantly associated with grain yield. Agronomic P-use efficiency, apparent P-recovery efficiency, and P-utilization efficiency decreased quadratically with increasing P rates, whereas physiological P-use efficiency increased quadratically and agrophysiological P-use efficiency decreased linearly with increasing P rates. Agrophysiological and utilization P-use efficiencies had significant positive correlation with grain yield.     

Comparative Efficiency of Nitrogen Sources for Lowland Rice Production

Rice (Oryza sativa L.) is the staple food for more than 50% world population and nitrogen (N) is one of the most yield-limiting nutrients for rice production worldwide. A greenhouse experiment was conducted to evaluate the efficiency of three N sources for lowland rice production. The N sources used were ammonium sulfate, common urea, and polymer-coated urea. There were three N rates, i.e. 100, 200, and 400 mg N kg^?1 applied with three sources plus one control treatment (0 mg N kg^?1). Growth, yield, and yield components were significantly increased either in a linear or quadratic fashion with the addition of N fertilizers in the range of 0–400 mg kg^?1 soil. Maximum grain yield was obtained with the addition of ammonium sulfate at 100, 200, and 400 mg kg^?1 of soil. Common urea and polymer-coated urea were more or less similar in grain production at 100 and 200 mg N kg^?1. However, at 400 mg N kg^?1 treatments, polymer-coated urea produced the lowest grain yield. Most of the growth and yield components were positively related to grain yield, except spikelet sterility which was negatively related to grain yield. Nitrogen use efficiency decreased with increasing N rate in all the three N sources. Maximum N use efficiency was obtained with the addition of ammonium sulfate at lower as well as at higher N rates compared with other two N sources.     

Phosphorus Nutrition of Upland Rice,Dry Bean,Soybean, and Corn Grown on an Oxisol

Rice, dry bean, corn, and soybean are important food crops. Phosphorus (P) deficiency is one of the most yield-limiting factors for these crops grown on highly weathered Brazilian Oxisols. Four greenhouse experiments were conducted to determine P requirements of these four crops. The P levels used were 0, 50, 100, 200, and 400 mg kg^?1. Growth, yield, and yield components evaluated of four crop species were significantly increased with the application of P fertilization. Most of the responses were quadratic in fashion when the P was applied in the range of 0 to 400 mg kg^?1. Maximum grain yield of upland rice was obtained with the application of 238 mg P kg^?1 of soil, maximum dry bean grain yield was obtained with the application of 227 mg P kg^?1 of soil, and maximum grain yield of soybean was obtained with the application of 224 mg P kg^?1 of soil. Maximum shoot growth of corn was obtained with the addition of 323 mg P kg^?1 of soil. Most of the growth and yield components had significant positive association with grain yield or shoot dry weight. Phosphorus concentration and uptake were greater in the grain compared to straw in upland rice and dry bean plants. Overall, P-use efficiencies decreased with increasing P rates.     

Agronomic Efficiency of Two Types of Lime and Phosphate Fertilizer Sources in Brazilian Cerrado Soils Cultivated with Soybean

With the increase in phosphate fertilizer prices, there is a need to find lower-cost alternatives that are as efficient as soluble sources such as single (SSP) and triple superphosphate (TSP). In Brazil’s northern and northeastern regions, there are reserves of igneous rocks with low solubility containing high concentrations of total phosphorus (P) that can be used to produce fertilizers, such as thermalphosphates. To assess the efficiency of sources of P and two types of lime on soybean yield, a field experiment was carried out in an area with dystrophic Red Latosol (Oxisol) in a Cerrado region in the southern part of Maranhão State. The experimental design was randomized blocks in a 2 × 3 × 4 factorial scheme, with four replicates. The treatments were two types of lime [calcitic (CL) (<5 dag kg^?1 of MgO) and dolomitic (DL) (>13 dag kg^?1 of MgO)], three phosphate fertilizer sources [triple superphosphate (TSP), “Yoorin” thermalphosphate (YT), and experimental thermalphosphate (ET)], and four rates of phosphorus pentoxide (P₂O₅; 0, 100, 200, and 300 kg ha^?1). After 2 years of cultivation, the application of DL resulted in greater soybean yields than the application of CL. The two lime types influenced the pH, carbon (C), calcium (Ca), and magnesium (Mg) concentrations as well as the Ca/Mg, Ca/K, and Mg/K ratios in the soil. With respect to sources of P, the YT applied in the soil with DL produced an agronomic efficiency index (AEI) similar to that of TSP, whereas in the soil with CL, the TSP, YT, and ET were similar, with maximum technical efficiency (MTE) under both conditions starting at 230 kg ha^?1 of P₂O₅. The critical concentration of available phosphorus (P) in the soil (Mehlich-1 extractant) for cultivation of soybean under the climate and soil conditions studied was between 5.0 and 6.0 mg kg^?1.     

Response of Soybean to Phosphorus Fertilization in Brazilian Oxisol

Soybean is an important grain crop for Brazil, and phosphorus (P) plays an important role in improving yield of this crop in Brazilian Oxisols. Data are limited on influence of P sources and rate on soybean yield, yield components, and P-use efficiency. A field experiment was conducted for 3 consecutive years to determine response of soybean to three fertilizers (single superphosphate, Yoorin, and Arad) with 0, 17.5, 35, and 52.5 kg P ha^?1 (0, 40, 80 and 120 kg P₂O₅ ha^?1). Grain yield was significantly influenced by phosphorus fertilization. Overall, maximum grain yield was produced by application of single superphosphate, followed by Yoorin and Arad. Number of grains per pod and 100-grain weights were also influenced significantly by P fertilization. Shoot dry weight, number of pods per plant, and grain harvest index had a significant positive association with grain yield. Phosphorus uptake in grain was about six times more than uptake in shoots, and P uptake in grain had a significant positive association with grain yield. Phosphorus-use efficiency (kg grain/kg P applied or uptake) decreased with increasing P rate, and it was greater for single superphosphate than for Yoorin and Arad sources of P fertilization. However, P-utilization efficiency (kg grain plus straw yield / P uptake in grain plus straw) was greater under Yoorin treatment compared to the two other sources of P.     

Optimal Acidity Indices for Soybean Production in Brazilian Oxisols

Soybean is an important crop for the Brazilian economy, and soil acidity is one of the main yield-limiting factors in Brazilian Oxisols. A field experiment was conducted during three consecutive years with the objective to determine soybean response to liming grown on Oxisols. Liming rates used were 0, 3, 6, 12, and 18 Mg ha^?1. Liming significantly increased grain yield in a quadratic trend. Ninety percent maximum economic grain yield (2900 kg ha^?1) was achieved with the application of about 6 Mg lime ha^?1. Shoot dry weight, number of pods per plant, and 100-grain weight were also increased significantly in a quadratic fashion with increasing liming rate from 0 to 18 Mg ha^?1. These growth and yield components had a significant positive association with grain yield. Maximum contribution in increasing grain yield was of number of pods per plant followed by grain harvest index and shoot dry weight. Uptake of nitrogen (N) was greatest and phosphorus (P) was least among macronutrients in soybean plant. Nutrient-use efficiency (kg grain per kg nutrient accumulation in grain) was maximum for magnesium (Mg) and lowest for N among macronutrients. Application of 3 Mg lime ha^?1 neutralized all aluminum ions in soil solution. Optimal acidity indices for 90% of maximum yield were pH 6.0, calcium (Ca) 1.6 cmol_c kg^?1, Mg 0.9 cmol_c kg^?1, base saturation 51%, cation exchange capacity (CEC) 4.8 cmol_c kg^?1, Ca/Mg ratio 1.9, Ca?/?potassium (K) ratio 5.6, and Mg/K ratio 3.0.     

Comparison of Conventional and Polymer Coated Urea as Nitrogen Sources for Lowland Rice Production

Nitrogen (N) is one of the most yield limiting nutrients in lowland rice production. Improving N use efficiency is essential to reduce cost of crop production and environmental pollution. A greenhouse experiment was conducted with the objective to compare conventional and polymer coated urea for lowland rice production. Grain yield, straw yield, panicle density, maximum root length, and root dry weight were significantly increased in a quadratic fashion with the increase of N rate from 0 to 400 mg kg^?1 soil. Nitrogen source X N rate interactions for most of these traits were not significant, indicating that lowland rice responded similarly to change in N rates of two N sources. Based on regression equations, maximum grain yield was obtained with the application of 258 mg N kg^?1 soil and maximum straw yield was obtained with the addition of 309 mg N kg^?1 soil. Nitrogen use efficiency (grain yield per unit of N applied) was maximum for polymer coated urea compared to conventional urea. Root length and root dry weight improved at an adequate N rate, indicating importance of N fertilization in the absorption of water and nutrients and consequently yield. Polymer coated urea had higher soil exchangeable calcium (Ca) and magnesium (Mg), Ca saturation, Mg saturation, base saturation, and effective cation exchange capacity compared to conventional urea. There was a highly significant decrease in soil exchangeable potassium (K) with increasing N rates at harvest of rice plants.     

Nutrient Uptake in Dry Bean Genotypes

Dry bean is an important legume for human consumption in South America. A greenhouse experiment was conducted to evaluate uptake and use efficiency of macro- and micronutrients by six dry bean genotypes at two P levels (25 and 200 mg kg^?1 soil). Shoot dry weight and grain yield varied significantly among genotypes and significantly increased with increasing phosphorus (P) levels. Grain harvest index (GHI) and 100-grain weight also differ significantly among genotypes and significantly increased with the increasing P levels. Based on grain yield efficiency index (GYEI), genotypes were classified as efficient and inefficient. The most efficient genotype was CNFP 10104, and inefficient genotypes were CNFP 10103 and CNFP 10120. Number of pods per plant and number of seeds per pod increased significantly with the addition of 200 mg P kg^?1 of soil compared to the low level of P (25 mg P kg^?1). Similarly, nitrogen (N), P, calcium (Ca), magnesium (Mg), sulfur (S), zinc (Zn), copper (Cu), and manganese (Mn) concentrations and uptake in the shoot and grain also significantly varied among genotypes. Uptake of macro- and micronutrients was greater under the greater P rate compared to the low P rate. This may be related to greater shoot or grain yield at 200 mg P kg^?1 soil compared to 25 mg P kg^?1 of soil.     

Agronomic Evaluation of Coated and Common Urea in Upland Rice Production

Two greenhouse experiments were conducted simultaneously to evaluate polymer-coated and common urea in upland rice production. The nitrogen (N) levels used for both the N sources were from 0 to 400 mg kg^?1 of soil. Maximum grain yield was obtained with the addition of 167 mg N kg^?1 polymer-coated urea and 238 mg N kg^?1 common urea. Maximum value of other plant traits was obtained with N applied from 233 to 313 mg kg^?1 depending on plant traits and N source. Nitrogen-use efficiency (NUE) decreased with increasing N rate in the two N sources. Based on results of growth, yield, and yield components, and NUE it can be concluded that the N sources were equally effective in upland rice production. Base saturation, pH, and exchangeable calcium (Ca) increased with increasing N rates while iron (Fe), manganese (Mn), and copper (Cu) contents decreased with the increasing N rates.     

Requirement of Micronutrients by Lowland Rice

Lowland or flooded rice is mainly responsible for about 76% of total rice production at global level, yet information on micronutrient requirements for this crop is limited. Six greenhouse experiments were conducted at the National Rice and Bean Research Center of EMBRAPA, Santo Antônio de Goiás, Brazil, to determine requirements of zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), manganese (Mn), and iron (Fe) for lowland rice grown on a Brazilian Inceptisol. The levels of micronutrients used were Zn (0, 10 20, 40, and 80 mg kg^?1), Cu (0, 5, 10, 20, and 40 mg kg^?1), B (0, 5, 10, 20, and 40 mg kg^?1), Mo (0, 2, 4, 8, and 16 mg kg^?1), Mn (0, 50, 100, 300, and 600 mg kg^?1), and Fe (0, 250, 500, 1000, and 2000 mg kg^?1). Grain yield was significantly increased in a quadratic fashion with the addition of Zn, Cu, B, Mo, Mn, and Fe. The adequate rates of micronutrients for maximum grain yield were Zn 33 mg kg^?1, Cu 25 mg kg^?1, B 26 mg kg^?1, Mo 10 mg kg^?1, Mn 250 mg kg^?1, and Fe 1269 mg kg^?1. In addition to grain yield, plant height, straw yield, panicle density, and root growth of lowland rice were also improved with the addition of most of these micronutrients. Improvement in root growth has special significance in improving nutrient-use efficiency under nutrient-stress conditions. Micronutrient-use efficiency (grain yield per unit nutrient applied) was in the order of Cu > Zn > Mn > Fe > Mo > B.     

Nutrient constraint of rainfed rice production in foot slope soil of Guinea Forest in Côte d’Ivoire

Soil nutrient deficiencies can affect rice yield and grain mineral content wherever they occur, but an understanding of their effect on upland rice production in humid forest zone of West Africa is still limited. Therefore, a nutrient omission trial was conducted on foot slope soil in 2003, 2004 and 2005 in Côte d’Ivoire using rice variety WAB 56–104. The effect on rice grain yield (GY) and nutrient content of complete fertilizer (Fc with nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and zinc (Zn)) was compared with Fc from which a specific nutrient was excluded (Fc – N, Fc – P, Fc – K, Fc – Ca, Fc – Mg and Fc – Zn). Before the trial, soil K (0.10 cmol kg^?1) and Mg (0.20 cmol kg^?1) contents were suitable, but available P-Bray I (4.2 mg kg^?1) was found to be deficient. In course of the study, K, Mg and P deficiencies were observed. An antagonistic effect was observed between rice GY and grain concentrations in P, Mg and Ca for treatments Fc – Mg, Fc – P and Fc – K, respectively. Therefore, the use of P, K and Mg fertilizers is recommended for successive cropping seasons in order to rich stable and high rice yield while decreasing of grain concentrations in P, Mg and Ca can be observed.     

Lowland Rice Response to Thermophosphate Fertilization

Abstract

Use of adequate rates of phosphorus (P) in crop production on high‐P‐fixing acid soils is essential because of high crop response to P fertilization and the high cost of P fertilizers. Information on lowland rice response to thermophosphate fertilization grown on Inceptisols is limited, and data are also lacking for soil‐test‐based P fertilization recommendations for this crop. The objective of this study was to evaluate response of lowland rice to added thermophosphate and to calibrate P soil testing for making P fertilizer recommendations. A field experiment was conducted for two consecutive years in central Brazil on a Haplaquept Inceptisol. The broadcast P rates used were 0, 131, 262, 393, 524, and 655 kg P ha^?1, applied as thermophosphate Yoorin. Rice yield and yield components were significantly increased with the application of P fertilizer. Average maximum grain yield was obtained with the application of 509 kg P ha^?1. Uptake of macro‐ and micronutrients had significant quadratic responses with increasing P rates. Application of thermophosphate significantly decreased soil acidity and created favorable macro‐ and micronutrient environment for lowland rice growth. Across 2 years, soil‐test levels of Mehlich 1–extractable P were categorized, based on relative grain yield, as very low (0–17 mg P kg^?1 soil), low (17–32 mg P kg^?1 soil), medium (32–45 mg P kg^?1 soil), or high (>45 mg P kg^?1 soil). Similarly, soil‐test levels of Bray 1–extractable P across 2 years were very low (0–17 mg P kg^?1 soil), low (17–28 mg P kg^?1 soil), medium (28–35 mg P kg^?1 soil), or high (>35 mg P kg^?1 soil). Soil P availability indices for Mehlich 1 extractant were slightly higher at higher P rates. However, both the extracting solutions had highly significant association with grain yield.     

Potassium Requirements of Lowland Rice

Rice is a staple food for about 50 percent of the world’s population. Potassium (K) is absorbed in large amounts by rice plants and adequate amounts of this element are fundamental to improve productivity and maintain sustainability of the cropping systems. A greenhouse experiment was conducted to determine the adequate rate of K for lowland rice grown on a Brazilian Inceptisol. The K rates used were 0, 50, 100, 200, 400, and 600 mg K kg^?1 soil. Most of the growth, yield, and yield components were significantly and quadratically increased with increasing K levels. Based on a quadratic equation, maximum grain yield was obtained with the addition of 371 mg K kg^?1 soil. Maximum plant height and shoot dry weight were obtained at 414 and 398 mg K kg^?1 soil, respectively. Root growth (maximum length and dry weight) was also significantly increased in a quadratic fashion with the increasing K rate in the growth medium. Maximum root length was achieved at 58 mg K kg^?1 whereas maximum root dry weight was obtained with the addition of 394 mg K kg^?1 soil. Plant height, shoot dry weight, 1000-grain weight, root length, and root dry weight were significantly associated with grain yield. Hence, manipulation of these growth and yield components with the addition of K fertilizer can improve yield of lowland rice in varzea soils of central part of Brazil. Potassium uptake increased significantly in a quadratic fashion with increasing K rate. However, K-use efficiency (mg grain per mg K applied) decreased significantly with increasing K rate in a quadratic fashion. Maximum grain yield was obtained with 117 mg kg^?1 Mehlich 1–extractable K, base saturation of 53 percent, Mg saturation of 9 percent, K saturation of 2 percent, and Ca/Mg ratio of 4.     

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.     

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.     

Internal and External Phosphorus Requirements for Optimum Grain Yield are Associated with P-utilization Efficiency of Wheat Cultivars

ABSTRACT

Considerable variation exists among wheat cultivars for phosphorus (P) acquisition and utilization to produce higher yields. We investigated critical P requirements for optimum grain yield of two wheat cultivars contrasting in P-use efficiency, i.e., NIA-Sunder (P-efficient) and NIA-Saarang (P-inefficient). Grain yield, P accumulation, and other P-efficiency relations of both cultivars increased with progressive addition of P, but at variable rates. NIA-Sunder exhibited higher grain yield, grain P concentration, harvest index, and P-use efficiency at all P levels as compared to NIA-Saarang. Internal P requirement for achieving 95% relative grain yield in NIA-Sunder and NIA-Saarang was obtained when P concentration in their grains was 4.07 and 3.48 mg g^?1 recorded at external P levels of 57.2 and 78.1 mg kg^?1 soil, respectively. Overall, NIA-Sunder accumulated 15% more grain P and required 27% less external P for attaining 95% relative yield than P-inefficient cultivar. Results suggested that internal and external P requirements aiming at optimum grain yield are associated with genotypic variations in wheat cultivars for P-utilization efficiency.     

Influence of Lime and Gypsum on Yield and Yield Components of Soybean and Changes in Soil Chemical Properties

Soybean is one of the most important legume crops in the world. Two greenhouse experiments were conducted to determine the influence of liming and gypsum application on yield and yield components of soybean and changes in soil chemical properties of an Oxisol. Lime rates used were 0, 0.71, 1.42, 2.14, 2.85, and 4.28 g kg^?1 soil. Gypsum rates applied were 0, 0.28, 0.57, 1.14, 1.71, and 2.28 g kg^?1 soil. Lime as well as gypsum significantly increased grain yield in a quadratic fashion. Maximum grain yield was achieved with the application of 1.57 g lime per kg soil, whereas the gypsum requirement for maximum grain yield was 1.43 g per kg of soil. Lime significantly improved soil pH, exchangeable soil calcium (Ca) and magnesium (Mg) contents, base saturation, and effective cation exchange capacity (ECEC). However, lime application significantly decreased total acidity [hydrogen (H) + aluminum (Al)], zinc (Zn), and iron (Fe) contents of the soil. The decrease in these soil properties was associated with increase in soil pH. Gypsum application significantly increased exchangeable soil Ca, base saturation, and ECEC. However, gypsum did not change pH and total acidity (H + Al) significantly. Adequate soil acidity indices established for maximum grain yield with the application of lime were pH 5.5, Ca 1.8 cmol_c kg^?1, Mg 0.66 cmol_c kg^?1, base saturation 53%, Ca saturation 35%, and Mg saturation 13%. Soybean plants tolerated acidity (H + Al) up to 2.26 cmol_c kg^?1 soil. In the case of gypsum, maximum grain yield was obtained at exchangeable Ca content of 2.12 cmol_c kg^?1, base saturation of 56%, and Ca saturation of 41%.     

Liming and Copper Fertilization in Dry Bean Production on an Oxisol in No-tillage System

ABSTRACT

A field study was conducted with the objective of determining response of dry bean (Phaseolus vulgaris L.) to liming and copper (Cu) fertilization applied to an Oxisol. The lime rates used were 0, 12, and 24 Mg ha^?1 and Cu rates were 0, 2.5, 5, 10, 20, and 40 kg Cu ha^?1. Liming significantly increased common bean grain yield. Liming also significantly influenced soil chemical properties in the top (0–10 cm) as well as in the sub (10–20 cm) soil layer in favor of higher bean yield. Application of Cu did not influence yield of bean significantly. Average soil chemical properties across two soil layers (0–10 and 10–20 cm) for maximum bean yield were pH 6.4, calcium (Ca), 4.2 cmol_c kg^?1, magnesium (Mg) 1.0 cmol_c kg^?1, H+Al 3.2 cmol_c kg^?1, acidity saturation 40.4%, cation exchange capacity (CEC) 8.9 cmol_c kg^?1, base saturation 63.1%, Ca saturation 45.7%, Mg saturation 18.0%, and Potassium (K) saturation 2.9.     

Yield and Yield Components of Dry Bean Genotypes as Influenced by Phosphorus Fertilization

Dry bean is an important legume for South American population, and phosphorus (P) deficiency is the most yield-limiting nutrient for crop production in South American soils. A greenhouse experiment was conducted with the objective of evaluating influence of P fertilization on grain yield and yield components of 30 dry bean genotypes. The P levels used were 0 mg P kg^?1 (natural level of the soil) and 200 mg P kg^?1 applied with triple superphosphate fertilizer. Yield and yield components were significantly influenced with P as well as genotype treatments. The P?×?genotype interactions were significant for yield as well as yield components, indicating different responses of genotypes at two P levels. Root dry weight and maximum root length were also significantly increased with the addition of P fertilization. There were also significant differences among the genotypes in the growth of root system. Based on grain yield efficiency index (GYEI), genotypes were classified as P efficient, moderately efficient, and inefficient. Among 30 genotypes, 17 were classified as efficient, 12 were classified as moderately efficient, and 1 was classified as inefficient. Yield components such as pods per plant and seeds per pod were having significant positive association with grain yield. In addition, grain harvest index (GHI) was also having significant linear association with grain yield. Hence, it is possible to improve grain yield of dry bean in Brazilian Oxisol with the addition of adequate rate of P fertilization as well as use of P-efficient genotypes.