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.     

Fifteen-year fallow altered the dynamics of soil phosphorus and cationic balance of a savannah Alfisol

This study was designed to evaluate changes in the dynamics of soil phosphorus and cationic balances of a savannah soil subjected to 45 years of continuous cultivation under different fertilizer management and later left fallow for 15 years. It was conducted on the experimental plots at the Institute for Agricultural Research, Ahmadu Bello University, Nigeria. Treatments consisted of nitrogen (N), phosphorus (P), potassium (K), cow dung manure (D) and their combination (DNPK). Results of P fractionation and cationic distribution were compared with previous studies on the same plot 15 years ago. Organic carbon increased from a range of 3–5 g kg^?1 in 1997 to 10.9 g kg^?1 in 2012. Similarly, the cation exchange capacity (CEC) of the soil increased from 6.40 cmol_c kg^?1 in 1997 to 16.4 cmol_c kg¹ in the present study. The degree of saturation of the CEC by Ca²⁺ was 68–79% and 10–20% for Mg²⁺, while that of K⁺ was 1.5–2%. Although there was an uneven trend in depletion and enrichment of the various P pools, however, the fallow period substantially improved the CEC and the plant available P pools of the soil by more than 200% and 6–259%, respectively.     

Ammonia toxicity in aerobic rice: use of soil properties to predict ammonia volatilization following urea application and the adverse effects on germination

Recent studies indicate that aerobic rice can suffer injury from ammonia toxicity when urea is applied at seeding. Urea application rate and soil properties influence the accumulation of ammonia in the vicinity of recently sown seeds and hence influence the risk of ammonia toxicity. The objectives of this study were to (i) evaluate the effects of urea rate on ammonia volatilization and subsequent seed germination for a range of soils, (ii) establish a critical level for ammonia toxicity in germinating rice seeds and (iii) assess how variation in soil properties influences ammonia accumulation. Volatilized ammonia and seed germination were measured in two micro‐diffusion incubations using 15 soils to which urea was applied at five rates (0, 0.25, 0.5, 0.75 and 1.0 g N kg^?1 soil). Progressively larger urea rates increased volatilization, decreased germination and indicated a critical level for ammonia toxicity of approximately 7 mg N kg^?1. Stepwise regression of the first three principal components indicated that the initial pH and soil texture components influenced ammonia volatilization when no N was added. At the intermediate N rate all three components (initial pH, soil texture and pH buffering) affected ammonia volatilization. At the largest N rate, ammonia volatilization was driven by soil texture and pH buffering while the role of initial pH was insignificant. For soils with an initial pH > 6.0 the risk of excessive volatilization increased dramatically when clay content was <150 mg kg^?1, cation exchange capacity (CEC) was <10 cmol_c kg^?1 and the buffer capacity (BC) was <2.5 cmol_c kg^?1 pH^?1. These findings suggest that initial pH, CEC, soil texture and BC should all be used to assess the site‐specific risks of urea‐induced ammonia toxicity in aerobic rice.     

Influence of long-term application of composted or stockpiled feedlot manure with straw or wood chips on soil cation exchange capacity

The influence of annual applications of composted (CM) or stockpiled (SM) beef feedlot manure with straw (ST) or wood-chip (WD) bedding on cation exchange capacity (CEC) of a clay loam soil in southern Alberta was examined after 1, 8, and 15 years. The hypotheses in our study were that soil CEC should be greater for amended than unamended soils; manure type and bedding should have no effect on soil CEC; and soil CEC should increase with greater manure application rate. After fifteen applications, the CEC was significantly greater for amended than unamended soils. Manure type had no significant (P > 0.05) effect on soil CEC after fifteen applications, and the mean soil CEC was 5% greater for WD than ST. Mean CEC was significantly greater by 7 to 12% for the 77 than the 13 and the 39 Mg ha^?1 rates after fifteen applications. The soil CEC was increased by 0.061 cmol_c kg^?1 for a unit increase in application rate (Mg dry wt. ha^?1 yr^?1), and 96% of the variation in CEC for amended soils could be explained by application rate. Overall, bedding, rate, or adjusting both bedding type and manure rate (but not manure type), may be possible practices for feedlot producers to manage soil CEC.     

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.     

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%.     

施用生物肥料，镁石灰石，玄武岩可改善马来西亚酸性硫酸盐土壤化学性质与水稻生长状况

Acid sulfate soils are normally not suitable for crop production unless they are appropriately ameliorated. An experiment was conducted in a glasshouse to enhance the growth of rice, variety MR219, planted on an acid sulfate soil using various soil amendments.The soil was collected from Semerak, Kelantan, Malaysia. Ground magnesium limestone（GML）, bio-fertilizer, and basalt（each 4t ha^-1） were added either alone or in combinations into the soil in pots 15 d before transplanting. Nitrogen, P and potash were applied at 150, 30, and 60 kg ha^-1, respectively. Three seven-day-old rice seedlings were transplanted into each pot. The soil had a p H of 3.8 and contained organic C of 21 g kg^-1, N of 1.2 g kg^-1, available P of 192 mg kg^-1, exchangeable K of 0.05 cmolc kg^-1,and exchangeable Al of 4.30 cmol c kg^-1, with low amounts of exchangeable Ca and Mg（0.60 and 0.70 cmol c kg^-1）. Bio-fertilizer treatment in combination with GML resulted in the highest p H of 5.4. The presence of high Al or Fe concentrations in the control soil without amendment severely affected the growth of rice. At 60 d of growth, higher plant heights, tiller numbers and leaf chlorophyll contents were obtained when the bio-fertilizer was applied individually or in combination with GML compared to the control. The presence of beneficial bacteria in bio-fertilizer might produce phytohormones and organic acids that could enhance plant growth and subsequently increase nutrient uptake by rice. Hence, it can be concluded that addition of bio-fertilizer and GML improved rice growth by increasing soil pH which consequently eliminated Al and/or Fe toxicity prevalent in the acid sulfate soil.     

Effect of biochar amendment on soil physical,chemical and biological properties and groundnut yield in rainfed Alfisol of semi-arid tropics

The aim of this study was to evaluate the effect of biochar and organic soil amendments on soil physicochemical and microbial load, carbon sequestration potential, nutrient uptake and yield of groundnut in acidic red soil under rainfed condition. Biochar was prepared from red gram, cotton, maize stalk and mesquite wood using pilot scale slow pyrolysis biochar unit. The above sources of biochar at the rate of 2.5 and 5 t ha^?1 and enriched farmyard manure 0.75 t ha^?1, composted coir pith 10 t ha^?1 and arbuscular mycorrhizae 100 kg ha^?1 were applied as basal with required nitrogen, phosphorous and potassium fertilizer. Biochar amendment at the rate of 5 t ha^?1 reduced the bulk density from 1.41 to 1.36 g cm^?3 and increased the soil moisture 2.5%. With respect to soil chemical changes, it raised soil pH from 5.7 to 6.3; increased the cation exchange capacity 1.4 cmol⁺ kg^?1 and enhanced the carbon buildup 4.4 t ha^?1. The significant differences in bacteria, fungi and actinomycetes population were observed between biochar and control. The nitrogen, phosphorous and potassium were better utilized under biochar and composted coir pith, which was 21, 5 and 20 kg ha^?1 higher than control. The experimental results suggested that application of biochar to acidic red soil favoured good soil physical, chemical and biological environment, and these positive changes influenced growth and yield attributes and enhanced pod yield 29% over control.     

Effects of green manure and coral lime on corn growth and chemical properties of an acid Oxisol in Western Samoa

Effects of local green manure (GM) and lime on soil productivity in a low-input agricultural system were evaluated by growing three successive crops of sweet corn (Zea mays) on an acid Oxisol (Typic acrorthox, Togitogiga series) in Western Samoa. The soil was amended with coral lime at 0, 5, and 10Mgha^–1 and with cowpea GM at 0, 7.5, and 15Mgha^–1. Commercial NPK fertilizers at 50kgha^–1 each of N, P, and K were included for comparison. The amendments were applied only once prior to planting of the first crop. Response parameters measured included nutrient composition of leaves at tasseling and grain yield of each crop, and selected soil chemical properties at each planting. Yields of the first crop were nearly tripled with GM additions and doubled with lime additions. Such yield increases were caused mainly by better K nutrition and to a lesser extent by enhanced P nutrition. Yields of subsequent crops were much lower than those of the first, and the declines were much steeper for the GM treatments than for the lime treatments. Thus, the enhancement effect on K nutrition did not last beyond one crop. Poor growth of the second and third crops was caused by K deficiency; probably coupled with Mn toxicity. Significant yield reductions were found when Mn-to-K ratios in leaves exceeded 0.010. As for effects on soil, soil pH was increased significantly by lime but only slightly by GM. Given the variable charge property of this Oxisol, each unit pH increase corresponds to a cation exchange capacity (CEC) increase of 5cmol_ckg^–1. Having greater CEC, the amended soil retained K more effectively, thereby causing yield increases, especially of the first corn crop, which required at least 0.75cmol_ckg^–1 of exchangeable soil K or 7% of CEC for adequate growth. Received: 15 April 1996     

Correcting soil acidity of a highly weathered Ultisol with chicken manure and sewage sludge

Abstract

The seriousness of soil acidity and the unavailability of “conventional”; liming materials in many developing countries necessitate a search for alternatives. With this goal in mind, the liming potential of two organic manures was investigated. The investigation was conducted in the greenhouse, using a highly weathered, acid Ultisol. Application rates were 0, 5, 10, 20, and 40 g kg^‐1 for chicken manure and 20 g kg^‐1 for sewage sludge. Treatments of Ca(OH)₂ at 2, 4, 6, and 8 cmol_ckg^‐1, were included for comparison.

Based on growth response of Desmodium intortum, a tropical forage legume with a relatively high Ca requirement and low Al tolerance, it was demonstrated that soil acidity can be corrected by either Ca(OH)₂ or organic manure additions. Both lime and manures raised soil pH and inactivated Al. In terms of pH increases, 5 and 10 g chicken manure kg^‐1 were equivalent to 3.4 and 6.7 cmol_ckg^‐1; and 20 g sludge kg^‐1, equivalent to 6.5 cmol_ckg^‐1 as Ca(OH)₂. The manures also detoxified soluble Al by organic complexation and enhanced Ca uptake of the Desmodium. The plant's maximum growth required at least 1.0% Ca in leaves, and this growth was reduced by half when leaf Al ≥ 76 mg kg^‐1 and soil‐solution Al³⁺ activity ≥ 4 μM.     

Cation exchange capacities of organo-mineral particle-size fractions in soils from long-term experiments

Soils with and without organic manuring from 10 long-term manurial experiments in East Germany were fractionated into organo-mineral particle-size separates by ultrasonic disaggregation and sedimentation/decantation. The cation exchange capacities (CECs) buffered at pH 8.1 were determined for the size fractions fine+medium clay, coarse clay, fine, medium and coarse silt, sand, and for the total soil samples. In the samples from nine field experiments the CECs decreased with increased equivalent diameters (fine+medium clay: 489–8 13 mmol_c kg^?1, coarse clay: 367–749 mmol_c kg^?1, fine silt: 202–587 mmol_c kg^?1. medium silt: 63–345 mmol_c kg^?1, coarse silt: 12–128 mmol_c kg^?1 and sand: 10–156 mmol_c kg^?1. The CECs varied with genetic soil type, mineralogical composition of the <6.3-μm particles, and the C and N contents of the size fractions. In a pot experiment examining the role of various organic materials in the early stages of soil formation, the clay-size fractions had the largest CECs (85–392 mmol_c kg^?1), followed by the medium-silt (1 9-222 mmol_c kg^?1) and fine-silt fractions (23–192 mmol_c kg^?1). The effect of organic amendments on CEC was in general: compost>fresh farmyard manure = straw + mineral fertilizer = mineral fertilizer.     

Influence of Lime and Gypsum on Growth and Yield of Upland Rice and Changes in Soil Chemical Properties

Upland rice is an important crop in the cropping systems of South America, including Brazil. Two greenhouse experiments were conducted to determine influence of lime and gypsum on yield and yield components of upland rice and changes in the chemical properties of an Oxisol. The lime rates used were 0, 0.71, 1.42, 2.14, 2.85, and 4.28 g kg^?1 soil. The gypsum rates were 0, 0.28, 0.57, 1.14, 1.71, and 2.28 g kg^?1. Lime as well as gypsum significantly increased plant height, straw and grain yield, and panicle density in a quadratic fashion. Adequate lime and gypsum rates for maximum grain yield were 1.11 g kg^?1 and 1.13 g kg^?1, respectively. Plant height, straw yield, and panicle density were positively related to grain yield. Lime as well as gypsum application significantly changed extractable calcium (Ca), magnesium (Mg), hydrogen (H)+aluminum (Al), base saturation, and effective cation exchange capacity. In addition, liming also significantly increased pH, extractable phosphorus (P) and potassium (K), calcium saturation, magnesium saturation, and potassium saturation. Optimum acidity indices for the grain yield of upland rice were pH 6.0, Ca 1.7 cmol_c kg^?1, base saturation 60%, and calcium saturation 47%. In addition, upland rice can tolerate 42% of acidity saturation.     

Effects of Soil Amendments on Growth and Metal Uptake by Ocimum gratissimum Grown in Cd/Zn-Contaminated Soil

Hydroponic and pot experiments were conducted to assess the uptake of heavy metals (Cd and Zn) by a common crop plant, African basil, Ocimum gratissimum. In addition, the effects of soil amendments, hydroxyapatite (HA) and cow manure on plant growth and metal accumulations were compared. In the hydroponic study, plants were exposed to various concentrations of Cd (2.5 and 5 mg L^?1) and Zn (10 and 20 mg L^?1) for 15 days. O. gratissimum was shown to be a Cd accumulator more than a Zn accumulator. Cadmium concentration in its shoots exceeded 100 mg kg^?1. In the pot experiments, soils from a heavily Cd-contaminated site (Cd 67.9 mg kg^?1 and Zn 2,886.8 mg kg^?1) were treated with cow manure and HA at the rates of 10% and 20% (w/w), and 0.75 and 1.5% (w/w), respectively. Plants were grown in the greenhouse for 3 months. The addition of cow manure resulted in the highest biomass production and the lowest accumulations of Cd in plant parts, while HA was more efficient than cow manure in reducing Zn uptake. Leaves of African basil showed a decreased Cd concentration from 1.5 to 0.3 mg kg^?1 (cow manure) and decreased Zn concentration from 69.3 to 34 mg kg^?1 (HA). This clearly demonstrates the efficiency of HA and cow manure in reducing metal content in leaves of plants grown on high metal-contaminated soil to acceptable or close to acceptable values (0.2 mg kg^?1 for Cd, 99.4 mg kg^?1 for Zn).     

Yield,Nutrient Uptake,and Changes in Soil Chemical Properties as Influenced by Liming and Iron 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 pH_w 6.3, Ca²⁺ 3.8 cmol_c kg^–1, Mg²⁺ 1.1 cmol_c kg^–1, 3.5 H⁺ + Al³⁺ cmol_c kg^–1, acidity saturation 41.8%, CEC 7.5 cmol_c 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.     

Effect of Sheep Manure and Its Produced Vermicompost and Biochar on the Properties of a Calcareous Soil after Barley Harvest

ABSTRACT

Conversion of manures to vermicompost and biochar may alleviate some negative effects of manure application to soil but the efficiency of the produced vermicompost and biochar as compared to their feedstocks is not well-known. In the current investigation, we compared the effects of sheep manure and its derived vermicompost and biochar (pyrolyzed at 400°C for 4 h) on the properties of a calcareous soil that planted with five cultivars of barley (Behrokh, Khatam, Reyhaneh03, Fajr 30 and Nimrooz) for 60 days. Different soil properties and availability of nutrients and barley yield were determined after plant harvest. The biochar significantly increased barley yield rather than control (4.20 vs. 3.57 g pot^?1), but sheep manure and vermicompost had no effect on it (3.51 and 3.37 g pot^?1, respectively). Fajr 30 and Nimrooz (3.52 and 3.42 g pot^?1, respectively) had significantly lower yield than other cultivars. Biochar increased soil pH up to 8.2. Soil salinity was increased by application of all organic materials (increase to 16–36%). Cation exchange capacity (CEC) and organic matter content of soil were also increased by all organic materials application (0.4–0.9 cmol kg^?1 and 0.33–0.50%, respectively). All organic materials increased total nitrogen (N), but this increase was the highest with sheep manure application (53%). The availability of phosphorus (P) and potassium (K) was increased significantly by application of all organic materials, and this increase was the highest with biochar application (19 and 309 mg kg^?1, respectively). Biochar application had no effect on the availability of micronutrients, but application of sheep manure and vermicompost increased the availability of iron (Fe) (0.62 and 0.48 mg kg^?1, respectively) and zinc (Zn) (0.18 and 0.37 mg kg^?1, respectively). Generally, organic materials may change the status of soil nutrients via change in soil pH, organic matter content, release of nutrients, increase in soil CEC and formation of soluble complex with nutrients.     

Low Pyrolysis Temperature Biochar Improves Growth and Nutrient Availability of Maize on Typic Calciargid

This experiment was conducted to investigate the effects of biochars, produced from maize straw at different temperatures (300, 400, and 500 °C), on growth of maize. Maximum cation exchange capacity (CEC) (106 cmol_c kg^?1) of biochar was observed at 400 °C. The pH, electrical conductivity (EC), and carbon content of biochars significantly increased with increasing temperature, and maximum pH (9.8), EC (3.0 dS m^?1), and carbon content (607 g kg^?1) were observed at 500 °C. Concentration of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) significantly increased with increasing temperature, while of nitrogen (N) decreased. Ammonium bicarbonate–diethylene triamine penta acetic acid (AB-DTPA)–extractable nutrients were decreased with increasing pyrolysis temperature. Shoot and root dry matter of maize increased significantly with application of biochar produced at 300 and 400 °C and decreased significantly at 500 °C. Maximum shoot and root dry matter of maize was obtained at biochar produced at 300 °C. Phosphorus and K concentration in shoots and roots increased with biochar, and it was significantly more with fertilizer application. In contrast to P, shoot and root K concentration increased significantly with increasing pyrolysis temperature. The results of this study indicated that application of biochar produced at low pyrolysis temperature may be a practical approach to improve crop growth.     

Unlocking fixed soil phosphorus upon waterlogging can be promoted by increasing soil cation exchange capacity

Phosphorus (P) adsorbed by iron (Fe) oxyhydroxides in soil can be released when the Fe(III) minerals are reductively dissolved after soil flooding. However, this release is limited in tropical soils with large Fe contents and previous studies have suggested that P sorbs or precipitates with newly formed Fe(II) minerals. This hypothesis is tested here by scavenging Fe²⁺ in flooded soils by increasing the cation exchange capacity (CEC) of soil through resin application (30 cmol_c kg^?1; Na‐form). Three soils from rice paddies with contrasting properties were incubated in aerobic and anaerobic conditions with or without resin and with or without addition of organic matter (OM) to stimulate redox reactions. Dissolved Fe was 0.1–1.1 mm in unamended anaerobic soils and decreased to less than 0.07 mm with resin addition. Anaerobic soils without resin and aerobic soils with or without resin had marginal available P concentrations (<2 mg P kg^?1; anion‐exchange membrane P). In contrast, available P increased 3‐ to 14‐fold in anaerobic soils treated with resins, reaching 16 mg P kg^?1 in combination with extra OM. Application of Ca‐forms of resin did not stimulate P availability and dissolved Ca concentrations were larger than in unamended soils. Resin addition can increase P availability, probably by a combination of reducing solution Fe²⁺ (thereby limiting the formation of Fe(II) minerals) and increasing the OM solubility and availability through reducing dissolved Ca²⁺. The soil CEC is a factor controlling the net P release in submerged soils.     

Interaction study of biochar with phosphate-solubilizing bacterium on phosphorus availability in calcareous soil

A large proportion of phosphate fertilizer applied to calcareous soils reacts with calcium. Changes in soil phosphorus (P) availability after single application of biochar and phosphate-solubilizing bacteria have been reported. However, interaction of biochar (increasing soil pH) and phosphate-solubilizing bacteria (decreasing soil pH) on P availability in calcareous soil is not well known. An incubation experiment was conducted to study how the interactive effects of biochars (produced from wheat straw and cow manure at 300°C and 500°C with residence time of 1, 3 and 6 h) at different rates (0, 5 and 10 t ha^?1) and phosphate-solubilizing Pseudomonas sp. IS8b2 affected on content of soil available P after 0, 60, 120 and 180 days of incubation (DOI) in a calcareous soil. After 60 DOI, the maximum value of available P (50.31 mg kg^?1) was observed in the compound treatment of Pseudomonas sp. IS8b2 and wheat straw biochar (10 t ha^?1) produced at 500°C with residence time of 3 h. We conclude that the combination use of wheat straw biochar and phosphate-solubilizing bacterium is promising to potentially improve soil P availability in calcareous soil, but further research at field scale is needed to confirm this.     

Coffee‐husk biochar application increased AMF root colonization,P accumulation,N2 fixation,and yield of soybean grown in a tropical Nitisol,southwest Ethiopia

Low soil fertility and soil acidity are among the major bottlenecks that limit agricultural productivity in the humid tropics. Soil management systems that enhance soil fertility and biological cycling of nutrients are crucial to sustain soil productivity. This study was, therefore, conducted to determine the effects of coffee‐husk biochar (0, 2.7, 5.4, and 16.2 g biochar kg^?1 soil), rhizobium inoculation (with and without), and P fertilizer application (0 and 9 mg P kg^?1 soil) on arbuscular mycorrhyzal fungi (AMF) root colonization, yield, P accumulation, and N₂ fixation of soybean [Glycine max (L.) Merrill cv. Clark 63‐K] grown in a tropical Nitisol in Ethiopia. ANOVA showed that integrated application of biochar and P fertilizer significantly improved soil chemical properties, P accumulation, and seed yield. Compared to the seed yield of the control (without inoculation, P, and biochar), inoculation, together with 9 and 16.2 g biochar kg^?1 soil gave more than two‐fold increment of seed yield and the highest total P accumulation (4.5 g plant^?1). However, the highest AMF root colonization (80%) was obtained at 16.2 g biochar kg^?1 soil without P and declined with application of 9 mg P kg^?1 soil. The highest total N content (4.2 g plant^?1) and N₂ fixed (4.6 g plant^?1) were obtained with inoculation, 9 mg P kg^?1, and 16.2 g biochar kg^?1 soil. However, the highest %N derived from the atmosphere (%Ndfa) (> 98%) did not significantly change between 5.4 and 16.2 g kg^?1 soil biochar treatments at each level of inoculation and P addition. The improved soil chemical properties, seed yield, P accumulation and N₂ fixation through combined use of biochar and P fertilizer suggest the importance of integrated use of biochar with P fertilizer to ensure that soybean crops are adequately supplied with P for nodulation and N₂‐fixation in tropical acid soils for sustainable soybean production in the long term.     

Yield,Nutrient Uptake,and Soil Chemical Properties as Influenced by Liming and Boron Application in Common Bean in a No‐Tillage System

Abstract

In Oxisols, acidity is the principal limiting factor for crop production. In recent years, because of intensive cropping on these soils, deficiency of micronutrients is increasing. A field experiment was conducted on an Oxisol during three consecutive years to assess the response of common bean (Phaseolus vulgaris L.) under a no‐tillage system to varying rates of lime (0, 12, and 24 Mg ha^?1) and boron (0, 2, 4, 8, 12, 16, and 24 kg ha^?1) application. Both time and boron (B) were applied as broadcast and incorporated into the soil at the beginning of the study. Changes in selected soil chemical properties in the soil profile (0- to 10‐ and 10- to 20‐cm depths) with liming were also determined. During all three years, gain yields increased significantly with the application of lime. However, B application significantly increased common bean yield in only the first crop. Only lime application significantly affected the soil chemical properties [pH; calcium (Ca²⁺); magnesium (Mg²⁺); hydrogen (H⁺)+ aluminum (Al³⁺); base saturation; acidity saturation; cation exchange capacity (CEC); percent saturation of Ca²⁺, Mg²⁺, and potassium (K⁺); and ratios of exchangeable Ca/Mg, Ca/K, and Mg/K] at both soil depths (0–10 cm and 10–20 cm). A positive significant association was observed between grain yield and soil chemical properties. Averaged across two depths and three crops, common bean produced maximum grain yield at soil pH_w of 6.7, exchangeable (cmol_c kg^?1) of Ca²⁺ 4.9, Mg²⁺ 2.2, H⁺+Al³⁺ 2.6, acidity saturation of 27.6%, CEC of 4.1 cmol_c kg^?1, base saturation of 72%, Ca saturation of 53.2%, Mg saturation of 17.6%, K saturation of 2.7%, Ca/Mg ratio of 2.8, Ca/K ratio of 25.7, and Mg/K ratio of 8.6. Soil organic matter did not change significantly with addition of lime.