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.     

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.     

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.     

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%.     

Low nitrogen availability and shallow plow layer decrease sugarcane (Saccharum officinarum L.) productivity in Kitadaito Island,Japan

Sugarcane is the main crop in Kitadaito Island, Okinawa, Japan. The average yield in Kitadaito Island for the past 30 years (1985–2015) was 44 Mg ha^?1, 31% lower than that (64 Mg ha^?1) in Okinawa Prefecture. Among the reasons for the low sugarcane productivity in Kitadaito Island, the effects of soil and cultivation factors have not been sufficiently studied. The objectives of this study were i) to evaluate the effects of soil physical and chemical properties and cultivation factors on sugarcane yield and sugar content in 50 fields of Kitadaito Island, and ii) to clarify factors affecting the sugarcane yield and sugar content. Statistical analysis of classification and regression trees (CART) showed that the sugarcane yield was low in fields with low available nitrogen (less than 16.5 mg kg^?1) and with shallow plow layer depth (less than 29 cm). The soil available nitrogen had a significant positive correlation with soil humus (r = 0.39, P < 0.05). Two-times of subsoiling in the field before planting and during growing periods resulted in the significant increase of the depth of plow layer, compared to the fields with single and no subsoiling. A high sugar content was obtained in fields with exchangeable Mg more than 3.8 cmol_c kg^?1 and pH(H₂O) less than 7.2. Our study therefore concluded that soil management practices for sugarcane production in Kitadaito Island should primarily be focused on available nitrogen, plow layer depth, and soil exchangeable Mg and pH.     

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.     

Differential Soil Acidity Tolerance of Tropical Legume Cover Crops

In tropical regions, soil acidity and low soil fertility are the most important yield‐limiting factors for sustainable crop production. Using legume cover crops as mulch is an important strategy not only to protect the soil loss from erosion but also to ameliorate soil fertility. Information is limited regarding tolerances of tropical legume cover crops to acid soils. A greenhouse experiment was conducted to determine the differential tolerance of 14 tropical legume cover crops to soil acidity. The acidity treatments were high (0 g lime kg^?1 soil), medium (3.3 g lime kg^?1 soil), and low (8.3 g lime kg^?1 soil). Shoot dry weight of cover crops were significantly affected by acidity treatments. Maximum shoot dry weight was produced at high acidity. Jack bean, black mucuna, and gray mucuna bean species were most tolerant to soil acidity, whereas Brazilian lucern and tropical kudzu were most susceptible to soil acidity. Overall, optimal soil acidity indices were pH 5.5, hydrogen (H)+ aluminum (Al) 6.8 cmol_c kg^?1, base saturation 25%, and acidity saturation 74.7%. Species with higher seed weight had higher tolerance to soil acidity than those with lower seed weight. Hence, seed weight was associated with acidity tolerance in tropical legume species.     

Optimum Soil Acidity Indices for Dry Bean Production on an Oxisol in No‐Tillage System

Abstract

Soil acidity is one of the major yield constraints to crop production in various parts of the world. Quantifying optimum soil acidity indices is an important strategy for achieving maximum economic crop yields on acid soils. Five field experiments were conducted for three consecutive years using dry bean as a test crop on an Oxisol. The lime rates used were 0, 12, and 24 Mg ha^?1 for creating a wide range of soil acidity indices in a no‐tillage cropping system. Grain yield of dry bean was significantly increased by improving soil pH, base saturation, calcium (Ca), magnesium (Mg), and potassium (K) saturation and reducing aluminum (Al) saturation. These soil acidity indices were higher in the 0‐ to 10‐cm soil layer than the 10‐ to 20‐cm soil layer for maximum grain yield. Across two soil depths, optimum values for maximum bean yield were pH 6.5, base saturation 67%, Ca saturation 48%, and Mg saturation 19%. Bean yield linearly increased with increasing K saturation in the range of 1.5 to 3% across two soil depths. There was a significant linear decrease in grain yield with increasing Al saturation in the range of 0 to 8% across two soil depths. Optimal values of soil indices for maximum bean yield can be used as a reference for liming and improving yield of bean crop on Oxisols in a no‐tillage cropping system. Yield components, such as pod number, grain per pod, and 100‐grain weight were significantly improved with liming, and bean yield was significantly associated with these yield components.     

Plant Availability Index by Potassium Exchange Isotherms in Selected Rice Soils of Lesser Himalayas

Potassium (K) exchange isotherms (quantity–intensity technique, Q/I) and K values derived from the Q/I relationship provide information about soil K availability. This investigation was conducted to study Q/I parameters of K, available K extracted by 1 N ammonium acetate (NH₄AOc) (exchangeable K plus solution K), K saturation percentage (K index, %), and the properties of 10 different agricultural soils. In addition, the relationship of mustard plant yield response to the K requirement test based on K exchange isotherms was investigated. The Q/I parameters included readily exchangeable K (ΔK₀), specific K sites (K_X), linear potential buffering capacity (PBC^K), and energy of exchange of K (E_K). The results of x-ray diffraction analysis of the oriented clay fractions indicated that some mixed clay minerals, illite clay minerals, along with chlorite/hydroxy interlayered vermiculite and kaolinite were present in the soils. The soil solution K activity ratio at equilibrium (AR₀) ranged from 8.0 × 10^?4 to 3.1 × 10^?3 (mol L^?1)^0.5. The readily exchangeable K (ΔK₀) was between 0.105 to 0.325 cmol_ckg^?1 soil, which represented an average of 88% of the exchangeable K (K_ex). The soils showed high capacities to maintain the potential of K against depletion, as they represented high linear potential buffering capacities (PBC^K) [13.8 to 50.1 cmol_c kg^?1/(mol L^?1)^0.5. The E_K values for the soils ranged from ?3420 to ?4220 calories M^?1. The percentage of K saturation (K index) ranged from 0.7% to 2.2%. Analysis of variance of the dry matter (DM), K concentrations, and K uptake of mustard plants indicated that there were no significant differences among the adjusted levels of K as determined by the exchange-isotherm curve.     

Rice and common bean growth and nutrient concentration as influenced by aluminum on an acid lowland soil

Aluminum (Al) toxicity is a major limiting factor for crop production in many acid soils in Brazil. Two greenhouse experiments were conducted to evaluate response of rice (Oryza saliva L.) and common bean (Phaseolus vulgaris L.) to Al levels on a Low Humic Gley acid soil. The Al levels created by liming were: 0,0.03, 0.10, 0.23, 1.03, and 3.83 cmol_c kg^‐1 of soil. Rice dry matter and grain yield were significantly improved (P<0.05) with increasing Al levels in the soil solution. However, common bean dry matter as well as grain yield were significantly (P<0.01) decreased with increasing Al levels. At 3.83 cmol_c Al kg^‐1 of soil, bean did not produce any dry matter or grain yield. On an average, Al decreased nutrient concentrations in the tops of rice plant except zinc (Zn) and manganese (Mn), but in bean crop almost all the nutrients concentrations were increased with increasing Al levels. Rice showed tolerance to Al toxicity, whereas, common bean was susceptible to toxicity of this element. For successful intensive crops production lime application will be necessary in Varzea soils especially for legume production.     

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.     

Effect of conjoint use of bio-organics and chemical fertilizers on yield,soil properties under French bean–cauliflower-based cropping system

This study investigates the effect of conjoint use of bio-organics (biofertilizers + crop residues + FYM) and chemical fertilizers on yield, physical–chemical and microbial properties of soil in a ‘French bean–cauliflower’-based cropping system of mid hills of the north-western Himalayan Region (NWHR) of India. Conjoint bio-organics at varied levels of NPK chemical fertilizers increased yield of ‘cauliflower’ over corresponding single application. Incorporation of crop residues with 75% of the recommended NPK application resulted in the highest yield (19 t ha^?1). Conjoint use of bio-organics produced a yield (15.65 t ha^?1), which was statistically on a par with 75% of the recommended NPK application alone. This indicated a saving of 75% NPK chemical fertilizers. In the case of ‘French bean’, the effect was non-significant. The results also showed significant higher soil available N (351.3 kg ha^?1) under 75% NPK + biofertilizers, whereas the highest soil available K (268.3 kg ha^?1) was recorded under 75% NPK + crop residues. Lowest bulk density (1.03 Mg m^?3), highest water holding capacity (36.5%), soil organic matter (10.6 g kg^?1), bacterial (4.13 × 10⁷ cfu g^?1) and fungal (6.3 × 10⁷ cfu g^?1) counts were recorded under sole application of bio-organics. According to our study, we concluded that the combination of NPK fertilizers and bio-organics increased yield except French bean, soil available N, K and saved chemical fertilizers under ‘French bean–cauliflower’-based cropping system.     

Sorption and transport of metals in preferential flow paths and soil matrix after the addition of wood ash

As a consequence of heterogeneous transport in soils, only a small part of the soil might be responsible for sorbing incoming elements. After staining preferential flow paths in forested Dystric Cambisol with a colour dye, we sampled soil material from the flow paths and from the soil matrix. We measured chemical properties and sorption isotherms of these two flow regions and estimated the significance of preferential flow paths for the transport of solutes leached from wood ash applied at the surface. In the A horizon (0–9 cm depth), the cation exchange capacity of the flow paths was 83.8 mmol_c kg^?1, while that of the soil matrix was only 74.6 mmol_c kg^?1. The base saturation was 42% and soil organic matter content was 41% larger in flow paths than in the soil matrix. The sorption capacity for Cu was also larger than in the matrix, whereas the sorption capacity for Sr was similar in both flow regions. The impact of the addition of 8 t wood ash ha^?1 on soil chemical properties was restricted mainly to the flow paths in the uppermost 20 cm of the soil; it was negligible in the matrix and at greater depths. Concentrations of exchangeable Ca in the flow paths increased nearly 10‐fold during the 6 months following the addition of the wood ash, and those of organically bound Pb by 50%. The opposite effect was found for exchangeable Al. Our results show that only part of the whole soil volume, approximately 50% of 0–20 cm in our study, is involved in transporting and sorbing the elements applied with the wood ash or as tracers. Such differences must be considered when calculating the maximal impact of any addition of fertilizer, wood ash, or liming agent.     

Potassium fertilization on sandy soils in relation to soil test,crop yield and K-leaching

To study the influence of potassium (K) fertilizer rate on soil test K values, crop yield, and K-leaching in sandy soils, four long-term fertilizer experiments (0–60–120–180 kg K ha^?1 a^?1) were initiated in 1988 in northern Germany on farmers fields. Clay content of the plow layer was about 4%, and organic matter between 2% and 5%. Plant available soil K was estimated with the double lactate (DL) method. Small grain cereals (rye and barley) did not respond to K fertilization in the 7-year period even though the soil test value of the K-0 plots decreased from ca. 90 to ca. 30 mg K_DL kg^?1 within 3 years. This value remained almost constant thereafter. Crop removal (including straw) of 75 kg K ha^?1 a^?1 was therefore apparently supplied from nonexchangeable K fractions. Compared to the optimum, no K application reduced the yield of potato by up to 21%, and that of white sugar yield up to 10%. Maximum potato yield was obtained by annually applying 60 kg K ha^?1 which resulted in a test value of 60 mg K_DL kg^?1 soil. Maximum potato yield was also obtained at 40 mg K_DL kg^?1 soil, however, with a single application of 200 kg K ha^?1. Similar results were obtained with sugar beet. This indicates that for maximum yield, even for K demanding crops, it is not necessary to maintain K_DL values above 40 mg K kg^?1 soil throughout the entire crop rotation. Soil test values increased roughly proportional to the K fertilizer level. About 120 kg fertilizer K ha^?1 a^?1, markedly more than crop K removal, was required to maintain the initial K_DL of 90 mg kg^?1. The K concentration of the soil solution in the top soil measured after harvest was increased exponentially by K fertilizer level and so was K leaching from the plow layer into the rooted subsoil. The leached quantity increased from 22 kg K ha_?1 a_?1 in the plot without K application to 42.79 and 133 kg Kha^?1 a^?1 in plots supplied with 60, 120 and 180 kg K ha^?1 a^?1 respectively. Soil test values around 100 mg K_DL kg^?1 on sandy soils, as often found in the plow layer of farmers fields, lead to K leaching below the root zone that may exceed the critical K concentration of 12 mg K T^?1 for drinking water.     

Effects of Liming and Fertilization (N,PK) on Chemistry and Nitrogen Turnover in Acidic Forest Soils in SW Sweden

SW Sweden has very acidic forest soils because of deposition ofair-borne pollutants. Large-scale liming and fertilization have been proposed as countermeasures against a possible future development of forest decline. To test the effects of suggested treatments, liming (3 or 6 t ha¹) and fertilization with easily soluble PK (25 or 50 kg P, 80 or 160 kg K ha¹) or N(20 kg N ha¹ annually in the form of NH₄ NO₃) were applied in different combinations in four experiments in 30–60 yr-old Picea abies forests in SW Sweden. Four yearsafter the initial application of the fertilizers, samples were taken from the O-horizon and the two uppermost 5 cm thick layersof the mineral soil. Their pH(H₂O) and easily extractable Ca, Mg, K, P and inorganic N contents were analyzed. Samples werealso incubated to estimate net N mineralization and potential nitrification rates. Liming increased the pH by 0.6–1 unit in the O-horizon, and by 0.1 unit in the mineral soil. The Ca + Mg content increased by 15–25 kmol_c ha¹ (4–8 foldincrease) in the O-horizon of the limed plots, while an increaseof 5 kmol_c ha¹ (two-fold increase) was observed in theuppermost 5 cm of the mineral soil. Liming did not affect extractable P, K or inorganic N contents. Net N mineralization and potential nitrification rates in the O-horizon were enhanced 1.5- and 6-fold, respectively, by liming, but it had no apparenteffect in the mineral soil. N fertilization caused a slight increase (1.5 kg ha¹) in the content of inorganic N, buthad no effects on the other variables measured. The amount ofextractable P was raised by 16 kg ha¹ in plots given the high P dose (50 kg ha¹), but no other effects of PK fertilization were detected.     

Evaluation of Coal Fly Ash-Based Synthetic Aggregates as a Soil Ameliorant for the Low Productive Acidic Red Soil

A potential new way of producing coal fly ash-based granular synthetic aggregates (CSA) using waste coal fly ash (CFA), paper waste, lime, and gypsum and their utilization as a soil ameliorant to improve crop production in low productive acidic red soil in Okinawa, Japan were studied. The red soil was amended with CSA at three different mixing ratios (i.e., CSA/soil—1:1, 1:5, and 1:10) for the cultivation of Brassica rapa var. Pervidis commonly known as Komatsuna, and the physico-chemical parameters of CSA–soil mixtures and plant growth were analyzed. Incorporation of CSA to the red soil improved the physical and chemical properties of the soil such as water holding capacity, hydraulic conductivity, bulk density, pH, exchangeable cation concentration, cation exchange capacity, particle size distribution, soil pH, electrical conductivity, and carbon content. CSA amendment at ratios of 1:1, 1:5, and 1:10 decreased bulk density by 29.39%, 14.28% and 11.11%, respectively, compared to the original red soil. The acidic pH of the red soil (5.12) was increased to 7.13 and 6.37 by CSA/soil ratios of 1:5 and 1:10, respectively. CSA amendment in soil at 1:5 ratio increased water holding capacity, saturated hydraulic conductivity, electrical conductivity, cation exchange capacity, carbon, potassium (K), magnesium (Mg), and calcium (Ca) content by 0.06 kg kg^?1, ten times, 15.95 mS m^?1, 1.76 cmol_c kg^?1, 6.07 g kg^?1, 0.42 g kg^?1, 0.24 g kg^?1, and 3.38 g kg^?1, respectively, in comparison to the original red soil. Heavy metal contents of the CSA–soil mixtures were below the maximum pollutant concentrations suggested by the US Environmental Protection Agency. Moreover, Na, K, Mg, Ca, copper (Cu), and zinc (Zn) contents in the CSA–soil mixtures increased in comparison with the original red soil. CSA amendment in soil at the ratio of 1:5 and 1:10 resulted in an increase in plant height and plant fresh weight by three and 12 times, respectively, and there was increase in N, K, Mg, Ca, Cu, and Zn contents of the shoots. The results suggest that utilization of eccentric CSA as soil amendment agent can be regarded as an effective waste management practice.     

Copper Accumulations in Soils,Coffee, Banana,and Bean Plants Following Copper-Based Fungicides in Coffee Farms in Arusha and Kilimanjaro Regions,Tanzania

This study was carried out to investigate the levels of copper (Cu) contamination in coffee fields in Kilimanjaro and Arusha regions, Tanzania, to increase the database on the contamination of soils by Cu-based fungicides in coffee fields. Surface (0–20 cm deep) soil samples were collected from different farms in Kilimanjaro and Arusha regions. Coffee, banana, and bean plant samples were collected from the locations of soil sampling. Soil and plant samples were analyzed at the Department of Soil Science, Sokoine University of Agriculture, Morogoro, Tanzania. It was found that the calcium chloride (CaCl₂)–extractable Cu was less than the detection limit of flame atomic absorption spectrometry. Diethylenetriaminepentaacetic acid (DTPA)–extractable (24 to 366 mg Cu kg^?1 soil) and aqua regia–extractable (80 to 806 mg Cu kg^?1 soil) Cu levels were high enough to raise environmental alarm (based on European Union guidelines) in the Cu fungicide–treated soils as compared with natural Cu levels in untreated soils (1 to 12 mg Cu kg^?1 soil for DTPA and 22 to 32 mg Cu kg^?1 soil for aqua regia–extractable Cu). Coffee, banana, and bean plants grown on soils contaminated by Cu fungicides had varied concentrations of Cu that were greater than the concentrations of Cu in the plants collected from the uncontaminated soils. Stepwise regression analysis carried out to investigate the relationships between the soil properties and the concentrations of Cu in plants revealed a significant (P = 0.01) positive relationship (R² = 0.4) between organic carbon and the concentration of Cu in banana leaves. Aqua regia–extractable Cu was positively correlated (P = 0.03, R² = 0.4) with the concentrations of Cu in banana leaves. For bean leaves, electrical conductivity (EC) had a positive significant (P = 0.01) relationship (R² = 0.56) with the concentrations of Cu in the plants. It is recommended that further research be carried out to investigate the dynamics and bioavailability of Cu for the different crops interplanted in the coffee fields.     

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.     

Lime and Cattle Manure in Soil Fertility and Soybean Grain Yield Cultivated in Tropical Soil

Most tropical soils have high acidity and low natural fertility. The appropriate application of lime and cattle manure corrects acidity, improves physical and biological properties, increases soil fertility, and reduces the use of chemical and/or synthetic fertilizers by crops, such as soybean, the main agricultural export product of Brazil. This study aimed to assess the effects of the combination of the application of dolomite limestone (0, 5, and 10 Mg ha^?1) and cattle manure (0, 40, and 80 Mg ha^?1) on grain yield and the chemical properties of an Oxisol (Red Latosol) cultivated with soybean for two consecutive years. The maximum grain yield was obtained with the application of 10 Mg ha^?1 of lime and 80 Mg ha^?1 of cattle manure. Liming significantly increased pH index, the concentrations of calcium (Ca²⁺) and exchangeable magnesium (Mg²⁺), and cation exchange capacity (CEC) of soil and reduced potential acidity (H⁺ + Al³⁺), while the application of cattle manure increased pH level; the concentrations of potassium (K⁺), Ca²⁺, and exchangeable Mg²⁺; and CEC of the soil. During the 2 years of assessment, the greatest grain yields were obtained with saturation of K⁺, Ca²⁺, and Mg²⁺ in CEC at the 4.4, 40.4, and 17.5 levels, respectively. The results indicated that the ratios of soil exchangeable Ca/Mg, Ca/K, K/Mg, and K/(Ca+Mg) can be modified to increase the yield of soybean grains.     

Soil-Applied Nitrogen and Composted Manure Effects on Soybean Hay Quality and Grain Yield

ABSTRACT

Grain yield in many soybean experiments fails to respond to fertilizer nitrogen (N). A few positive responses have been reported when soybean were grown in the southern U.S., when N was applied near flowering and when biosolids were added. In a previous study, low N concentrations of soybean forage in north Texas on a high pH calcareous soil were reported and thus, we suspected a N nutrition problem. Consequently, we initiated this study to determine whether selected preplant N sources broadcast and incorporated into a Houston Black clay (fine, smectitic, thermic Udic Haplusterts) might increase forage N concentration, forage yield, or soybean grain yield. In 2003, N was applied as ammonium nitrate (NH₄NO₃, AN) up to 112 kg N ha^{? 1} and dairy manure compost (DMC) was applied at rates of 4.9, 9.9, 15.0, and 19.9 Mg ha^{? 1}. The DMC contained 5.9, 2.6, and 6.7 g kg^{? 1} of total N, P, and K, respectively; thus DMC added 29 to 116 kg N ha^{? 1}. In 2004, AN was applied at rates of 112 and 224 kg N ha^{? 1} and DMC was applied at 28 and 57 Mg ha^{? 1}; thus, DMC added 168 to 335 kg N ha^{? 1}. In another 2004 test, biosolids, a biosolids/municipal yard waste compost mixture (BYWC), and AN were compared. The biosolids contained 31, 18, and 2.9 g kg^{? 1} total N, P, and K, respectively. The BYWC mixture contained 8.8, 6.1, and 3.4 g kg^{? 1} of total N, P, and K, respectively. Biosolids were applied at 10 Mg ha^{? 1} (310 kg N ha^{? 1}), BYWC was applied at 58 Mg ha^{? 1} (510 kg N ha^{? 1}), and AN up to 224 kg N ha^{? 1}. None of the soil treatments increased soybean grain yield or forage yield although AN slightly increased forage N concentration in 2003.