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.     

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%.     

Does the potential ammonium fixation of soils have an impact on the optimum nitrogen fertilizer rate?

Field experiments were conducted to determine the effect of nitrogen (N) fertilizer forms and doses on wheat (Triticum aestivum L.) on three soils differing in their ammonium (NH₄) fixation capacity [high = 161 mg fixed NH₄-N kg^?1 soil, medium = 31.5 mg fixed NH₄-N kg^?1 soil and no = nearly no fixed NH₄-N kg^?1 soil]. On high NH₄⁺ fixing soil, 80 kg N ha^?1 Urea+ ammonium nitrate [NH₄NO₃] or 240 kg N ha^?1 ammonium sulfate [(NH₄)₂SO₄]+(NH₄)₂SO₄, was required to obtain the maximum yield. Urea + NH₄NO₃ generally showed the highest significance in respect to the agronomic efficiency of N fertilizers. In the non NH₄⁺ fixing soil, 80 kg N ha^?1 urea+NH₄NO₃ was enough to obtain high grain yield. The agronomic efficiency of N fertilizers was generally higher in the non NH₄⁺ fixing soil than in the others. Grain protein was highly affected by NH₄⁺ fixation capacities and N doses. Harvest index was affected by the NH₄⁺ fixation capacity at the 1% significance level.     

Analysis of Citrus Orchard Efficiency in Relation to Soil Properties

ABSTRACT

Orchard efficiency (OE) is one of the indices of evaluating the sustainability in production behavior of citrus orchards. A wide range of soil properties broadly categorized into particle size distribution, water soluble and exchangeable cations, and soil available nutrients were investigated in relation to efficiency of Nagpur mandarin (Citrus reticulata Blanco) orchards established on smectite rich three soil orders (Entisols, Inceptisols, and Vertisols) representing 18 locations of central India. The soil properties, viz., free calcium carbonate (CaCO₃), clay content, water soluble- and exchangeable-calcium (Ca^{2 +}), available nitrogen (N), phosphorus (P), and zinc (Zn) contributed significantly towards variation in OE. The threshold limit of these limiting soil properties was further established using multivariate quadratic regression models as: 132.1 g kg^{? 1} free CaCO₃, 418.1 g kg^{? 1} clay, 149.9 mg L^{? 1} water soluble Ca^{2 +}, 25.9 cmol(p⁺) kg^{? 1} exchangeable Ca^{2 +}, 114.6 mg kg^{? 1} available N, 12.8 mg kg^{? 1} available P, and 0.96 mg kg^{? 1} available Zn in relation to optimum OE of 82.1%. These reference values were very close to those obtained from best fit models, and could be effectively utilized in addressing soil related production constraints for precision-aided citriculture.     

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.     

Assessment of Phosphorus Requirements of Wheat on Different Textured Alluvial Soils through Freundlich Type Equations

Once soil solution phosphorus (P) level optimum for plant growth is identified, P adsorption isotherms or their equations can further be used to estimate fertilizer P rates required to adjust this desired soil solution P level to obtain maximum yield. Surface soil samples were collected from a farmer's field area and research area. An adsorption study was conducted on Ustic Endoaquerts (S₁ soil), Typic Calciargids (S₂ soil), and Typic Torripsamments (S₃ soil) to develop the Freundlich-type equations. Phosphorus adsorption data were obtained by equilibrating 10-g soil samples in 100 mL of 0.01 M calcium chloride (CaCl₂) containing various amounts of monopotassium phosphate (KH₂PO₄). Values of 1/n (slope) ranged from 0.4827 to 0.6452 L kg^?1. Based on 1/n values, it was inferred that each of the two S₁ and S₃ soils was homogeneous and S₂ was not. The K_F (mg P kg^?1) values of S₁, S₂, and S₃ soils were 92.45, 55.81, and 23.38, respectively. The highest amount of P (92.45 mg kg^?1) was adsorbed at unit EPC in S₁ soil, whereas the lowest amount (23.38 mg P kg^?1) was adsorbed in S₃ soil. Thereafter, 11 P fertilizer doses were calculated by these Freundlich-type equations to adjust different estimated soil solution P levels that were designated as treatments (0.05 to 0.90 mg L^?1). Then field experiments on wheat (cv. Inqalab-91) were conducted according to a randomized complete block design (RCBD) on these soils to determine internal (plant tissue), external (soil solution), and fertilizer P requirements. Maximum wheat gain yield (Mg ha^?1) was 6.82 with T₅ (0.25 mg P L^?1) on S₁ soil, 5.96 with T₅ (0.25 mg P L^?1) on S₂ soil, and 4.97 with T₇ (0.40 mg P L^?1) on S₃ soil that was obtained by application of 196 kg P₂O₅ ha^?1 on S₁ soil, 142 kg P₂O₅ ha^?1 on S₂ soil, and 78 kg P₂O₅ ha^?1 on S₃ soil. Internal P concentration (%) associated with 95% of maximum wheat yield at booting stage was 0.32 in S₁, 0.21 in S₂, and 0.33 in S₃ soil. In straw, it was 0.123% in S₁, 0.080% in S₂, and 0.108% in S₃ soil. The internal P requirement of wheat grain was 0.39% in S₁, 0.40% in S₂, and 0.37% in S₃ soil. External soil solution P requirement (ESPR) for 95% of maximum yield of wheat was 0.45 mg L^?1 in S₁ soil, 0.34 mg L^?1 in S₂ soil, and 0.44 mg L^?1 in S₃ soil. Quantity of P₂O₅ corresponding to ESPR values were 217 kg ha^?1 on S₁, 123 kg ha^?1 on S₂, and 60 kg ha^?1 on S₃ soil. Putting ESPR values in the respective Freundlich-type equation, P fertilizer rates (kg P₂O₅ ha^?1) were estimated that were 282 on S₁, 167 on S₂, and 83 on S₃ soil; Practically, 262, 156, and 78 kg P₂O₅ ha^?1 was applied in the field to adjust soil solution P level (mg L^?1) at 0.40 (T₇), 0.30 (T₆), and 0.40 (T₇) in S₁, S₂, and S₃ soil, respectively, that are somewhat less than determined ESPR values. Phosphorous doses applied to achieve a desired EPAS value or estimated from graphs against predicted ESPR values, or calculated from corresponding Freundlich-type equations using desired ESPR values are in close proximity to one another. Therefore, any of the techniques can be used interchangeably to estimate the P fertilizer requirement for optimum wheat yield.     

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.     

Pilot-scale counter-current acid leaching process for Cu,Pb, Sb,and Zn from small-arms shooting range soil

Purpose

The main objective of this study was to evaluate the potential of a counter-current leaching process (CCLP) on 14 cycles with leachate treatment at the pilot scale for Pb, Cu, Sb, and Zn removal from the soil of a Canadian small-arms shooting range.

Materials and methods

The metal concentrations in the contaminated soil were 904?±?112 mg Cu kg^–1, 8,550?±?940 mg Pb kg^–1, 370?±?26 mg Sb kg^–1, and 169?±?14 mg Zn kg^–1. The CCLP includes three acid leaching steps (0.125 M H₂SO₄?+?4 M NaCl, pulp density (PD)?=?10 %, t?=?1 h, T?=?20 °C, total volume?=?20 L). The leachate treatment was performed using metal precipitation with a 5-M NaOH solution. The treated effluent was reused for the next metal leaching steps.

Results and discussion

The average metal removal yields were 80.9?±?2.3 % of Cu, 94.5?±?0.7 % of Pb, 51.1?±?4.8 % of Sb, and 43.9?±?3.9 % of Zn. Compared to a conventional leaching process, the CCLP allows a significant economy of water (24,500 L water per ton of soil), sulfuric acid (133 L H₂SO₄ t^–1), NaCl (6,310 kg NaCl t^–1), and NaOH (225 kg NaOH t^–1). This corresponds to 82 %, 65 %, 90 %, and 75 % of reduction, respectively. The Toxicity Characteristic Leaching Procedure test, which was applied on the remediated soil, demonstrated a large decrease of the lead availability (0.8 mg Pb L^–1) in comparison to the untreated soil (142 mg Pb L^–1). The estimated total cost of this soil remediation process is 267 US$ t^–1.

Conclusions

The CCLP process allows high removal yields for Pb and Cu and a significant reduction in water and chemical consumption. Further work should examine the extraction of Sb from small-arms shooting range.     

GREENHOUSE GAS EMISSIONS FROM AN ALKALINE SALINE SOIL CULTIVATED WITH MAIZE (ZEA MAYS L.) AND AMENDED WITH ANAEROBICALLY DIGESTED COW MANURE: A GREENHOUSE EXPERIMENT

Sludge derived from cow manure anaerobically digested to produce biogas (methane; CH₄) was applied to maize (Zea mays L.) cultivated in a nutrient-low, alkaline, saline soil with electrolytic conductivity 9.4 dS m^?1 and pH 9.3. Carbon dioxide (CO₂) emission increased 3.1 times when sludge was applied to soil, 1.6 times when cultivated with maize and 3.5 times in sludge-amended maize cultivated soil compared to the unamended uncultivated soil (1.51 mg C kg^?1 soil day^?1). Nitrous oxide (N₂O) emission from unamended soil was -0.0004 μg nitrogen (N) kg^?1 soil day^?1 and similar from soil cultivated with maize (0.27 μg N kg^?1 soil day^?1). Application of sludge increased the N₂O emission to 4.59 μg N kg^?1 soil day^?1, but cultivating this soil reduced it to 2.42 μg N kg^?1 soil day^?1. It was found that application of anaerobic digested cow manure stimulated maize development in an alkaline saline soil and increased emissions of CO₂ and N₂O.     

施磷对麦/玉/豆套作体系土壤磷素变化的影响

小麦/玉米/大豆带状套作是四川省丘陵低山区主要旱地作物生产体系,了解该体系磷养分变化对优化磷肥管理和促进可持续生产有重要意义。本研究通过连续3年(2011—2013年)田间定位试验,设置P0、P1、P2、P3和P4共5个磷(P2O5)水平(玉米带分别为0 kg·hm-2、37.5 kg·hm-2、75 kg·hm-2、112.5 kg·hm-2、150 kg·hm-2,小麦-大豆带分别为0 kg·hm-2、45 kg·hm-2、90 kg·hm-2、135 kg·hm-2、180 kg·hm-2),探讨该体系中土壤全磷、速效磷、水溶性磷的变化规律和速效磷的年际变化。结果表明:在麦/玉/豆套作体系中施磷165 kg(P2O5)·hm-2(玉米带75 kg·hm-2,小麦-大豆带90 kg·hm-2),可以满足体系作物对磷的需求,基本达到磷的表观平衡,维持土壤速效磷含量在20 mg·kg-1左右。3年后5个磷水平下体系耕层土壤(0~20 cm)全磷变化量分别为-0.024 g·kg-1·a-1、-0.016 g·kg-1·a-1、0.016 g·kg-1·a-1、0.11 g·kg-1·a-1、0.15 g·kg-1·a-1,速效磷变化量依次为-1.2 mg·kg-1·a-1、-0.9 mg·kg-1·a-1、0.2 mg·kg-1·a-1、2.0 mg·kg-1·a-1和2.7 mg·kg-1·a-1。通过线性平台函数的模拟,该体系中玉米、小麦、大豆产量的土壤速效磷临界值分别为16.5 mg·kg-1、12.6 mg·kg-1和8.8 mg·kg-1。当土壤全磷含量低于0.55 g·kg-1时,土壤全磷每增加0.1 g·kg-1,土壤速效磷增加1.70 mg·kg-1;当土壤全磷大于0.55 g·kg-1,全磷每增加0.1 g·kg-1,土壤速效磷增加6.49 mg·kg-1。当土壤速效磷含量在40 mg·kg-1以下时,速效磷每增加1 mg·kg-1,水溶性磷增加0.017 mg·kg-1。综上,在麦/玉/豆体系磷肥管理中应该维持土壤全磷含量低于0.55 g·kg-1,同时速效磷含量在20 mg·kg-1左右,这样既可以保证作物产量和系统生产力又不会产生较大的环境威胁。     

Bio-extraction of Potassium from Glauconite Nano-particle in an Alfisols of Southern India

ABSTRACT

Glauconite is a potassium (K) bearing mineral, which generally contains 6–10% K₂O and mostly available in various natural deposits in India. Glauconite mineral was converted to nano-particle form by grinding in a high-energy ball mill. The release of K from glauconite nano-particle in soil was studied in a pot culture experiment. Five different treatments viz., 0 mg K₂O kg^?1, 100 mg K₂O kg^?1, 150 mg K₂O kg^?1, 200 mg K₂O kg^?1 used glauconite nano-particle (GNP) as a K source and 100 mg K₂O kg^?1 from muriate of potash (MOP), were applied in soil to grow maize (Zea mays L.) plant. The highest K⁺ concentration was observed in shoot at the application of 200 mg K₂O kg^?1 through GNP and recorded 2 times more K⁺ concentration in shoots as compared to 0 mg K₂O kg^?1 treatment whereas 1.1 times more than the MOP treated soil at 5^th harvesting stage. Selected plant physiological parameters namely electrical conductivity of plant cell, height, leaf area and nitrate reductase activity were also recorded maximum at 200 mg K₂O kg^?1 GNP treated soil. Overall, glauconite nano-particle could supply K throughout the growth period and enhanced biomass yield of maize plant without showing any K deficiency symptom.     

Phosphorus Management of Lucerne Grown on Calcareous Soil in Turkey

ABSTRACT

Lucerne or alfalfa (Medicago sativa L.) is grown as a forage crop on many livestock farms. In calcareous soils in eastern Turkey, lucerne production requires phosphorus (P) additions as the soils are naturally P deficient. Phosphorus sorption isotherms were used to estimate P fertilizer needs for lucerne grown for two years in a 3-cut system on a calcareous P deficient Aridisol in eastern Anatolia, Erzurum province, Turkey. Annual P applications ranged from 0–1200 kg P ha^?1. The Langmuir two-surface adsorption equation was used to derive the maximum P sorption capacity of unamended soil and to determine soil solution P, maximum buffer capacity (MBC), equilibrium buffer capacity (EBC), and P saturation at the optimum economic P rate (OEPR) for dry matter (DM) production. Soils were tested for Olson P at the onset of the study and after two years of P applications. In both years, tissue was analyzed for P content at flowering prior to first cutting. The OEPR (2-year average) was 754 kg P ha^?1 yr^?1 corresponding with a soil solution P concentration of 0.30 mg L^?1, a DM yield of 8725 kg DM ha^?1, and $528 ha^?1 annual profit. The P content of leaves at flowering increased linearly with P application beyond 100 kg P ha^?1 and was 3.2 g kg^?1 P at the OEPR. The unfertilized soil had an EBC, MBC, P saturation, and X_max of 3304 mL g^?1, 3401 mL g^?1, 6%, and 1086 mL g^?1, respectively, whereas two years of fertilization to the OEPR decreased EBC and MBC to 358 mL g^?1 and 540 mL g^?1, and increased P saturation and Olsen P to 56% and 32 mg kg^?1, respectively. These results suggest a P saturation >50% or Olsen P >30 mg kg^?1 are needed to maintain an optimum soil solution concentration of 0.30 mg L^?1 in this calcareous Aridisol. Similar studies with different soils and initial soil test P levels are needed to conclude if these critical soil test values can be applied across the region.     

Application of Organic Wastes in a Soil Polluted with Different Rates of Cr-Pb: Effects on Soil Biological Properties

An experiment was performed to determine the effects of adding municipal solid waste (MSW) and poultry manure (PM) to a soil polluted with chromium (Cr), lead (Pb), and Cr + Pb on the biological parameters of the soil. Soil was mixed with two solutions of Cr(NO₃)₃ and/or Pb(NO₃)₂ to give three concentrations (0, 100, and 250 mg Cr kg^?1 soil and 0, 100, and 250 mg Pb kg^?1 soil) and treated with MSW or PM. When the soil was contaminated with the metals without combining, the greatest adenosine triphosphate (ATP), urease, and phosphatase inhibition percentages occurred for 250 mg Pb kg^?1 soil. When the heavy metals were mixed, the inhibition of the biochemical parameters increased. The application of MSW and PM decreased the inhibition of the biochemical parameters and microbial population in the polluted soils. The inhibition percentage was greater for the soil amended with MSW than with PM, possibly due to the high humic acid concentration.     

Influence of Foliar and Ground Fertilization on Yield,Fruit Quality,and Soil,Leaf, and Fruit Mineral Nutrients in Apple

ABSTRACT

The effectiveness of nitrogen (N)+ zinc (Zn) soil and foliar fertilizer applications on growth, yield, and quality of apple (Malus domestic Borkh ‘Golden Delicious’) fruit was studied in the Zanjan province, Iran. There were eight treatments 1) control (no fertilizer), 2) soil applied N, 3) soil applied Zn, 4) soil applied N+Zn, 5) foliar applied N, 6) foliar applied Zn, 7) foliar applied N+Zn and 8) combined soil and foliar applied N+Zn. The N source was urea [CO(NH₂)₂, 46% N] applied at 276 N tree^{? 1} yr^?1 and the Zn source was zinc sulfate (ZnSO₄,7H₂0, 23% Zn) applied at 110 g Zn tree^{? 1} yr^{? 1}. The soil treatments of N and Zn, were applied every two weeks during June through August (total of 6 times/year) in a 1 m radius around the tree trunk (drip line of trees). The foliar solutions of N (10 g l^{? 1} urea) and Zn [8 g l^{? 1} zinc sulfate (ZnSO₄)] were sprayed at the rate of 10 L tree^{? 1} every two weeks at the same times as described for soil applications. The highest yield (49 kg tree^{? 1}), and the heaviest fruits (202 g) were obtained in the soil and foliar combination of N+Zn treatment. The lowest yield (35 kg tree^{? 1}), and the smallest fruits (175 g) were recorded in the control. Nitrogen, and to a lesser extent Zn, foliar application resulted in decreasing fruit quality (caused russeting, and lower soluble solid), but increasing N leaf and fruit concentrations (2.4% DW and 563 mg kg^{? 1}, respectively). There were significant differences among yield and leaf mineral nutrient concentration in different treatments. But there was no significant difference between fruit mineral nutrient concentration (except N). Ratio of N/calcium (Ca), potassium (K)/Ca, and [magnesium (Mg)+K]/Ca in fruits were found suitable for fruit quality prediction. Combining the zinc sulfate with urea in the foliar applications increased the concentration of Zn from 0.7 to 1.5 mg per kg of apple tissue. Leaf N concentration varied during growth season. Foliar applied nutrient can be more efficient than soil applied, but a combination of soil and foliar applications is recommended for apple tree nutrient management.     

Interaction of soil boron application with leaf B concentration,root length density,and canopy size of citrus affected by Huanglongbing

Abstract

Good and balanced citrus nutrition is important for high fruit yields and improved tree performance. A study was conducted for 2?years to investigate the effect of soil application of boron (B) on leaf nutrient content, canopy size, and root length density (RLD). The study was conducted on 10-year-old Candidatus Liberibacter asiaticus (CLas)-infected Vernia sweet orange on Rough Lemon rootstock in a commercial grove east of St. Cloud, FL planted at 375 trees ha^?1 on a traditional soluble dry nutrition and spray programs. Treatments were supplied with various ground-applied controlled-release fertilizer treatments containing B. Boron was applied at 0×, 2×, and 4× current University of Florida recommendation where 1×?=?1.12?kg ha^?1. Data collected included leaf B nutrient content, soil B concentration, trunk diameters, canopy volumes, soil electrical conductivity, and soil pH. The 0×, 2×, and 4× application rates corresponded with leaf nutrient contents ranging from 56?mg kg^?1 and 88?mg kg^?1 in March 2017, 162?mg kg^?1 and 288?mg kg^?1 in September 2017, and 122?mg kg^?1 and 320?mg kg^?1 in May 2018. Temporary, RLD decreased with time from March to September 2017 by 13, 30, and 37% at the 0, 2.24, and 4.48?kg B ha^?1 and increased by 309, 258, and 306% at the 0, 2.24, and 4.48?kg B ha^?1, respectively, from September 2017 to May 2018. No consistent pattern was established between soil B application with canopy size.     

Acid deposition and ion leaching from a podzolic soil under hardwood forest

The contribution of atmospheric acids to cation leaching from a podzolic soil under mature maple-birch forest in central Ontario was examined during 1983. The movement of base cations was associated largely with NO₃ ^?, SO₄ ^2? and organic acid anions in surface soil horizons, with SO₄ ^2? and NO₃ ^? below the effective rooting zone, and SO₄ ^2? and HCO₃ ^? in streamflow. Mineral soil horizons could adsorb little additional SO₄ ^2? or associated cations at current soil solution SO₄ ^2? concentrations. Therefore it is concluded that the soil in situ lacks a strong affinity for SO₄ ^2?. Current annual inputs to the forest of SO₄ ^2? and NO₃ ^? in bulk precipitation (26.4 and 18.2 kg ha^?1, equivalent to 8.8 kg S and 4.1 kg N ha^?1 , respectively) contributed significantly to cation leaching from the soil. In order to maintain exchangeable cations in soil at current levels, a rate of weathering yielding 29.6, 5.0, 4.4 and 2.2 kg ha^?1 yr^?1 of Ca²⁺, Na⁺, Mg²⁺ and K⁺, respectively, would be required.     

Modeling of Interactive Effects of Rainfall,Evaporation, Soil Temperature,and Soil Fertility for Sustainable Productivity of Sorghum + Cowpea and Cotton + Black Gram Intercrops under Rotation Trials in a Rain-Fed Semi-arid Vertisol

Long-term effects of the different combinations of nutrient-management treatments were studied on crop yields of sorghum + cowpea in rotation with cotton + black gram. The effects of rainfall, soil temperature, and evaporation on the status of soil fertility and productivity of crops were also modeled and evaluated using a multivariate regression technique. The study was conducted on a permanent experimental site of rain-fed semi-arid Vertisol at the All-India Coordinated Research Project on Dryland Agriculture, Kovilpatti Centre, India, during 1995 to 2007 using 13 combinations of nutrient-management treatments. Application of 20 kg nitrogen (N) (urea) + 20 kg N [farmyard manure (FYM)] + 20 kg phosphorus (P) ha^?1 gave the greatest mean grain yield (2146 kg ha^?1) of sorghum and the fourth greatest mean yield (76 kg ha^?1) of cowpea under sorghum + cowpea system. The same treatment maintained the greatest mean yield of cotton (546 kg ha^?1) and black gram (236 kg ha^?1) under a cotton + cowpea system. When soil fertility was monitored, this treatment maintained the greatest mean soil organic carbon (4.4 g kg^?1), available soil P (10.9 kg ha^?1), and available soil potassium (K) (411 kg ha^?1), and the second greatest level of mean available soil N (135 kg ha^?1) after the 13-year study. The treatments differed significantly from each other in influencing soil organic carbon (C); available soil N, P, and K; and yield of crops attained under sorghum + cowpea and cotton + black gram rotations. Soil temperature at different soil depths at 07:20 h and rainfall had a significant influence on the status of soil organic C. Based on the prediction models developed between long-term yield and soil fertility variables, 20 kg N (urea) + 20 kg N (FYM) + 20 kg P ha^?1 could be prescribed for sorghum + cowpea, and 20 kg N (urea) + 20 kg N (FYM) could be prescribed for cotton + black gram. These combinations of treatments would provide a sustainable yield in the range of 1681 to 2146 kg ha^?1 of sorghum, 74 to 76 kg ha^?1 of cowpea, 486 to 546 kg ha^?1 of cotton, and 180 to 236 kg ha^?1 of black gram over the years. Beside assuring greater yields, these soil and nutrient management options would also help in maintaining maximum soil organic C of 3.8 to 4.4 g kg^?1 soil, available N of 126 to 135 kg ha^?1, available soil P of 8.9 to 10.9 kg ha^?1, and available soil K of 392 to 411 kg ha^?1 over the years. These prediction models for crop yields and fertility status can help us to understand the quantitative relationships between crop yields and nutrients status in soil. Because black gram is unsustainable, as an alternative, sorghum + cowpea could be rotated with cotton for attaining maximum productivity, assuring sustainability, and maintaining soil fertility on rain-fed semi-arid Vertisol soils.     

Effects of Organic and Inorganic Fertilizers on Soil and Plant Nutrients and Yields of Pearl Millet and Wheat under Semi-arid Inceptisols in India

A study was conducted to assess fertilizer effect on pearl millet–wheat yield and plant-soil nutrients with the following treatments: T₁, control; T₂, 100% nitrogen (N); T₃, 100% nitrogen and phosphorus (NP); T₄, 100% nitrogen, phosphorus and potassium (NPK); T₅, 100% NPK + zinc sulfate (ZnSO₄) at 25 kg ha^?1; T₆, 100% NPK + farmyard manure (FYM) at 10 t ha^?1; T₇, 100% NPK+ verimcompost (VC) at 2.5 tha^?1; T₈, 100% NPK + sulfur (S) at 25 kg ha^?1; T₉, FYM at 10 t ha^?1; T₁₀, VC at 2.5 t ha^?1; T₁₁, 100% NPK + FYM at 10 t ha^?1 + 25 kg S ha^?1 + ZnSO₄ at 25 kg ha^?1; and T₁₂, 150% NPK treatments. Treatments differed significantly in influencing soil-plant nutrients and grain and straw yields of both crops. Grain yield had significant correlation with soil-plant N, P, K, S, and zinc (Zn) nutrients. The study indicated superiority of T₁₁ for attaining maximum pearl millet grain yield (2885 kg ha^?1) and straw yield (7185 kg ha^?1); amounts of N (48.9 kg ha^?1), P (8.8 kg ha^?1), K (26.3 kg ha^?1), S (20.6 kg ha^?1), and Zn (0.09 kg ha^?1) taken up; and amounts of soil N (187.7 kg ha^?1), P (13.7 kg ha^?1), K (242.5 kg ha^?1), S (10.1 kg ha^?1), and Zn (0.70 kg ha^?1). It was superior for wheat with grain yield (5215 kg ha^?1) and straw yield (7220 kg ha^?1); amounts of N (120.7 kg ha^?1), P (13.8 kg ha^?1), K (30 kg ha^?1), S (14.6 kg ha^?1), and Zn (0.18 kg ha^?1) taken up; and maintaining soil N (185.7 kg ha^?1), P (14.5 kg ha^?1), K (250.5 kg ha^?1), S (10.6 kg ha^?1), and Zn (0.73 kg ha^?1). Based on the study, 100% NPK + FYM at 10 tha^?1 + Zn at 25 kg ha^?1 + S at 25 kg ha^?1 could be recommended for attaining maximum returns of pearl millet–wheat under semi-arid Inceptisols.     

Application of white mustard and oats in the phytostabilisation of soil contaminated with cadmium with the addition of cellulose and urea

Purpose

Determination of the effectiveness of white mustard and oats in immobilising cadmium as a soil contaminant and determining the role of cellulose and urea in restoring homeostasis in soil under pressure from Cd²⁺.

Materials and methods

Soil samples were contaminated with cadmium (CdCl₂·2¹/₂H₂O) at 0, 4, 8 and 16 mg Cd²⁺ kg^?1. In order to reduce the negative impact of Cd²⁺, cellulose was introduced to the soil at the following rates: 0 and 15 g kg^?1 and urea at 80 and 160 mg N kg^?1. The yield of the above-ground parts and roots was determined on days 40 and 80 of the experiment, along with the cadmium content in the plant material. The enzyme activity was also determined, and the physical and chemical properties of the soil were determined on the day of the oats’ (aftercrop) harvest.

Results and discussion

Contamination of soil with Cd²⁺ at 4 to 16 mg kg^?1 d.m. of soil reduced the yield of white mustard and oats. The tolerance index (TI) values indicate that oats (aftercrop) is more tolerant than white mustard of soil contamination with Cd²⁺. Cadmium accumulated more intensely in roots compared with the above-ground parts of the plants. The translocation index (TF) indicates smaller Cd²⁺ translocation from roots to above-ground parts, as it was below 1 in both plants. An addition of cellulose and nitrogen offsets the adverse impact of cadmium on plants. Arylsulphatase was the most sensitive to soil contamination with Cd²⁺, followed by dehydrogenases, catalase, β-glucosidase and urease, and alkaline phosphatase and acid phosphatase were the least sensitive. Contamination of soil with Cd²⁺ changed its physical and chemical properties only slightly.

Conclusions

White mustard and oats have phytostabilisation potential with respect to soil contaminated with cadmium. Cellulose introduced to the soil and fertilisation with urea alleviated the negative impact of cadmium on the growth and development of plants.

     

Effects of glucose and rhizodeposits (with or without cysteine-S) on immobilized-35S, microbial biomass-35S and arylsulphatase activity in a calcareous and an acid brown soil

Our aim was to study the effects of C (as glucose and artificial rhizodeposits) on S immobilization, in relation to microbial biomass‐S and soil arylsulphatase (ARS) activity, in contrasting soils (a calcareous and an acid brown soil). The glucose‐C and artificial rhizodeposit‐C with or without cysteine were added at six rates (0, 100, 200, 400, 600 and 800 mg kg^?1 soil) to the two soils and then incubated with Na₂³⁵SO₄ for 1 week prior to analysis. The percentages of ³⁵S immobilized increased when C as glucose and rhizodeposit (without cysteine) were added to both soils. With cysteine‐containing rhizodeposit, the percentages of ³⁵S immobilized remained relatively stable (23.5% to 29.9%) in the calcareous soil, but decreased in the acid brown soil (52.7% to 31.5%). For both soils, cysteine‐containing rhizodeposit additions showed no significant correlation between immobilized‐³⁵S and microbial biomass‐³⁵S, suggesting that microorganisms immobilized cysteine‐S preferentially instead of ³⁵S from the tracer (Na₂³⁵SO₄). In the calcareous soil, a positive and significant correlation was found between ARS activity and microbial biomass‐³⁵S (r = 0.85, P < 0.05) when glucose was added. We also saw this correlation in the acid brown soil when rhizodeposit‐C without cysteine was added (r = 0.90, P < 0.05). Accordingly, the results showed the presence of extracellular arylsulphatase activity of 48.7 mg p‐nitrophenol kg^?1 soil hour^?1 in the calcareous soil and of 27.0 mg p‐nitrophenol kg^?1 soil hour^?1 in the acid brown soil.