Influence of Gyttja on Shoot Growth and Shoot Concentrations of Zinc and Boron of Wheat Cultivars Grown on Zinc‐Deficient and Boron‐Toxic Soil

Abstract

Greenhouse experiments were carried out to study the influence of gyttja, a sedimentary peat, on the shoot dry weight and shoot concentrations of zinc (Zn) and boron (B) in one bread wheat (Triticum aestivum L., cv. Bezostaja) and one durum wheat (Triticum durum L., cv. Kiziltan) cultivar. Plants were grown in a Zn‐deficient (DTPA‐Zn: 0.09 mg kg^?1 soil) and B‐toxic soil (CaCl₂/mannitol‐extractable B: 10.5 mg kg^?1 soil) with (+Zn = 5 mg Zn kg^?1 soil) and without (?Zn = 0) Zn supply for 55 days. Gyttja containing 545 g kg^?1 organic matter was applied to the soil at the rates of 0, 1, 2.5, 5, and 10% (w/w). When Zn and gyttja were not added, plants showed leaf symptoms of Zn deficiency and B toxicity, and had a reduced growth. With increased rates of gyttja application, shoot growth of both cultivars was significantly enhanced under Zn deficiency, but not at sufficient supply of Zn. The adverse effects of Zn deficiency and B toxicity on shoot dry matter production became very minimal at the highest rate of gyttja application. Increases in gyttja application significantly enhanced shoot concentrations of Zn in plants grown without addition of inorganic Zn. In Zn‐sufficient plants, the gyttja application up to 5% (w/w) did not affect Zn concentration in shoots, but at the highest rate of gyttja application there was a clear decrease in shoot Zn concentration. Irrespective of Zn supply, the gyttja application strongly decreased shoot concentration of B in plants, particularly in durum wheat. For example, in Zn‐deficient Kiziltan shoot concentration of B was reduced from 385 mg kg^?1 to 214 mg kg^?1 with an increased gyttja application. The results obtained indicate that gyttja is a useful organic material improving Zn nutrition of plants in Zn‐deficient soils and alleviating adverse effects of B toxicity on plant growth. The beneficial effects of gyttja on plant growth in the Zn‐deficient and B‐toxic soil were discussed in terms of increases in plant available concentration of Zn in soil and reduction of B uptake due to formation of tightly bound complexes of B with gyttja.     

Ameliorative Effects of Potassium Phosphate on Salt‐Stressed Pepper and Cucumber

Abstract

Bell pepper (Capsicum annuum cv. Urfa Isoto) and cucumber (Cucumis sativus cv. Beith Alpha F1) were grown in pots containing field soil to investigate the effects of supplementary potassium phosphate applied to the root zone of salt‐stressed plants. Treatments were (1) control: soil alone (C); (2) salt treatment: C plus 3.5 g NaCl kg^?1 soil (C + S); and (3) supplementary potassium phosphate: C + S plus supplementary 136 or 272 mg KH₂PO₄ kg^?1 soil (C + S + KP). Plants grown in saline treatment produced less dry matter, fruit yield, and chlorophyll than those in the control. Supplementary 136 or 272 mg KH₂PO₄ kg^?1 soil resulted in increases in dry matter, fruit yield, and chlorophyll concentrations compared to salt‐stressed (C + S) treatment. Membrane permeability in leaf cells (as assessed by electrolyte leakage from leaves) was impaired by NaCl application. Supplementary KH₂PO₄ reduced electrolyte leakage especially at the higher rate. Sodium (Na) concentration in plant tissues increased in leaves and roots in the NaCl treatment. Concentrations of potassium (K) and Phosphorus (P) in leaves were lowered in salt treatment and almost fully restored by supplementary KH₂PO₄ at 272 mg kg^?1 soil. These results clearly show that supplementary KH₂PO₄ can partly mitigate the adverse effects of high salinity on both fruit yield and whole plant biomass in pepper and cucumber plants.     

Impact of Postharvest Sprays of Nitrogen,Boron and Zinc on Nutrition,Reproductive Response and Fruit Quality of ‘Schattenmorelle’ Tart Cherries

The aim of the study was to examine effects of fall sprays of nitrogen (N), boron (B) and zinc (Zn) on nutrition, reproductive response, and fruit quality of tart cherry (Prunus cerasus L.). The experiment was conducted during 2008–2010 in Poland on mature ‘Schattenmorelle’ sour cherry trees, planted at a spacing of 4.0 × 1.5 m on a coarse-textured soil with low level of organic matter, and adequate reaction and availabilities of macro- and micronutrients. Tart cherries were sprayed with boric acid-B, ethylenediaminetetraacetic acid (EDTA)-Zn, and urea-N at 40–50 d prior to initiation of leaf fall according to following schema: (i) spray of N at a rate of 23 kg ha^?1; (ii) spray of B and Zn at doses of 1.1 kg ha^?1 and 0.5 kg ha^?1, respectively; and (iii) spray of N, B, and Zn at the same rates as in the above spray combinations. The trees sprayed with water were served as the control. The results showed that postharvest spray treatments had no effect on defoliation, cold damage of flower buds, fruit set, yielding, plant N status, mean fruit weight, and soluble solids concentration in fruit. Postharvest sprays of B and Zn with or without N enhanced status of Zn and B in fall leaves, and B in flowers but had no impact on levels of the above micronutrients in summer leaves. Leaf-absorbed B was withdrawn in the fall, whereas Zn was immobile. It is concluded that postharvest B sprays can be recommended to increase B status in flowers of tart cherry, whereas fall sprays of urea-N and Zn are not able to improve plant nutrition of those nutrients the following season.     

Boron and ectomycorrhizal influences on mineral nutrition of container‐grown Pinus ehinata mill

Boron fertilization and inoculation with Pisolithus tinctorius (Pers.) Coker and Couch increased foliar and total seedling nutrient content of boron, calcium, copper, iron, potassium, magnesium, manganese and phosphorus in shortleaf pine seedlings (Pinus echinata Mill.). Noninoculated seedlings fertilized with boron showed no increase in nutrient content other than B. The increase in nutrient content of inoculated seedlings fertilized with boron was correlated with increased mycorrhizal infection. Boron fertilization may affect indirectly the mineral nutrition of tree seedlings by increasing mycorrhizal fungi colonization of their roots.     

Path and Correlation Analyses of the Factors affecting Biomass Production of Brassica Cultivars under Phosphorus‐Deficiency Stress Environment

Abstract

Path analysis is a statistical technique that partitions correlations into direct and indirect effects and distinguishes between correlation and causation, whereas correlation in general measures the extent and direction (positive or negative) of a relationship occurring between two or more variables. The estimates of correlation and path coefficients can help us to understand the role and relative contribution of various plant traits in establishing growth behavior of crop cultivars under given environmental conditions. Dependence of shoot dry‐matter (SDM) production of six hydroponically grown Brassica cultivars on various growth parameters and characteristics of P metabolism was investigated using the modified Johnson's nutrient solution to maintain deficient (10 µM) and adequate (200 µM) P levels. Root dry‐matter (RDM), total dry‐matter, P content in shoot, and P‐utilization efficiency (PUE) had significant and positive effects on production of SDM in a P‐deficient environment. Root–shoot ratio (RSR), however, negatively affected SDM of cultivars exposed to P‐deficient conditions and did not show any impact on SDM production in either of the two treatments. In a pot study, six Brassica cultivars were grown in a sandy loam soil that was deficient in NaHCO₃‐extractable P (3.9 mg P kg^?1 soil) for 49 days. Significant positive correlations were observed between SDM and some other plant traits such as RDM, leaf area per plant, P uptake, and PUE, at both genotypic and phenotypic levels. The correlations of SDM with RSR, however, were not observed, implying that relative partitioning of biomass into roots or shoots had little role to play in SDM production by Brassica cultivars under P‐deficiency stress. Path analysis revealed that favorable impact of RDM and leaf area on SDM production was indirect through positive effect of these parameters on P uptake and PUE. Thus, under P‐deficiency stress, better P acquisition and efficient P utilization by the cultivars for biomass synthesis collectively formed the basis of higher SDM production by the cultivars, evidencing that P uptake and utilization efficiency are two important plant traits for selecting P‐deficiency‐stress‐tolerant Brassica cultivars.     

Impact of rainfall and tillage systems on off‐site herbicide movement

Abstract

Ground cover associated with conservation‐ and no‐till cropping systems can alter runoff and herbicide loss from the soil surface. This study was conducted in 1987 and 1988 to evaluate runoff losses of soil‐applied alachlor and imazaquin in five different soybean cropping systems. Cropping systems used were: 1) conventionally tilled monocrop soybean planted in May; 2) conventionally tilled monocrop soybean planted in June; 3) conventionally tilled doublecrop soybean with incorporated wheat stubble; 4) no‐till doublecrop soybean with burned wheat stubble; and 5) no‐till doublecrop soybean planted into standing wheat stubble. Runoff was lower in 1988 due to a lack of precipitation and dry soil conditions. Herbicide loss in both years was greatest in doublecrop soybean with incorporated wheat stubble, which corresponded to higher runoff. Lower herbicide loss in June‐planted monocrop soybean was attributed to a rougher seedbed that retarded runoff. May‐planted monocrop soybean also lost very little herbicide in 1987, although this treatment had the highest runoff. Lower concentrations of alachlor and imazaquin in runoff from this treatment may be attributed to degradation or soil sorption of herbicides between planting and the first runoff event 23 days later. Highest runoff losses of alachlor and imazaquin, as compared to their initial concentration, were approximately 10% in 1987, and less than 0.5% in 1988. Nomenclature: alachlor, 2‐chloro‐N‐(2, 6‐diethylphenyl) N‐(methoxymethyl) acetamide; imazaquin, 2‐[4, 5‐dihydro‐4‐methyl‐4‐(l‐methyl‐ethyl)‐5‐oxo‐1H‐imadazol‐2‐yl]‐3‐quinolinecarboxylic acid; soybean [Glycine max (L.)] Merr.; wheat (Triticum aestivum L.).     

Long‐Term Application of Biosolids on Apricot Production

Abstract

The use and disposal of biosolids, or wastewater treatment sludge, as a fertilizer and soil amendment is becoming increasingly widespread. We evaluated the multiyear use of biosolids in apricot (Prunus armeniaca L.) production, grown on productive agricultural soils. Class A biosolids were initially applied annually at rates of 0, 1.9, 5.8, and 11.7 Mg · ha^?1 (dry basis) to a 2‐year‐old apricot orchard on the USDA‐ARS research site on the eastern side of the San Joaquin Valley, CA. These application rates provided estimated rates of 0 (control), 57, 170, and 340 kg total N · ha^?1 yr^?1, respectively. Compared to the control treatment, the applications of biosolids significantly increased soil salinity (electrical conductivity from 1:1 soil–water extract) and total concentrations of nutrients [e.g., calcium (Ca), magnesium (Mg), sulfur (S), phosphorus (P), zinc (Zn), and copper (Cu)] after 7 years but did not increase the concentrations of selected metals [cadmium (Cd), chromium (Cr), cobalt (Co), nickel (Ni), and lead (Pb)] between 0‐ and 60‐cm soil depths. Mean concentrations of total nitrogen (N) and carbon (C) in soils (0‐ to 15‐cm depth) ranged from a low of 1.3 g kg^?1 to a high of 5.2 g · kg^?1 and from 14.1 g · kg^?1 to 45.7 g · kg^?1 for the control and high biosolids treated soils, respectively.

Biosolids applications did not lead to fruit yield reductions, although fruit maturation was generally delayed and more fruits appeared at picking times at the high rate of application. Yellow fruits collected from all biosolids applications were significantly firmer than were fruit collected from control trees, and they had higher concentrations of Ca, potassium (K), S, iron (Fe), and Zn in the fruit. Among the fruit quality parameters tested, the juice pH, total acidity, and fruit skin color were not significantly affected by biosolids applications. Malic acid concentrations decreased most of the time, while citric acid concentrations increased with increasing rates of biosolids applications. Overall, our results suggest that nonindustrial biosolids applied at an annual rate at or less than 11.7 Mg N · ha^?1 (340 kg N · ha^?1) can be safely used for apricot production on sandy loam soils.     

Effects of the Polish Rootstocks P2 and P22 on Vigour,Yield and Fruit Characteristics of the Apple Cultivar ‘Gravenstein’

Abstract

The performance of the Polish rootstocks P2 and P22 under Norwegian growing conditions was evaluated over 10 years (1983–92). Tree vigour of the apple cultivar ‘Gravenstein’ on P2 and P22 was 64 and 16% of that on M9, respectively. Trees on P2 had the highest yield efficiency, but less total yield per tree than M9. Owing to very dwarfing growth, trees on P22 failed to establish a sufficient canopy and produced significantly smaller apples. P2 and P22 affected apple soluble solids in a favourable way, but did not influence fruit acidity.     

Effects of Clear‐Cutting Alder Coppice on Surface Soil Properties and Aboveground Herbaceous Plant Biomass

The purpose of this investigation was to evaluate the effects of clear‐cutting and skidding impacts on surface soils in an alder coppice and aboveground herbaceous biomass. For this purpose, experimental sites used in the study were a randomized complete block with four replications. Some soil properties were measured at 60 pits at 0 to 5 cm and 5 to 10 cm deep in control, normal harvest, and main skid trail sites. In the main skid trail site, as compared to the control and normal harvest site, the bulk density increased from 0.90 to 1.52g cm^?3, the soil organic‐matter content decreased from 4.77% to 1.65%, and saturated hydraulic conductivity decreased from 86.34 to 9.6 cm h^?1 at 0 to 5 cm deep. Optimization of harvesting time and rehabilitation of skid roads needed to be done to prevent and minimize negative impacts of the skid roads on soils.     

Nutrition of container‐grown freesias

As limited information is available on the nutrition of freesias an experiment was carried out to examine the influence of nutrients on foliage and corm growth, and flowering of container‐grown plants. The experiment ran for 10 months using seedlings grown in a peat:sand (3:1,v:v) medium with combinations of varying levels of nitrogen (N), phosphorus (P), potassium (K), and lime. Nitrogen fertilization had a significant effect on many aspects of flowering and growth while the response to P was similar except for a lack of influence on spike production. Fertilization of 600–800 g N m^‐3 and at least 200 g P m^‐3 are recommended for strong leaf and corm growth with good flowering. There were few significant responses to added K, except in early foliage growth, while liming increased foliage development. High flowering, leaf, and corm growth should be achieved with a media pH of 5.9 and foliar nutrients of 2.2–2.3% N, 0.25–0.30% P, 4.0–4.5% K, 0.65–0.80% calcium (Ca) and 0.20–0.25% magnesium (Mg).     

Previous Corn Row Effects on Potassium Nutrition and Yield of Subsequent No‐Till Soybeans

Abstract

Narrow‐row soybean [Glycine max (L.) Merr.] production in corn [Zea mays L.]–soybean rotations results in various distances of soybean rows from previous corn rows, yet little is known about soybean responses to proximity to prior corn rows in no‐till systems. The objective of this study was to evaluate the impacts of preceding corn rows on potassium (K) nutrition and yield of subsequent no‐till soybeans. Four field experiments involving a corn–soybean rotation were conducted on long‐term no‐till fields with low to medium K levels from 1998 to 2000 near Paris and Kirkton, Ontario, Canada. In the corn year, treatments included K application rate and placement in conjunction with tillage systems or corn hybrids. Before soybean flowering, soil exchangeable K concentrations (0–20 cm depth) in previous corn rows were significantly higher than those between corn rows. At the initial flowering stage, trifoliate leaf K concentrations of soybeans in preceding corn rows were 2.0 to 5.3 g kg^?1 higher than those from corresponding plants between corn rows. Yield of no‐till soybeans in previous corn rows increased 10 to 44% compared to those between previous corn rows. Positive impacts of prior corn rows on soil K fertility, soybean leaf K, and soybean yield occurred even when K fertilizer was not applied in the prior corn season. Deep banding of K fertilizer tended to accentuate row vs. between‐row effects on soybean leaf K concentrations in low‐testing soils. Corn row effects on soybeans were generally not affected by either tillage system or corn hybrid employed in the prior corn crop. Potassium management strategies for narrow‐row no‐till soybeans should take the potential preceding corn row impacts on soil K distribution into account; adjustments to current soil sampling protocols may be warranted when narrow‐row no‐till soybeans follow corn on soils with low to medium levels of exchangeable K.     

Response of Chickpea Cultivars to Application of Boron in Boron‐Deficient Calcareous Soils

Abstract

This study was conducted to investigate the effects of four boron (B) doses (control, 0 kg B ha^?1; B₁, 1 kg B ha^?1; B₂, 3 kg B ha^?1; and B₃, 6 kg B ha^?1) in soils deficient in available B (0.19 mg B kg^?1) and lime (CaCO₃) content (20.7%) on yield and some yield components of five chickpea (Cicer arietinum L.) genotypes, namely Akçin‐91, Population, Gökçe, ?zmir‐92, and Menemen‐92 in central Anatolian Turkey in the 2002 and 2003 growing seasons. Plant height, pods per plant, grain yield, protein content, protein yield, thousand seed weight, and leaf B concentration were measured. Grain yields in all genotypes (except for Gökçe) were significantly increased by 1 kg ha^?1 B application. Application of 1 kg ha^?1 B increased the yield by an average of 5%. Genotypes studied showed significant variations with respect to their responses to additional B. Akçin‐91 gave the highest grain yield (1704.8 kg ha^?1) at 3 kg B ha^?1, whereas Population, ?zmir‐92, and Menemen‐92 yielded best (1468.2 kg ha^?1, 1483.0 kg ha^?1, and 1484.7 kg ha^?1, respectively) at 1 kg B ha^?1. Interestingly, Gökçe reached to the highest level of grain yield (1827.1 kg ha^?1) at the control. Gökçe was a B deficiency B tolerance genotype. The other genotypes appeared to have high sensitivity to B deficiency. This study showed that B deficiency could result in significant yield losses in chickpea under the experimental conditions tested. Thus, B contents of soils for the cultivation of chickpea should be analyzed in advance to avoid yield losses.     

Boron partitioning in B‐sprayed and unsprayed fruiting twigs of hazelnut

Abstract

Following B sprays, fruit set increase in ‘Barcelona’ hazelnut was accompanied by a decrease in dry‐matter accumulation for the entire fruiting twig. In unsprayed controls prior to 5 June, leaves constituted 80% of the total dry weight of a fruiting twig. Later in the season (5 Aug.) the percent dry weight was maximum in the nut tissue (66%), followed by leaves (17%), and then husks (13%). Leaves contained 87% of the total B in a fruiting twig early in the season, indicating that the leaf was a major sink for B at that time. Of the net B increases over a 2 months period, 24% was in the leaves, 38% in the nuts, and 37% in the husks. By 5 Aug., compared to other tissues, stem dry matter (3%) and B content (32) was negligible; hence, the stem was of little importance in overall partitioning. Boron sprays did not alter B partitioning in the fruiting twigs.     

Pressurized Hot Water and DTPA‐Sorbitol as Viable Alternatives for Soil Boron Extraction. I. Boron‐Treated Soil Incubation and Efficiency of Extraction

Abstract

Serious challenges associated with hot water extraction, the standard extraction method for water‐soluble boron (B), limit its use in commercial soil‐testing laboratories. Several alternatives to make B testing more practical have been proposed and studied; none of the alternatives have readily replaced the hot water method. Two relatively new, promising B extraction methods are pressurized hot water and DTPA‐Sorbitol. Very little reported work compares B extraction values obtained from the standard hot water extraction method and these two alternative methods. This study was conducted to complete an initial step in validating new procedures—extracting the designated nutrient from fertilized, incubated soils by using standard and alternative extraction methods and comparing the resulting values. The three extraction methods were used to extract B from samples of calcareous sand and silt loam soils and limed, loamy fine sand, all which had been treated with 10 levels of B (0–8 mg kg^?1) and incubated for 7 and 28 days. The amount of B extracted increased as the rate of B application increased with all three soil‐extraction methods. High correlations (r 0.977–0.999) were observed between extractable B and rate of B application with all three procedures. Correlations between the amount of extractable B using hot water extraction and the value obtained with an alternative extraction method were similar for both methods (r=0.89). Hot water generally extracted the least and pressurized hot water the most B regardless of soil type, rate of application, or duration of incubation. This study suggests the more easily used methods of pressurized hot water and DTPA‐Sorbitol could be recommended as replacements to the cumbersome hot water extraction.     

Influence of mid‐summer boron sprays on boron content and quality indices of ‘delicious’ Apple 1

Boron (B) is required for optimal yield and quality of apple fruit (Malus domestica Borkh.) but may impair fruit quality if present in excessive amounts. A field experiment was conducted to examine the effects of a single mid‐July foliar B spray (0, 11.3, 22.6 g B/tree) on the B content and postharvest quality indices of 220‐gram ‘Starking Delicious’ apples. Fruit B concentration was positively related to B application rate and ranged from 9 to 55 mg/kg dry mass (1.3 to 7.7 mg/kg fresh mass). The relative B increases were greater in the core and inner cortex than in the outer cortex and skin, suggesting that some of the applied B entered the fruit through the tree vascular system. Increasing fruit B concentrations caused minor changes in fruit external color indices L and b and internal color index b but had no effect on firmness, soluble solids concentration, titratable acidity, starch index, external color index a, or internal color indices L and a. None of the effects were of horticultural significance. Most fruit quality indices were influenced by postharvest sampling time and reflected typical postharvest ripening patterns. The results suggest that ‘Delicious’ apple quality is relatively insensitive to high fruit B concentrations.     

Effect of Calcium and Boron Sprays on Yield and Quality of “Elsanta” Strawberry

Abstract

The aim of the experiment was to examine the effects of foliar applications of calcium (Ca) and boron (B) on yield and fruit quality of “Elsanta” strawberries grown on a sandy loam soil with low status of available B. The study was conducted in 1999–2000 at a commercial strawberry plantation in Central Poland. Cold‐stored strawberries were planted in 1998 at a spacing of 0.25 × 0.8 m. The following treatments were applied: (i) five sprays of Ca as CaCl₂ at a rate of 1.5 kg Ca ha^?1 spray^?1 with addition of Tween 20 adjuvant at 0.1%; the first spray was performed at the petal fall stage and the next at 5‐day intervals; (ii) three sprays of B as Borvit material at a rate of 160 g B ha^?1 spray^?1 at the beginning of flowering and 5, and 10 days later; (iii) sprays of B and Ca as in the combination of (i) and (ii). Plants sprayed with water served as the control. Results showed that fruit and leaves from Ca‐treated plants had increased Ca concentrations. Sprays with B increased status of this microelement in fruit and leaf tissues. Treatments did not affect total and marketable fruit yield, mean berry weight, the number deformed fruit, soluble solids concentration and titratable acidity of fruit at harvest. Fruit sprayed with Ca or B plus Ca were firmer and more resistant to Botrytis rot at harvest and after 3 days of holding at 18°C compared to those of control plots. Moreover, sprays of Ca or B plus Ca increased soluble solids concentration and titratable acidity of fruit after 3 days of holding at room temperature. These results indicate that sprays of CaCl₂ with addition of Tween 20 should be recommended to improve quality and shelf‐life of strawberry fruit, particularly in proecological production where application of fungicides is restricted.     

Effect of Calcareous Soil on Photosynthesis Rate,Mineral Nutrition,and Source‐Sink Ratio of Table Grape

Abstract

Vitis vinifera L. cv Aurora grafted on S.O.4 (medium lime‐tolerance) rootstock was grown in pot with a high‐carbonate‐soil and a low‐carbonate‐soil. The aim of the trial was to check soil effect on some physiological features such as leaf chlorophyll (Chl) concentration and gas exchange, whole‐canopy gas exchange, mineral nutrition, dry matter partitioning, and technological grape parameters. Measurements for whole‐canopy gas exchange were taken using a custom‐built, flow‐through whole‐canopy gas exchange system set up to run continuous, automated, and simultaneous net carbon exchange rate (NCER) readings of four canopies. The most significant findings were: (a) high‐carbonate‐soil decreased leaf and whole canopy photosynthesis, grape yield, and total dry matter production; (b) high‐carbonate‐soil increased the distribution share of dry matter in the trunk and roots, as compared to the low‐carbonate‐soil, and decreased the share of dry matter in the clusters; and (c) lime‐stress conditions affected mineral nutrition, especially P and K concentrations, which were depressed in most of the organs.     

Influence of Loss‐on‐Ignition Temperature and Heating Time on Ash Content of Compost and Manure

Abstract

Loss‐on‐ignition (LOI) is a simple method for determining ash content, and by reciprocation, organic matter content of compost and manure. However, reported ignition temperatures and heating times for LOI measurements vary widely, and this brings into question the accuracy of one specific combination of ignition temperature and heating time over another. This study examined the effect of 42 temperature‐heating time combinations (six ignition temperatures from 400 to 650°C in 50°C increments by seven heating times of 1, 2, 8, 12, 16, 20, and 24‐h) on the ash content of a finished compost and a fresh manure. The experiment included the 550°C for 2‐h method recommended in Test Methods for Evaluation of Compost and Composting. The magnitude of the decrease in ash content due to increase in temperature was not consistent across all heating times. For example, after a 1‐h heating time for compost, ash content was 75.7% at 400°C and 67.5% at 650°C, compared to 69.6% at 400°C and 66.8% at 650°C after 24‐h. Irrespective of heating time, an ignition temperature of 400°C overestimated ash content for both compost and manure compared to the TMECC method. The TMECC method with its moderate temperature and short heating time requirement could reduce energy costs without affecting ash content results.     

Boron fertilization,vesicular‐arbuscular mycorrhizal colonization and growth of citrus jambhiri lush

The role of boron (B) fertilization in the vesicular‐arbuscular mycorrhizal (VAM) colonization and growth of container‐grown Citrus seedlings was evaluated. Citrus jambhiri Lush, seedlings inoculated with Glomus fasciculatum, Glomus etunicatum or non‐inoculated were grown in a sandy loam soil for sixteen weeks. Seedlings were fertilized with 25 ug/ml B applied to the foliage as a mist, to the soil as a solution, or to both the foliage and the soil. Boron applied to the foliage or to the soil significantly increased root exudation of reducing sugars and amino acids two weeks after seedling germination. Subsequently, foliar fertilization with B significantly increased VAH colonization of seedlings relative to the controls. Plants inoculated with G. fasciculatum were larger and had greater VAM development than those inoculated with G. etunicatum. The growth of the noninoculated seedlings was not enhanced by B fertilization. The superior VAH colonization and growth of inoculated seedlings fertilized with B suggests that B stimulates the efficacy of plant fungi symbiosis.     

Impact of Soil Type and Application Rate on the Availability of P Applied as Alum‐Treated Poultry Litter

The purpose of this laboratory incubation study was to assess the solubility of phosphorus (P) in alum‐treated poultry litter (ATPL) when applied to three Virginia soils at equivalent P‐based rates. Three poultry litter sources (one that had received no alum additions and two that had received alum additions) were utilized in the study. These litter sources and monopotassium phosphate (KH₂PO₄) were applied at rates of 66, 132, and 197 mg P kg^?1 with a 0‐P check treatment included for each soil. Soils were incubated for 1 year, and samples were collected at 1, 3, 6, and 12 months after treatment application. Data collected were used to calculate the relative extractability of P applied in the three litter sources. Results indicated that ATPL applications reduced P solubility compared to untreated poultry litter (NPL); this effect was most significant at 1 month after application. However, at 12 months, significant differences in extractable P between NPL and ATPL treatments were limited at the 66 mg P kg^?1 rate. This resulted from continuous decline in the extractability of P applied in the NPL, whereas the extractability of P applied in the ATPL source changed little with time and in some cases increased slightly between the 1‐ and 3‐month sampling periods. Calculated values of relative extractability were influenced not only by litter source but also P application rate, soil type, and incubation time. Therefore, use of relative extractability values as P source coefficients should be done with caution, because experimental protocol can have profound effects on their magnitude.