AMELIORATION OF ZINC DEFICIENCY OF CORN IN CALCAREOUS SOILS OF THAILAND: ZINC SOURCES AND APPLICATION METHODS

A variety of zinc (Zn) fertilizer sources are applied with varied responses on calcareous soils in Thailand. Seed treatment is an alternative method to deliver Zn to corn and alleviate Zn deficiency. To address this Zn delivery methods we conducted greenhouse studies on corn grown in three calcareous soils of Thailand to three Zn fertilizer sources [zinc sulfate (ZnSO₄), Zn-ethylenediaminetetraacetic acid (EDTA) and Zn citrate]. We also evaluated effectiveness of soaking corn seed in three concentrations of ZnSO₄ (0.4, 0.8 and 1.6%) prior to planting compared to soil applied methods. Applications of zinc increased the growth, dry matter yield and zinc uptake of corn with few differences observed among the types of fertilizers. Seed soaking with ZnSO₄ solution also increased Zn uptake, growth rate and yield comparable to soil-applied Zn. Seed soaking prior to planting is an effective and efficient method to supply Zn to corn grown in Zn deficient calcareous soils of Thailand.     

Influence of P,Zn and Fe fertilization upon yield and protein quality of Sanilac Navy bean seed

Abstract

Treatments of P, Zn and Fe fertilizers were added to a Zn deficient Wisner silty clay loam soil. Sanilac bean plants were grown as the Zn responsive test crop and tissue samples were taken 5 weeks after planting for early growth and Zn uptake responses. At maturity, yield data were obtained and composite samples of beans were taken for determination of protein quality as evaluated by percentage of N, percentage of crude protein and relative contents of essential amino acids. A growth and Zn uptake response was obtained to ZnSO₄, ZnNTA and FeNTA fertilization at both P levels, while a yield response to the same treatments was obtained only at high soil P (448 kg/ha) levels. The percentage N, percentage crude protein and relative contents of essential amino acids did not change as a result of P, Zn or Fe fertilization even when yields were tripled due to Zn fertilization.     

Preparation and Optimization of Amino Acid Chelated Micronutrient Fertilizer by Hydrolyzation of Chicken Waste Feathers and the Effects on Growth of Rice

For the preparation of amino acid chelated fertilizer, chicken feathers were hydrolyzed with sulfuric acid (H₂SO₄; 6M) and potassium hydroxide (KOH; 6M) separately in the presence of different catalysts. Under acidic conditions, the catalyst zinc sulfate, gave minimum ammonium but a maximum conversion rate of organic nitrogen (N) into amino acids (19% higher than control). Under alkaline conditions, sodium sulfide showed maximum amino acid-N and conversion rate (37% higher than control). The catalyst doses showed a continuous increase in the conversion rate and were highest at 12%. The ratio of 1:3 feathers: hydrolytic agent showed maximum conversion rate. Hydrolytic time had a nonsignificant effect under acidic conditions, but under alkaline conditions a hydrolytic time of 14 h gave the maximum conversion rate. The chelation experiment results showed that the ratios (2:1, 2.5:1, and 3:1) showed almost equal chelation rates, except the 1:1 ratio of hydrolysis product to salt. Iron (Fe), copper (Cu), and manganese (Mn) showed maximum chelation rates under acidic pH, while zinc (Zn) showed maximum chelation rate at an alkaline pH. Temperature and chelation time had a nonsignificant effect on chelation rate. Comparative study results of amino acid chelated Zn and Fe fertilizers, ethylenediaminetetraacetic acid (EDTA) chelated Zn and Fe fertilizers, and zinc sulfate (ZnSO₄) and iron sulfate (FeSO₄) fertilizer foliar application to upland rice showed that a 1/100 dilution of amino acid chelated Zn and Fe fertilizers increased growth parameters from 22–73%, while EDTA chelated Zn and Fe fertilizers caused an increase of 15–63%, and ZnSO₄ and FeSO₄ increased growth parameters from 11–35% over the control. After fertilizer application, increase in chlorophyll contents was 11–17%, 3–6%, and 8–12%, respectively, over control. Therefore, amino acid chelated micronutrient fertilizer is used in small amounts, has a low cost, and high rates of return.     

Agronomic and economic efficiency of ground tire rubber and rubber ash used as zinc fertilizer sources for wheat

The aim of this 2-year field experiment was to investigate agronomic and economic efficiency of ground tire rubber and rubber ash as zinc (Zn) sources for wheat (Triticum aestivum L. cvs. Kavir and Back Cross) compared with a commercial zinc sulfate (ZnSO₄). A similar rate of Zn was used by soil incorporation of 40 kg/ha ZnSO₄, 200 kg/ha waste tire rubber ash, and 1000 kg/ha ground rubber. A no Zn added treatment was also considered as control. All Zn fertilizers significantly increased grain yield of wheat over the control, although effectiveness of rubber ash was greater than the other Zn sources. Wheat plants treated with rubber ash accumulated higher Zn in their grains compared with those treated with ground rubber and ZnSO₄. Tire rubber ash had the highest agronomic and economic efficiency and contained low levels of cadmium (Cd) and lead (Pb). Therefore, it can be used as an economic substitution for commercial ZnSO₄.     

Prediction of residual effects of zinc sulfate on growth and zinc uptake of corn plants using three zinc soil tests

Abstract

A significant portion of chemical zinc (Zn) fertilizers applied to calcareous soils is not absorbed by the first crop and may, therefore, affect the growth and chemical composition of the subsequent crops. This is called the residual effect of Zn. Soil tests may be used to predict such effects. The present experiment was conducted to study the residual effects of zinc sulfate (ZnSO₄) on the second crop of corn (Zea mays L.) grown on selected highly calcareous soils of Iran and to compare the suitability of three soil tests for prediction of the effects. Twenty highly calcareous soils of southern Iran (16–58% calcium carbonate equivalent; pH 7.9–8.5), previously treated with three levels of Zn (0, 10, and 20 mg Zn/kg as ZnSO₄) and under one crop of corn, was used in greenhouse to grow a second crop of corn without additional Zn fertilizer but with uniform application of nitrogen (N), phosphorus (P), and iron (Fe). Soils were sampled before the second crop and extracted with three Zn extradants, DTPA, EDTA‐(NH₄)₂CO₃, and EDTA. Dry weight of plant tops and Zn concentration and uptake after eight weeks under the greenhouse conditions were used as the plant responses to residual Zn. Statistical analyses including F‐test and multiple regression equations showed that the overall effect of previously‐applied Zn on dry matter was nonsignificant, but Zn concentration and uptake were significantly increased. The three soil tests predicted the Zn concentration and uptake equally well. Moreover, DTPA and EDTA soil tests could predict the dry matter of plants at the highest level of previuosly‐applied Zn (20 mg Zn/kg), especially when selected chemical properties of soil, namely, calcium carbonate equivalent or organic matter content, were considered in the regression equations.     

Response of corn to plowed‐down and disked‐in Zn as zinc sulfate

Abstract

A field investigation was conducted to compare the efficacy of plowed‐down and disked‐in Zn as ZnSO₄.H₂O in correcting Zn deficiency of corn (Zea mays L.). The soil, Buchanan fine sandy loam, was nearneutral in pH and contained 0.7 ppm of EDTA‐extractable Zn and 1.4 ppm of dilute HCl‐H₂SO₄ extractable P. Application of 6.72 kg Zn/ha as ZnSO₄.H₂O corrected Zn deficiency of corn plants on the soil. Corn grain yields and Zn concentrations in tissue samples indicated that the plowed‐down and disked‐in Zn were about equally effective in correcting Zn deficiency where the level of Zn application was 6.72 kg/ha.     

氮锌互作对水稻产量及籽粒氮、锌含量的影响

为探明氮锌互作对水稻产量及氮、锌含量的影响,以镇稻11号为供试材料,在大田条件下研究了2个氮肥用量（N 200、300 kg/hm2）下6个施锌水平（ZnSO47H2O 0、10、25、50、100、150 kg/hm2） 对水稻产量及成熟期植株氮、锌浓度及累积量的影响。试验结果表明: 在本试验条件下,锌肥的施用对水稻产量的增加不显著,但施锌能显著提高水稻各部位的锌浓度和籽粒锌累积量,并能提高水稻籽粒的氮浓度和粗蛋白含量,且表现出随施锌量的增加籽粒的氮浓度和粗蛋白含量增加的趋势; 高施氮量有利于水稻的增产及对锌的吸收与累积。因此,氮锌配施具有增加籽粒锌富集和提高蛋白质含量的双重效益。     

EFFECT OF ZINC NUTRITION ON GROWTH,YIELD, AND QUALITY OF FORAGE SORGHUM IN RESPECT WITH INCREASING POTASSIUM APPLICATION RATES

A two-year field study was conducted to determine the effect of two zinc (Zn) levels [0 and 10 kg zinc sulfate (ZnSO₄) ha^?1] in respect with four potassium (K) levels (0, 20, 40 and 60 kg K₂O ha^?1) on growth, yield and quality of forage sorghum. The soil of the experimental field was loamy sand (Inceptisol), carrying 70, 08, 77, and 0.51 mg nitrogen (N), phosphorus (P), K, and Zn kg^?1 soil, respectively. Increasing K levels significantly improved most of the growth, yield, and quality attributes gradually irrespective of the Zn levels. Zinc applied at 10 kg ZnSO₄ ha^?1 proved significantly better than no zinc application at various K application rates. The benefit of zinc application increased progressively with increasing K rates for most of the parameters studied, indicating significant response of the crop to positive K × Zn interaction in plants in respect with K and Zn application to the soil. Accordingly, 60 kg K₂O ha^?1 applied with10 kg ZnSO₄ ha^?1 boosted most of the attributes maximally. It resulted in about 20–40% increase in growth attributes, 25% increase in fresh matter yield, 36–38% increase in dry matter yield, and 38% increase in protein yield compared to the comparable K level applied without zinc. It also enhanced N uptake by 38%, P uptake by 5–19%, K uptake by 40–42%, and Zn uptake by 114–144%. Across the K rates, application of 10 kg ZnSO₄ surpassed no zinc application by 30–35% in N uptake, by 8–15% in P uptake, by 33–36% in K uptake, by 120–140% in Zn uptake, by 19–21% in fresh matter yield, by 29–31% in dry matter yield, and by 30–34% in protein yield.     

Effects of ZnSO4 and Zn‐EDTA applied by broadcasting or by banding on soil Zn fractions and Zn uptake by wheat (Triticum aestivum L.) under greenhouse conditions

Zinc biofortification of staple food crops is essential for alleviating worldwide human malnutrition. Agronomic interventions to promote this should include fertilizer selection and management. A chelated Zn source, Zn‐EDTA, and an inorganic Zn source, ZnSO₄ × 7 H₂O, were applied either by banding or by broadcasting in soil, and Zn fractions in soil and Zn uptake by wheat were determined in a pot experiment. Compared to ZnSO₄ × 7 H₂O, Zn‐EDTA produced higher Zn concentration in grain regardless of application method and even at a lower application rate. Residual Zn fraction was the largest Zn fraction with both ZnSO₄ and Zn‐EDTA amendment. ZnSO₄ banded in soil caused Zn fractions to be restricted to the Zn‐amended soil band and resulted in lower grain Zn concentrations than did broadcast ZnSO₄. Planting wheat slowed Zn fixation by promoting the maintenance of a high concentration of Zn fraction loosely bound to organic matter (LOM‐Zn) in soil. Zn‐EDTA was a better Zn source for Zn biofortification of wheat than was ZnSO₄.     

施锌对小麦开花后氮、磷、钾、锌积累和运转的影响

为明确大田条件下施锌对小麦地上部器官氮、磷、钾、锌的积累量和转移量的影响,2001～2002年开展了田间试验。试验以专用强筋小麦(8901-11)和普通小麦(4185)两个冬小麦品种为材料,包括4个施锌水平(分别为施ZnSO4.7H2O.0、11.25、22.5和33.75.kg/hm2)。结果表明,各器官中Zn的含量变化在4.14～54.18.mg/kg,刚开花时及灌浆前期的含量以子粒>穗壳>叶片>茎秆,至接近成熟时则以子粒>叶片>穗壳>茎秆。每生产100.kg小麦子粒需要吸收Zn的范围在4.40～5.20.g之间。小麦成熟时吸收的Zn约为N或K2O的1/800～1/700,为P2O5的1/500～1/300。施锌后小麦各器官氮、磷、钾、锌的积累量及开花后向子粒的运转量增加,但施锌过多,这些营养元素的吸收、积累和运转反而受到抑制。4185开花前吸收氮和磷的能力较强,而8901-11开花后吸收氮和磷的能力较强;而吸收钾和锌的能力与吸收氮和磷的情况相反。8901-11氮、磷、钾、锌的积累量基本随施锌量增加而提高,以施硫酸锌22.5～33.75.kg/hm2的积累量最高;而4185以施硫酸锌11.25.kg/hm2的积累量最高。因此,在施用大量元素的基础上,普通小麦以施硫酸锌11.25.kg/hm2为宜,而强筋小麦以施硫酸锌22.5～33.75.kg/hm2为宜。     

Effects of Green Manures and Zinc Fertilizer Sources on DTPA-Extractable Zinc in Soil and Zinc Content in Basmati Rice Plants at Different Growth Stages

Rice is very sensitive to low zinc(Zn) supply in submerged paddy soils and Zn deficiency is one of the major limiting factors in determining rice production in India. A field experiment was conducted during the summer-rainy seasons of 2009 and 2010 at the research farm of the Indian Agricultural Research Institute, New Delhi, to determine the effects of summer green manure crops and Zn fertilizers on diethylenetriaminepentaacetic acid(DTPA)-extractable(available) Zn concentration in soil and total Zn content in Basmati rice cultivar Pusa Basmati 1 at periodic intervals. Summer green manure crops included Sesbania aculeata(Dhaincha),Crotalaria juncea(Sunhemp), and Vigna unguiculata(Cowpea) and the Zn fertilizers used were ethylenediaminetetraacetic acid(EDTA)-chelated Zn, ZnSO_4·7H_2O, ZnSO_4·H_2O, ZnO, and ZnSO_4·7H_2O + ZnO. Beneficial effects of summer green manure crops and Zn fertilizers on DTPA-extractable Zn concentration in soil and total Zn content in dry matter of Basmati rice at periodic intervals were observed, with significant increases in all the determined parameters, in comparison with those in the control(no Zn application or summer fallow). The rate of increase varied among summer green manure crops and Zn fertilizers during both years. Among the summer green manures, incorporation of S. aculeata led to a significant increase in mean Zn content in Basmati rice grain and straw when compared with C. juncea, V. unguiculata, and summer fallow treatments. Among the Zn fertilizers, significant increases in Zn content in Basmati rice dry matter and DTPA-extractable Zn concentration in soil during various growth stages of the plant were recorded with EDTA-chelated Zn application, followed by the application of ZnSO_4·7H_2O, ZnSO_4·H_2O, ZnSO_4·7H_2O + ZnO, ZnO,and no Zn. The highest mean Zn content in Basmati rice grain and straw was recorded with EDTA-chelated Zn application in 2009 and 2010, respectively. The application of ZnSO_4·7H_2O was the second best treatment after EDTA-chelated Zn; however, it was statistically inferior to EDTA-chelated Zn. The lowest values were recorded with the control(no Zn application) during both years of study. The amount of Zn concentration in soil was found to be significantly positively correlated with the Zn content in Basmati rice dry matter during both years. Significantly higher levels of residual fertility in soil after the harvest of Basmati rice were observed with application of EDTA-chelated Zn and incorporation of S. aculeata when compared with those of other Zn sources and summer green manures.     

Effect of Zn binding to phytate and humic substances on its uptake by wheat (Triticum durum L.) as affected by carbonates and Fe oxides

Although complexation with soil organic matter may improve zinc (Zn) bioavailability to plants, the effect of Zn sorbent surface on the use of complexed Zn by plants remains unknown. The objective of this research was to elucidate how Zn complexation with humic substances (HS) and phytate affects the uptake of Zn by wheat plants depending on the main sorbent surface in growth media, i.e., carbonates and Fe oxides. To this end, two pot experiments were performed, one using Fe oxide-coated siliceous as the siliceous growth medium sand and the other using a mixture of calcareous sand and siliceous sand as the calcareous growth medium. Each experiment involved three Zn sources, Zn-HS complex, Zn phytate, and ZnSO₄. All sources were applied with surface irrigation at two Zn rates (0.25 and 2 mg kg^-1 growth medium). The Zn-HS complex significantly increased Zn uptake by plants in both media, relative to the other two Zn sources, but no significant difference was observed between Zn phytate and ZnSO₄. In the calcareous medium, Zn-HS complex and Zn phytate resulted in significantly higher dry biomass yields of wheat than ZnSO₄. In the siliceous medium, spike and shoot dry biomass yields with Zn-HS complex at the low rate and Zn phytate at both rates were not significantly different from those with ZnSO₄ at the high rate. After harvest, approximately 50% of the Zn applied as Zn-HS complex remained extractable by diethylenetriaminepentaacetic acid (DTPA), while this proportion was less than 20% for the other Zn sources. Thus, Zn-HS complex and Zn phytate are sources of available Zn for plants, and they are more effective than ZnSO₄ in increasing plant growth, particularly when carbonates are the main Zn sorbent surface.     

Influence of water solubility of granular zinc fertilizers on plant uptake and growth

Abstract

Zinc (Zn) fertilizer application has increased during the past three decades. This increase has created the need for more information regarding the availability and agronomic effectiveness of Zn containing fertilizers because differences of opinions exist relating the relationships between Zn water solubility and plant availability. Plant availability of eight commercialized Zn fertilizer materials having different water solubilities was measured under greenhouse conditions. Corn (Zea mays L.) plants were grown for 40 days in a soil (loamy, mixed, mesic arenic Ustollic Haplargid) amended with lime to two pH's: 6.3 and 7.4. To evaluate the effect of pH, some Zn fertilizers were used at both soil pH levels while all Zn fertilizers were used in the pH 7.4 soil. The experimental design was a factorial combination of pH, Zn fertilizers, and Zn rates of 0,2.1,4.2,8.4 mg Zn kg^?1 soil. Dry matter production and Zn uptake increased significantly when the soil pH decreased from 7.4 to 6.3. The highest dry matter production was obtained with ZnSO₄ (ZnSO₄ H₂O, 99.9% total water soluble Zn), Zn20 (Zn oxysulfate, 98.3% total water soluble Zn), and Zn27 (Zn oxysulfate, 66.4% total water soluble Zn). While ZnFe (Zn iron ferrite, 0.3% total water soluble Zn), ZnK (Zn oxide, KO61, 1% total water soluble Zn), and ZnOS (Zn oxysulfate, 0.7% total water soluble Zn) were less effective followed by Zn40 (Zn oxysulfate, 26.5% total water soluble Zn) and ZnOxS (Zn oxysulfate, 11% total water soluble Zn). The same trend was observed for Zn concentration and uptake. Regression correlations showed that the higher the water solubility, the more effective the Zn fertilizer in increasing dry matter production. Assuming that 5 to 10 kg Zn ha^?1 are the rates commonly recommended, about 50% water soluble Zn is required to adequately supply the crop's needs. Lower fertilizer rates were needed as Zn solubility increased. The cadmium (Cd) and lead (Pb) concentrations and uptakes in corn forage were not significant for any of the sources and rates.     

Effect of high rates of zinc on several crops grown on an irrigated plainfield sand

Abstract

A field experiment was conducted to determine whether Zn applied for pathogen control could accumulate to a level which would be toxic to snapbeans, cucumbers, or corn. Zinc sulfate (ZnSO₄) was applied at rates varying from 0 to 363 kg Zn/ha on a Flainfield loamy sand to approximate 3, 9, 27 and 81 years of fungicidal treatment.

Even at the high rate of Zn, yields of snapbeans, cucumbers, or corn generally were not reduced. As rates of applied Zn increased, there was a corresponding increase in the level of Zn in the leaf tissue of all crops grown. At the high Zn rate, snapbean and cucumber leaf tissue accumulated over 350 ppm Zn. Available soil Zn was extracted with 0.1N HCl, EDTA, or DTPA. Highly significant correlations were observed between the Zn removed by each extractant and plant tissue Zn, thus, indicating that the various extractants were equally effective in predicting Zn uptake.

Very little downward movement of Zn was observed. Two and one‐half years after application, the Zn had leached to a depth of only 30 cm in the soil profile at the higher Zn rates.

These data indicate that application of Zn‐containing fungicides and bactericides should not cause a Zn toxicity problem on the Plainfield sand in the foreseeable future.     

Navy bean yield and maturity response to nitrogen and zinc 1

Dry bean (Phaseolus vulgaris L.) generally responds to nitrogen (N) fertilizer with increased yields, but N can delay maturity and cause yield and quality losses from early fall frost. Maintaining adequate zinc (Zn) nutrition in bean promotes earlier maturity. This study was conducted to determine if Zn application can overcome maturity delays possible with the N recommended for high bean yields. Three zinc sulfate (ZnSO₄) treatments (0 Zn, 5.6 kg Zn/ha banded adjacent to the row, and 11.2 kg Zn/ha broadcast and incorporated) were applied in combination with five N rates (0, 45, 90, 134, and 179 kg/ha). Whole plants were sampled at the R1 growth stage (onset of flowering) and analyzed for N and Zn content. Maturity was estimated by determining the percentage of mature pods at the R8‐R9 growth stage. Yields were estimated by harvesting 12.2 m of row at maturity. Zinc fertilization generally increased mature‐pod percentages with banded Zn producing the most consistent response. Zinc did not consistently affect bean yield. Yield and mature‐pod percentage generally increased and decreased, respectively, with increasing N rate. Whole‐plant N concentrations increased linearly with increasing N rate but did not differ among Zn treatments. Mean plant Zn concentrations were increased by Zn fertilizer and related well with mature‐pod percentage means. In situations of high available N, short growing seasons, or with late planting, Zn applications can reduce the risk of crop losses from early fall frost.     

Effects of Forms and Rates of Zinc Fertilizers on Cadmium Concentrations in Two Cultivars of Maize

Abstract

A pot experiment was conducted to investigate the effects of three soluble zinc (Zn) fertilizers on cadmium (Cd) concentrations in two genotypes of maize (Zea mays): Jidan 209 and Changdan 374. Zinc fertilizers were added to soil at four levels: 0, 80, 160, and 240 mg kg^?1 soil as nitrate [Zn(NO₃)₂], chloride (ZnCl₂), and sulfate (ZnSO₄). Cadmium nitrate [Cd(NO₃)₂] was added to all the treatments at a uniform rate equivalent to 10 mg kg^?1 soil. The biomass of maize plants was increased with the application of three zinc fertilizers, of which Zn(NO₃)₂ yielded more than others. Under ZnCl₂ treatment, plant growth was promoted at the lower level and depressed at the higher one. All the three fertilizers decreased Cd concentration in shoots in comparison with treatments without Zn, but there were variations with different forms, especially in plants treated with Zn(NO₃)₂, which had the minimal value. The orders of average Cd concentration in shoots with different zinc fertilizers were ZnSO₄>ZnCl₂>Zn(NO₃)₂ for Jidan 209 and ZnCl₂>ZnSO₄>Zn(NO₃)₂ for Changdan 374, respectively (P<0.001). There was no significant difference between ZnSO₄ and ZnCl₂ treatments. The lowest Cd concentration in shoots was found in the 80‐mg‐kg^?1 soil or 160‐mg‐kg^?1 soil treatment. Cadmium concentration in roots in the presence of ZnCl₂ was the lowest and under ZnSO₄ the highest. The mechanism involved needs to be studied to elucidate the characteristics of complexation of Cl^? and SO₄ ^2? with Cd in plants and their influence on transfer from roots to shoots.     

Effects of nitrogen fertilization method and tillage system on squash growth,nutrient uptake and fruit yield

Abstract

Squash, cv Dixie, grown on a Lakeland sand was subjected to factorial combinations of 3 tillage systems and 2 N application methods during 1979 and 1980. Fruit yield was greatest with a combination of moldboard plow tillage and application of 22 kg N/ha preplant and 18 kg/ha increments of N by fertigation 2, 3, 4, 5 and 6 weeks after planting. Plant growth and nutrient uptake were greatest and N available for potential contamination of the ground‐water was least with subsoil‐bed tillage and N application by fertigation. Disc harrow tillage with 67 kg N/ha preplant and 45 kg N/ha 4 weeks after planting resulted in 42% less yield, 61% less plant growth, 29 to 64% less nutrient uptake and more than 5 times as much N available for potential contamination of the groundwater as the best practices.     

Zinc concentration of navy bean seed as affected by rate and placement of three zinc sources

Increased zinc (Zn) concentration in seed may sometimes improve human health. The influence of rate and placement of three Zn sources (ZnEDTA, ZnSO₄, and Rayplex‐Zn) on Zn concentration in navy bean (Phaseolus vulgaris L.) seed grown on a Calciaquoll was studied in the greenhouse. Application of 4 and 8 mg Zn/kg mixed throughout the soil increased seed Zn concentration by approximately 60 and 68%, respectively, and the responses were similar with the three Zn sources. The mixed‐throughout‐the‐soil ZnEDTA, ZnSO₄, and Rayplex‐Zn treatments applied at 8 mg Zn/kg reduced seed phosphorus (P) concentration by 10,13, and 15%, respectively. The corresponding reductions with 4 mg Zn/kg were 10, 8, and 13%, respectively. Banding ZnEDTA, ZnSO₄, and Rayplex‐Zn at 4 mg Zn/kg in 17‐cm‐long, 3‐cm‐deep bands reduced seed Zn concentration by 8, 34, and 31 % compared to their mixed‐throughout‐the‐soil counterparts. A significant Zn source x placement interaction resulted from marked reduction in Zn uptake as a result of banding ZnSO₄ and Rayplex‐Zn. Banding of ZnSO₄ and Rayplex‐Zn in calcareous soils is less likely to increase the Zn concentration of navy bean seed than is banding of ZnEDTA.     

Effectiveness of three different zinc fertilizers and two methods of application for the control of “little‐leaf’ in peach trees in south texas

Abstract

Fall soil treatments of ZnEDTA and ZnSO₄ at three increasing rates of 32.2, 64.4, and 128.8 g Zn/tree, and one, two, or three spring foliar treatments of NZN (0.35 g Zn/tree application) replicated four times in a randomized complete block design were tested to find the most effective Zn source, method and rate of application, and economical method for controlling Zn deficiency in three year old ‘Earligrande’ peach trees from 1989 to 1990. The Zn fertilizers had no statistical influence on the soil pH change. The high rates of ZnSO₄, NZN, and ZnEDTA produced equal chlorophyll contents and had no statistical difference in tree appearance. Neither those trees which received three foliar applications of NZN nor those that received the high ZnEDTA soil treatment showed Zn‐deficiency symptoms other than a few chlorotic leaves on top of the trees as a result of Zn being a non‐mobile element. A fourth NZN application, or a delay in initiation of the three NZN spray schedule, would be necessary to compensate for lack of Zn late in the season. All soil applied fertilizers increased the Zn soil content. Zinc EDTA at 128.8 g Zn/tree significantly increased the foliar Zn and chlorophyll content of the treated trees. However, the use of ZnEDTA was not economical. The Control 2‐treatment trees which represented the standard practice in the orchard, had to continuously produce new leaves to replace those lost to peach rust. As a result, these trees were more Zn deficient than the high ZnEDTA‐treatement trees because Zn had to be continuously replaced while those trees with complete leaf compliments only had to obtain enough Zn for new terminal growth. Prevention of rust‐induced defoliation showed the importance of maintaining healthy trees with a full leaf canopy throughout the entire growing season. Three applications of NZN at 0.35 g Zn/tree gave excellent tree response and was the most cost effective treatment.     

Effect of summer green manuring crops and zinc fertilizer sources on productivity,Zn-uptake and economics of basmati rice

Field experiments were conducted for two consecutive years on basmati rice (Oryza sativa L.) during summer and rainy seasons (April–November) of 2009 and 2010 in a sandy clay-loam soil (typic Ustochrept) at the research farm of Indian Agricultural Research Institute, New Delhi. The aim of this study was to determine the influence of zinc fertilizer sources [ethylenediamenetetraacetic acid (EDTA)-chelated zinc (Zn; 12% Zn), zinc sulfate heptahydrate (ZnSO₄.7H₂O; 21% Zn), zinc sulfate monohydrate (ZnSO₄.H₂O; 33% Zn), zinc oxide (ZnO; 82% Zn), and ZnSO₄.7H₂O + ZnO (50% + 50%)] and summer green manuring crops [Sesbania aculeata, Crotalaria juncea and Vigna unguiculata] on productivity, Zn-uptake and economics of basmati rice. Among the summer green manuring crops, Sesbania aculeata accumulated highest amount of total dry matter, 5.46 and 5.77 t ha^?1 during 2009 and 2010, respectively. Incorporation of Sesbania aculeata also led to a significant increase in grain, straw and biological yields, Zn content and uptake and economics of succeeding basmati rice. With the incorporation of Sesbania aculeata, grain and straw yields of basmati rice was 4.89, 5.56 and 9.04, 10.21 t^?1 ha during 2009 and 2010, respectively. Among the Zn fertilizer sources, EDTA-chelated Zn (12% Zn) was found to be the best with respect to grain, straw, and biological yields, Zn content and uptake and economics. Application of EDTA-chelated Zn (12% Zn) recorded the highest basmati rice grain (5.15 and 5.76 t ha^?1) and straw yields (9.30 and 10.48 t ha^?1) compared to control (no Zn application), which produced 4.09 and 4.75 t ha^?1 of grain and 8.13 and 9.39 t ha^?1 of straw yields, respectively, during 2009 and 2010. Highest Zn concentration in grain and straw and its uptake was recorded with Sesbania aculeata incorporation compared with Crotalaria juncea, Vigna unguiculata and summer fallow. Highest total Zn uptake in basmati rice was recorded with EDTA-chelated Zn (12% Zn) application, followed by ZnSO₄.7H₂O (21% Zn), ZnSO₄.H₂O (33% Zn), ZnSO₄.7H₂O + ZnO (50% + 50%), ZnO (82% Zn), and control (no Zn application). Sesbania aculeata incorporation and EDTA-chelated Zn (12% Zn) treatments were found a better combination with respect to basmati rice productivity. The best economical returns were obtained with Sesbania aculeata incorporation and ZnSO₄.7H₂O (21% Zn) combination. Thus, adequate Zn fertilization along with green manure crop incorporation can lead to higher productivity of basmati rice.