Factors affecting the concentration of Zn,Fe and Mn in herbage from organic farms and in relation to dietary requirements of ruminants

To obtain a general picture of the herbage zinc, iron and manganese concentrations and their relation to dietary requirements of ruminants on organic farms, we analysed soil and herbage samples from four regions in Norway. The soil median Zn, Fe and Mn concentrations were 0.18, 13 and 0.84 mg/L, respectively. The herbage median (10th–90th percentile) Zn, Fe and Mn concentrations (mg/kg) in herbage in the first cut were 19 (14–34), 50 (36–88), 34 (22–86) and in the second cut 21 (16–37), 84 (52–171) and 66 (36–205), respectively. The results of mixed model analysis of herbage Zn, Fe and Mn indicate that soil pH, soil texture, soil mineral concentration and botanical composition are the most influencing factors. We conclude that Zn, Fe and Mn did not limit plant growth, and that the herbage concentrations, except for Zn, were sufficient to meet the dietary needs of ruminants on organic dairy farms.     

微肥对尖叶菠菜硝酸盐积累的拮抗效应研究

研究了微肥对尖叶菠菜硝酸盐积累的拮抗效应,结果表明:微肥配合尿素施用与单施尿素相比,尖叶菠菜的生物量最多可增加25.77%;硝酸盐含量最多可减少29.74%;硝酸还原酶活性最多可提高28.27%.     

西藏“一江两河”地区洪积土有效微量元素的有效性研究

对西藏“一江两河”地区洪积土微量元素的有效性研究表明，该地区洪积土不缺Ｃｕ，但部分洪积土有效Ｚｎ，Ｆｅ，Ｍｎ不足，影响洪积土有效微量元素含量的因子依次是土壤酸碱度，有机质，ＣＥＣ和ＣａＣＯ３，质地的影响最小，酸碱度和ＣａＣＯ３为负效应，有机质和ＣＥＣ为正效应。     

稀土微肥在金针菇上的应用

介绍了使用不同浓度的稀土微肥拌料按常规栽培金针菇的试验,结果表明:农用硝酸稀土浓度为50 mg/kg时,促进菌丝生长、出菇整齐,产量较对照提高26.1%.用50 mg/kg稀土微肥处理过的金针菇,菌盖小,菌柄长而粗,菌柄基部呈淡黄色至褐色,经济性状优于对照.     

小黑麦子粒中铁、锰、铜、锌含量对氮素反应的品种差异及其类型

采用盆栽试验,以31份具有不同遗传背景的小黑麦品种为材料,设低氮和正常供氮2个氮素水平,探讨小黑麦子粒中铁、锰、铜、锌含量对氮素反应的品种差异及其类型。结果表明: 1）不同供氮条件下,小黑麦子粒中铁、锌含量以正常供氮显著高于低氮条件,锰、铜含量在两个供氮条件下差异不显著;相同供氮条件下,小黑麦子粒中铁、锰、铜、锌含量存在显著的品种差异,变异系数为15.07 %～38.69 %。2） 铁、锰、铜、锌含量对氮素供应的敏感性存在差异,以各小黑麦品种子粒微量元素含量对氮素响应的敏感程度,可将其分为钝感型、中间型和敏感型3种类型。3）相关分析表明,铁、锰含量与粒重相关性不显著,铜、锌含量与粒重呈极显著正相关（相关系数分别为0.45、0.44）;铁、锰、铜、锌含量与子粒中含氮量呈极显著正相关（相关系数分别为0.34、0.55、0.47、0.71）。这些结果可为小黑麦营养品质有利基因的发掘和运用提供参考依据。     

巢湖流域磷肥减量施用对稻麦轮作体系作物产量和品质的影响

【目的】探讨稻麦轮作体系下磷肥减量施用对作物籽粒产量与营养品质的影响,为巢湖流域稻麦轮作体系下磷肥减量增效,作物优质生产提供理论依据。【方法】于2017—2019年在巢湖流域进行磷肥减量施用田间试验,设置5个处理：对照（CK,不施磷）、农户模式（P1,磷用量90 kg P₂O₅·hm^-2）、减磷10%（P2,磷用量81 kg P₂O₅·hm^-2）、减磷20%（P3,磷用量72 kg P₂O₅·hm^-2）、减磷30%（P4,磷用量63 kg P₂O₅·hm^-2）。分析磷肥减量施用对水稻和小麦产量及其构成要素,籽粒蛋白质及组分含量,微量元素及其生物有效性的影响。【结果】与不施磷相比,施磷水稻和小麦的籽粒产量分别显著提高了9.8%—28.3%和56.6%—89.7%。减磷10%和20%处理的水稻和小麦籽粒产量与农户模式无显著差异（P>0.05）,但减磷30%处理的水稻产量显著降低14.4%。与农户模式相比,减磷处理显著影响作物蛋白质、醇溶蛋白和谷蛋白含量,对结构蛋白（清蛋白+球蛋白）无显著影响,减磷20%处理水稻籽粒蛋白质和谷蛋白含量降低2.7%和32.3%,减磷30%处理的水稻和小麦籽粒蛋白质和谷蛋白含量分别降低6.8%和21.9%、48.4%和31.6%。与不施磷相比,施磷同样显著影响水稻和小麦籽粒微量元素含量及其生物有效性。减磷处理较农户模式水稻和小麦籽粒Fe、Cu和Zn含量提高21.2%和19.3%、11.9%和15.8%、14.5%和19.9%;P/Fe、P/Cu和P/Zn摩尔比降低21.6%和26.3%、20.6%和27%、17.7%和21.3%。水稻和小麦籽粒Zn含量随施磷量的降低而线性增加,减磷处理间的作物籽粒Fe、Mn和Cu含量无显著差异。水稻籽粒P/Zn摩尔比随施磷量的降低而降低,减磷处理间籽粒P/Fe、P/Mn和P/Cu摩尔比无显著差异;小麦籽粒P/Fe、P/Mn、P/Cu和P/Zn摩尔比均随施磷量的降低而降低,提高了小麦籽粒Fe、Cu和Zn的生物有效性。【结论】在巢湖流域稻麦轮作区,磷肥减量20%,即磷肥用量由90 kg P₂O₅·hm^-2减至72 kg P₂O₅·hm^-2时仍可保证作物稳产。磷肥减量施用虽在一定程度上降低了籽粒蛋白质含量和谷蛋白含量,但显著提高了微量元素Fe、Cu和Zn的含量和生物有效性。综合考虑,推荐磷肥减量20%为巢湖流域稻麦轮作区实现磷肥增效及作物高产优质生产的磷肥优化管理措施。     

Micronutrients distribution in salt-affected soils of the Punjab in relation to soil properties

Salt-affected soils in arid and semi-arid tracts of the Indian Punjab are prone to deficiency of micronutrients. Nine profiles from alluvial terraces, sand dunes and palaeochannels in the southwestern Punjab were investigated for total and diethylenetriamine-penta-acetic acid (DTPA) extractable Zn, Cu, Mn and Fe. Soil physiography exerted significant influence on the spatial distribution of micronutrients. Total contents varied from 20–78 for Zn, 8–32 for Cu, and 88–466 mg kg^?1 for Mn and 0.82–2.53% for Fe. DTPA-extractable contents varied from 0.10–0.98 for Zn, 0.14–1.02 for Cu, 0.54–13.02 for Fe and 0.82–9.4 mg kg^?1 for Mn. Total contents were higher in fine-textured soil than in coarse-textured soils. Concentration of micronutrients in the surface layer was low and there occurred more accumulation in the Cambic horizon. Organic carbon, pH, clay, silt and calcium carbonate exerted strong influence on the distribution of micronutrients. DTPA extractable Zn, Cu, Mn and Fe increased with increasing organic carbon but decreased with increase in pH and calcium carbonate content. Total micronutrient contents increased with increase in clay, silt and calcium carbonate contents and decreased with increase in sand content.     

GROWTH AND NUTRITION OF YOUNG BEAN PLANTS UNDER HIGH ALKALINITY AS AFFECTED BY MIXTURES OF AMMONIUM,POTASSIUM, AND SODIUM

High concentrations of bicarbonate (HCO^? ₃) cause alkalinity of irrigation water and are associated with suppression in plant growth and micronutrient deficiencies, such as iron (Fe) and zinc (Zn). Because reports indicate that the deleterious effects of alkalinity may be counteracted partially by supplementary potassium (K⁺) or ammonium (NH₄ ⁺) an experiment was designed to evaluate the response of bean plants (Phaseolus vulgaris L.) grown in high alkalinity conditions to varying proportions of NH₄ ⁺, K⁺, or sodium (Na⁺) (as a potential substitute for K⁺). Plants established in a growth chamber were grown in hydroponics for 21 days in solutions containing 5 mM HCO^? ₃ and a total of 5 mM of a mixture of NH₄ ⁺, K⁺, and Na⁺. The proportions of NH₄ ⁺, K⁺, and Na⁺ were designed according to mixture experiment methodology. Total N in all the mixture treatments was maintained at 10 mM by using nitrate (NO^? ₃)-N, thus the NH₄ ⁺:NO^? ₃ ratio varied according to the proportion of NH₄ ⁺ in the mixtures. Alkalinity caused suppression in plant growth and chlorophyll concentration in the younger leaves, whereas excessive NH₄ ⁺ was associated with leaf scorching and decreased leaf expansion. High proportions of K⁺ alleviated alkalinity symptoms and produced higher shoot and root dry mass provided that NH₄ ⁺ was included in the mixture. However, a proportion of NH₄ ⁺ higher than 0.333 in the mixture (>1.66 mM NH₄ ⁺) induced toxicity. The highest shoot dry mass occurred if the NH₄ ⁺:NO^? ₃ ratio was 0.19:0.81 and the NH₄ ⁺:K⁺:Na⁺ proportion was 0.38:0.38:0.24 (1.9 mM NH₄ ⁺ + 1.9 mM K⁺ + 1.2 mM Na⁺). Thus, an improvement in plant growth is achieved when NH₄ ⁺, K⁺, and Na⁺ are blended together, in spite of the high alkalinity treatment imposed. Optimum NH₄ ⁺ was associated with a decrease in solution pH and an increase in shoot Fe and Zn concentration.     

Controlled-release fertilizer of zinc encapsulated by a manganese hollow core shell

Abstract

The distribution of azolla, its growth, and P-deficiency were studied in the Philippines by collecting 232 azolla samples from ponds (33%) and rice fields (67%: 40% with rice and 27% without rice) in 11 regions. The dominant species, coverage, color, healthiness, fertilizer treatment, and use by farmers were recorded. The N and P concentrations in azolla were expressed on an ash-free dry matter basis. The average N concentration was 4.5% and the median 4.5%. The average P concentration was 0.385% and the median 0.332%. Region, species, color, and visual judgment of healthiness were correlated with P concentration. Red Azolla pinnata var. imbricata samples had a lower average P content (n = 42, P = 0.245%) than green samples (n = 41, P = 0.46%). A. microphylla was always green and had significantly higher N and P concentrations than A. pinnata var. imbricata. Nitrogen and P contents were highly correlated (simple correlation coefficient = 0.64, ranking correlation coefficient = 0.73). As the content of P increased, the content of N was likely to approach a plateau. The N concentration at the plateau and the P concentration required to reach this plateau were higher in the A. microphylla-dominated samples than in A. pinnata var. imbricata-dominated samples. When the P concentration corresponding to 90% of the N% plateau was set as the critical concentration for P deficiency, 53% of azolla plants was considered to be P deficient. Soil samples were taken from 66 out of the total number of azolla sampling sites, and their chemical properties were analyzed. Average available soil P content of the soils, where the azolla samples were taken, was higher than the average for the Philippine soils. There was a distinct difference in the content of available soil P (Olsen P) between the soils where A. pinnata var. imbricata was dominant (n = 51) and those where A. microphylla was dominant (n = 8). The average content of available soil P of the former was 28 ppm and the median 12.5 ppm, whereas the average of the latter was 54 ppm and the median 47 ppm. No statistically significant differences were observed in other chemical properties. In soils where A. pinnata var. imbricata was dominant, the simple correlation coefficient between plant P concentration and soil available P content was 0.31 and the ranking correlation coefficient 0.34. The ranking correlation coefficient excluding samples from ponds was 0.54 (n = 42).     

Nutritional and management related interactions with iron-deficiency stress response mechanisms

Iron (Fe) deficiency symptoms develop in many agricultural and horticultural settings and generally occur when susceptible genotypes are grown in calcareous soils where Fe availability is limited. However, in some situations, Fe deficiency develops as a result of biological interactions with factors other than limited available Fe. We review physiological explanations for some factors known to interact with iron-deficiency stress. The discussion includes interactions with macronutrients and micronutrients, management factors such as grazing and companion cropping, and symbiotic nitrogen fixation. We also refer to several field observed interactions with Fe deficiency in soybean [Glycine max (L.) Merr.], where physiological explanations are yet to be identified. These include interactions with seeding rate and application of the herbicide glyphosate on glyphosate tolerant varieties. We believe that elucidation of additional physiological answers for field observations are critical to efficient and economic viability of world food production.