影响山核桃林地土壤生产性能的主要肥力因子及其临界区间

【目的】土壤养分是植物生存的必要条件,探讨山核桃(Carya cathayensis Sarg.)主产区林地土壤肥力因子及其对土壤生产性能的影响,为山核桃的栽植和可持续发展、土壤培肥提供科学依据。【方法】在浙江省山核桃主产区,随机选择58个典型乡镇的山核桃林采集土样,测定了pH、有机质、碱解氮、有效磷、速效钾、有效钙、有效镁、有效铁、有效锰、有效铜、有效锌、有效硼12个肥力因子水平,运用主成分分析和回归分析方法,分析了它们对山核桃生长、感病等级、产量等级的影响以及丰缺临界区间。【结果】主成分分析前5个因素(PC1、PC2、PC3、PC4、PC5)的累计贡献率达78.49%。PC1的主要荷载为土壤pH、有效钙和有效镁含量,PC2的主要荷载是微量元素和有效磷含量,PC3是有机质和碱解氮含量,PC4和PC5分别是有效硼和速效钾含量。林分生长性状中,生长势等级与pH、速效钾、有效钙、有效镁、有效铜、有效锌显著负相关(P <0.01),干腐病感病等级与pH、有效钙、有效镁显著负相关(P <0.01),产量等级与pH、有效钙、有效镁、有效磷、有效锌显著正相关(P <0.01)。回归模型分析得出,土壤pH、速效钾和有效钙、有效镁、有效铜、有效锌是当前栽培措施水平下影响山核桃生长的关键土壤肥力因子。综合评价后发现,研究区现有约57%的山核桃林地土壤综合肥力低于平均水平。【结论】对山核桃林地土壤生产性能影响最大的因素是土壤pH、有效钙和有效镁含量,其次是微量元素和有效磷含量,有机质、速效钾含量也有一定的影响。山核桃主产区的林地土壤关键指标丰缺范围:pH 5.19~5.70、速效钾87~129 mg/kg、有效钙817~1374 mg/kg、有效镁93~145 mg/kg、有效铜1.36~4.39 mg/kg、有效锌0.78~2.33 mg/kg。     

Impacts of biochar and processed poultry manure,applied to a calcareous soil,on the growth of bean and maize

Direct use of poultry manure on agricultural lands may cause environmental concerns, so there is a need to establish the suitability of the application of biochar derived from poultry manure for calcareous soil chemical properties and plant growth. The purpose of this study was to evaluate the effects of processed poultry manure (0, 5, 10 and 20 g/kg) and its biochar (0, 2.5, 5, 10 and 20 g/kg) on soil chemical properties of a calcareous soil and growth of bean (Phaseolus vulgaris) and maize (Zea mays) plants. In the incubation experiment, both processed poultry manure (PPM) and biochar decreased pH and the concentration of plant‐available Fe of soil but increased plant‐available P, Zn, Cu and Mn concentrations. PPM and biochar increased the concentrations of exchangeable cations (K, Ca and Mg) in soil. PPM and biochar applications increased the growth of maize and bean plants. PPM and biochar resulted in increased concentrations of N, P, K, Ca, Fe, Zn, Cu and Mn in bean plants. In maize plants, PPM and biochar applications increased the N, P, K, Zn, Cu and Mn but decreased the Ca and Mg concentrations. Results of this study reveal that poultry manure biochar can be used effectively for agricultural purposes.     

Distribution of aluminum in black spruce saplings growing on two New Brunswick forest soils with contrasting acid sulfate sorption

Two adjacent soils with contrasting sulfate sorption were examined in terms of (i) water-soluble and ion-exchangeable Al, Fe, Ca, Mg, K, Mn and Zn, (ii), water- and bicarbonate-extractable sulfate, (iii) Truog-extractable P, (iv) dithionite-extractable Al, Mn and Fe and (v) treatment response to irrigation with simulated acid precipitation. The biomass of 8 year old black spruce saplings growing on the soils, and the distributions of Al, Fe, Ca, Mg, K, Mn, P and Zn within these plants, were also examined. The soils were well to moderately-well drained, with the mineral soil exposed by site preparation prior to planting. The exposed soil underneath individual saplings was treated with acid sulfate solutions (75 mm containing 2 to 50 mg L^?1 H₂SO₄) applied during each of three consecutive growing seasons. The results indicate that Al, much like Fe, Ca, Mn and Zn, accumulated with time in the foliage, but K, Mg and P were highest in young plant tissues. Much of Al and Fe taken up remained in the fine roots. Aluminum uptake increased with the amount of dithionite-extractable Al (free Al oxide) in the soil. Growth of the black spruce saplings was not visibly affected by readily accessed Al in each soil, or by acid irrigation.Instead, growth was restricted by factors other than soil Al and acid irrigation in spite of (i) low soil pH, (ii) high levels of exchangeable Al, and (iii) high levels of Al in fine roots. Sulfate retention across and within the two soils was positively correlated with free Al oxide. The two soils responded to acid irrigation by accelerated silicate weathering and enhanced ion leaching. Sulfate sorption reduced these effects.     

Effects of acid rain on ion leaching in a danish forest soil

The mobility of major cations (H⁺, ammonium, Al, Ca, Na, Mg, K, Fe), heavy metals (Mn, Zn, Ni, Cd) and anions (chloride, sulphate and nitrate) was studied in the laboratory in an acidified brown soil from a Norway spruce forest. Lysimeters containing undisturbed soil columns of the A-horizon and the A- plus B-horizon were watered with 540 mm of throughfall precipitation collected in situ, either directly (pH 3.6) or adjusted to pH 3.3 or 2.8. The pH 3.3 treatment increased leaching of Mn and Cd from the B-horizon. The pH 2.8 treatment increased leaching of ammonium, Na, Ca, Mg, K, Mn, Zn and Cd from the A-horizon and ammonium, Al, Na, Ca, Mg, K, Mn, Zn and Cd from the B-horizon. Fe leaching from the A-horizon was decreased by both acidic treatments, and the pH of the leachates was not significantly affected. Sulphate retention was 138-161 meq m^?2 yr^?1 by all treatments. Due to experimental conditions nitrate leaching was observed in all lysimeters.     

攀西烟区紫色土pH值与土壤养分的相关分析

对四川攀西烟区有代表性的30个紫色土样品的pH值、有机质及有效养分含量进行了测定。结果表明，攀西烟区紫色土的pH值在5．13～8．14范围内，有半数左右的土壤偏碱性；有机质、碱解氮、有效锌和有效锰的含量均随pH值的升高而降低，交换性钙的含量随pH值的升高而升高，而pH值与速效磷、速效钾、交换性镁、速效铜、速效硼间的相关性则不显著。烟区紫色土的有机质和碱解氮含量偏低，速效磷、速效钾含量中等，交换性钙、交换性镁含量丰富；部分pH值较高的土壤可能会缺乏铜、锌等微量元素；在不同pH值的土壤上硼营养均严重亏缺，建议生产中增施硼肥。     

Inoculation of ‘Golden Delicious’ Apple Trees on M9 Rootstock with Azotobacter Improves Nutrient Uptake and Growth Indices

ABSTRACT

Roots of young ‘Golden Delicious’ apple on M9 rootstock were inoculated with four strains of Azotobacter chroococcum, which were isolated from various soils. Effects of these strains in combination with different levels of nitrogen (N) fertilizer and compost on plant growth and nutrient uptake were studied over two seasons. Therefore, a factorial arrangement included four strains of A. chroococcum, two levels of N-fertilizer (0 and 35 mg N kg^?1soil of ammonium nitrate) and two levels of compost (0 and 12 g kg^?1 soil of air-dried vermicompost). Among the four strains, AFA₁₄₆ was the most beneficial strain, as it increased leaf area, leaf potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and boron (B) uptake and root N, phosphorus (P), potassium (K), Mn, and Zn. The combination of AFA₁₄₆ strain, compost and N fertilizer increased leaf uptake of Ca, Mg, Fe, Mn, Zn, and B, and root uptake of P, K, Ca, Mg, Mn, and copper (Cu), and root dry weight.     

Correlations Between Soil Exchangeable Ca2+, Mg2+, K+ and Foliar Nutrient Concentrations in Mature Biological Olive Groves (Olea europaea L., cv. ‘Chondrolia Chalkidikis’)

Leaf and soil samples were taken and analyzed from two mature biological olive groves (Olea europaea L., cv. ‘Chondrolia Chalkidikis’), in Thessaloniki, Macedonia, Northern Greece, in order to determine the correlations between soil exchangeable cations and foliar calcium (Ca), magnesium (Mg) and potassium (K) concentrations, and the interrelations among leaf nutrients. Τhe nutritional requirements of trees for both biological groves were exclusively based on patent kali supply and nutrient recycling (via pruning material and weed cut recycling). Foliar K, Ca and Mg were positively correlated with soil exchangeable K, Ca and Mg, in the 40–60 cm layer, then in the 20–40 cm layer. Synergistic uptake mechanisms among Ca²⁺, Mg²⁺ and K⁺ probably exist. Leaf N was negatively correlated with foliar K, and positively with leaf Ca, Mg and manganese (Mn). Foliar P was negatively correlated with leaf Ca, Mg and Mn, while foliar Ca was positively correlated with leaf Mg and Mn. Foliar Mg was positively related with leaf Mn. High phosphorus (P) may decrease leaf Ca, Mg and Mn. Enhanced Ca may increase leaf Mg and Mn, while high Mg may also enhance foliar Mn. Finally, based on the determination of foliar nutrient concentrations, the nutritional requirements of olive trees in Ca, Mg, K, P, Fe, Zn were sufficiently (or over-sufficiently) satisfied. However, additional organic fertilization is needed, in order to achieve optimum levels of N, B and Mn (since their foliar concentrations were slightly insufficient). The correlations between leaf and soil exchangeable Ca, Mg and K, as well as among foliar nutrients should be taken into consideration, in order to achieve successful organic fertilization for mature biological olive groves, and to avoid nutritional imbalances and disorders.     

Growth of Cocoa Planted on Highly Weathered Soil as Affected by Application of Basalt and/or Compost

Oxisols, which are highly weathered, occupy a large area of Malaysia. These soils are infertile because of low pH, calcium (Ca), magnesium (Mg), and potassium (K) levels but high aluminum (Al) content. The infertility can be ameliorated by applying soil amendments. A study was conducted to determine the effects of basalt and/or rice husk compost application on cocoa growth planted on an Oxisol. The results showed that either basalt or rice husk compost and their combinations were effective ameliorants. Basalt application increased soil pH and exchangeable Ca and Mg while decreasing exchangeable Al. Accordingly, soil solution Ca, Mg, and K increased and Al and manganese (Mn) concentrations decreased. Silicate released from basalt was able to lower the pHo (the pH at which the net charge of the variable charge minerals is zero), indicating a negative charge was being generated, which led to increase in the cation exchange capacity (CEC) of the Oxisol. The improvement in soil fertility because of application of the amendments had improved cocoa growth. Leaf K and P of the cocoa planted on the basalt-treated soils were within the sufficient range for cocoa growth. Rice husk compost applied at a rate of less than 20 t ha^?1 in this trial was not able to supply sufficient N to the cocoa. Basalt application at an appropriate rate effectively ameliorates acidic soil infertility, but it takes time to realize the positive effects of application as it slowly dissolves under field conditions.     

Leaching of metals from a spruce forest soil as influenced by experimental acidification

Acidified (H₂SO₄+HNO₃, 3:1) throughfall waters (pH 3.16 and 3.40 as volume weighted means or control (untreated throughfall water, pH 3.72) were applied for 3.5 yr by an automatic irrigation device to lysimeters containing podzolized spruce forest soils of 0–5, 0–15 and 0–35 cm soil depth. The total volume of the leachates was measured together with their pH and total content of DOC, Na, K, Ca, Mg, Fe, Mn, Al, Cu, Zn, Cd and Pb and the initial amounts of metals and H in the soil. The main part of H⁺ added with the throughfall waters was retained within the soil. Concentrations and fluxes of Mg, Ca, Mn, Zn and Cd in the soil were significantly increased by addition of acidified throughfall waters; K was less affected. As a consequence of lowered flux of DOC in the A horizon as acid input increased, Fe, Al, Cu, and Pb fluxes also decreased. The mobility of these metals in the A horizon was shown to be regulated mainly by the formation of watersoluble organic compounds rather than directly by pH variations. Compared to the control, the additional annual loss of Mg from the soil profile in the most acid treatment was c. 10% of the currently exchangeable amount.     

Soil Nutrient Status and Leaf Nutrient Norms in Oil Palm (Elaeis Guineensis Jacq.) Plantations Grown in the West Coastal Area of India

Oil palm (Elaeis guineensis Jacq.) is a heavy feeder of nutrients and requires balanced and adequate supply of nutrients for optimum growth and yield. Information regarding soil nutrient status and leaf nutrient concentration is very much required for proper fertilizer application. Therefore, a survey was conducted for assessment of soil nutrient status and leaf nutrient concentration in 64 oil palm plantations in the state of Goa lying in the west coastal region of India. Soil pH, electrical conductivity (EC), organic carbon (OC), available potassium (K) (ammonium acetate-extractable K) (NH₄OAc-K), available phosphorus (P) (Bray’s-P), exchangeable calcium (Ca) (Exch. Ca) and magnesium (Mg) (Exch. Mg), available sulphur (S) (calcium chloride-extractable S) (CaCl₂-S), and hot water soluble boron (B) (HWB) in surface (0–20 cm depth) soil layers ranged from 4.25 to 6.77, 0.05 to 1.06 dS m^–1, 5.07 to 48.4 g kg^–1, 58.1 to 1167 mg kg^–1, 1.80 to 415 mg kg^–1, 200 to 2997 mg kg^–1, 36.0 to 744 mg kg^–1, 3.00 to 87.7 mg kg^–1 and 0.09 to 2.10 mg kg^–1, respectively. Diagnosis and Recommendation Integrated System (DRIS) norms were established for different nutrient expressions and were used to compute DRIS indices. As per DRIS indices, the order of requirement of nutrients in the region was found to be P > Mg > K > nitrogen (N) > B. Optimum leaf nutrient ranges as per DRIS norms varied from 1.64 to 2.79%, 0.36 to 0.52%, 0.37 to 0.75%, 0.89 to 1.97%, 0.35 to 0.63%, 0.89 to 1.50%, 3.10 to 13.9 mg kg^?1, 7.50 to 32.2 mg kg^?1, 35.0 to 91.1 mg kg^?1, 206 to 948 mg kg^?1, and 895 to 2075 mg kg^?1 for N, P, K, Ca, Mg, S, B, copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) respectively. On the basis of DRIS-derived sufficiency ranges, 14, 5, 11, 6, 6, 6, 8, 2, 3, 6, and 16% of leaf samples had less than optimum concentrations of N, P, K, Ca, Mg, S, B, Cu, Zn, Mn, and Fe respectively. The optimum ranges developed can be used as a guide for routine diagnostic and advisory purpose for balanced utilization of fertilizers.     

控释肥对苹果根域环境的影响

采用苹果专用控释肥,设计不同试验处理,研究控释肥对果园土壤微生物,有机质,pH值和N、P、K、Ca、Mg、Cu、Fe、Zn、Mn等矿质元素含量的影响。结果表明,与普通复合肥相比,控释肥提高了果园土壤微生物量氮、微生物量碳和pH值,对有机质含量影响差异不明显;增加了土壤碱解氮、Fe和Zn含量,降低了土壤速效磷、交换性Ca、交换性Mg和Mn的含量,不同试验点速效钾和Cu的含量结果不一致;不同控释肥处理间大部分指标差异不明显。     

Pecan leaf analysis: I. Varietal,fertilizer, and seasonal effects

Abstract

Differences in elemental content of pecan [Carya illinoensis (Wang.) K. Koch] leaves among cultivars were found for N, P, K, Ca, Mg, Mn and Zn. Of the 7 elements studied, only leaf K indicated a date by cultivar interaction. Differences in leaf K among cultivars became greater as the season progressed. Increasing rate of application of N‐P‐K fertilizer increased leaf N, Ca, Mn, and Al, but had very little or erratic effect on leaf P, K, Fe, B, Cu, Zn, and Sr. There were very few consistent significant fertilizer rate by date interactions for the 13 elements tested. Seasonal trends for element leaf contents from mid‐May through October were generally downward for N, upward for Ca, Mn, Fe, B, Cu, Al, and Ba and changed very little for Mg, Zn, and Sr. Leaf P and K responses to sampling date varied with year. Large year to year variations in leaf trends over dates suggests difficulty in selecting a period for leaf sampling where little change in leaf levels consistently occurs.     

施肥结构对砂质潮土中微量营养元素空间变化的影响

本文通过长期定位施肥试验 ,分析了不同施肥结构对砂质潮土交换性钙、镁及有效硫、锌、锰、铜、铁等在 0～ 1 2 0cm土体中空间分布变化的影响 .结果表明 ,磷肥明显提高土壤交换性钙的含量 ,而有机肥与氮肥对土壤钙含量无明显影响 .但有机肥显著增加土壤交换性镁含量 ,各层镁含量与有机肥用量呈显著或极显著正相关 ,磷肥同样对土壤镁有提高作用 ,但氮肥无论是否与有机肥配施均降低了土壤各层交换性镁含量 .土壤 0～ 4 0cm有效锌、锰、铁均随有机肥增加而增加 ,并与有机肥用量呈极显著正相关 .而化肥无论是否与有机肥配施均降低土壤有效锌含量 ,但却增加了有效铁含量 .氮肥单施降低土壤有效锰含量 .在无有机肥情况下 ,施磷提高土壤有效铁含量 ,而在施有机肥条件下磷肥则降低耕层有效铁含量 .磷肥只在单施化肥时增加土壤有效锰含量     

Chemical soil properties and bromegrass hay composition as affected by 23 annual fall and spring applications of ammonium nitrate and urea

Abstract

The influence of nitrogen (N) fertilization on grass forage yield and quality as well as soil properties may vary with type of N fertilizer and time of application. The effects of 23 annual applications (from 1974 to 1996) of ammonium nitrate (AN) and urea (112 kg N ha^‐1) applied in early fall, late fall, early spring and late spring on chemical soil properties and composition of bromegrass hay were evaluated in a field experiment on a thin Black Chernozemic soil located near Crossfield, Alberta, Canada. The influence of N addition, fertilizer type and application time on the soil properties was most pronounced in the 0–5 cm layer and declined in deeper soil layers. Application of N increased extractable ammonium (NH₄)‐N, zinc (Zn), and iron (Fe) in the 0–5 cm layer; and sodium (Na), aluminum (Al), and manganese (Mn) in the 0–10 cm layer. But, N addition reduced extractable phosphoras (P) in the 0–30 cm; potassium (K) in the 0–60 cm; and pH, calcium (Ca), and magnesium (Mg) in the 0–5 cm soil layers. There was little effect of N fertilization on nitrate (NO₃)‐N in soil. Soil pH, and extractable Ca and Mg in the 0–5 cm layer and Zn in the surface 15‐cm soil depth were lower with AN compared to urea, whereas the opposite was true for Fe, Mn, and Cu in the 0–5 cm layer and Na and Al in the top 15‐cm soil depth. Most of the changes in chemical soil properties due to N fertilization were reflected in elemental concentration of bromegrass hay, except for the increase of P concentration in bromegrass with N fertilization. In bromegrass hay for example, N addition increased total N and Cu with both N fertilizers and Mn and Zn with AN, but it lowered K and Ca with both fertilizers. There was more N and less Na with AN than urea in bromegrass hay. The effect of application time on chemical soil properties and composition of bromegrass hay was much less pronounced than N addition and fertilizer type. In conclusion, both N fertilizers changed chemical soil properties and composition of bromegrass hay, but the effects of 23 annual applications on soil properties were confined to shallow soil layers only. The greater lowering of soil pH with AN than urea may have implications of increased liming costs with AN.     

Short range variability of soil chemistry in three acid soils in Ontario,Canada

Abstract

The objective of this study was to assess the efficacy of soil sampling and analysis methodologies used in Canada's Acid Rain National Early Warning System (ARNEWS). During July and August of 1992, twenty‐five soil pits were sampled and analyzed for available phosphorus (P); exchangeable potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), copper (Cu), manganese (Mn), zinc (Zn), aluminum (Al), sodium (Na), sulfate‐sulfur (SO4‐S), boron (B), and molybdenum (Mo); total nitrogen (N), P, K, Ca, Mg, Fe, Cu, Mn, Zn, Al, Na, sulfur (S), B, nickel (Ni), lead (Pb), and organic matter (O.M.); pH; and cation exchange capacity (C.E.C.) at three ARNEWS sites across Ontario. The soils were: i) a till‐derived Ferro‐Humic Podzol (Humic Haplorthod), ii) a Humo‐Ferric Podzol (Haplorthod) developed in coarse glaciofluvial sand, and iii) a Dystric Brunisol (Dystrochrept). The three sites were similar in chemical composition except for available P, exchangeable Ca, Mn, total Mn, O.M., and pH. Sample numbers calculated to achieve ±10% error with 95% confidence were much higher in mineral horizons than in forest‐floor horizons. Organic macro‐elements and pH were found to be the least variable parameters while micro‐elements were significantly more variable. Analyses are categorized into groups requiring similar numbers of samples. Other studies have found comparable levels of variability and their results are compared to coefficients of variation generated by the Ontario results. Variability within a pit was also observed and found to be less than that found across each 20‐ x 20‐m site but still very significant. Overall, the variability results from other studies appear to be applicable to Ontario acid soils for common analyses. Investigations observing micro‐elements, or which require high levels of accuracy, should incorporate pilot studies to ascertain the degree of variability for their location.     

An Investigation on Nutritional Problems of Hazelnut Grown on Acid Soils

Abstract

The purpose of the study was to determine the nutritional problems of hazelnut (Corylus avellana L.) grown on acid soils. For this purpose, soil and leaf samples were taken from 30 different hazelnut growing areas from Trabzon Region in Turkey. Some physical and chemical properties and some nutrient element contents of soil and leaf samples were determined. These determined values were compared with critical values, and the degree of sufficiency was evaluated. In general, organic matter, total nitrogen (N), available phosphorus (P), exchangeable potassium (K), and magnesium (Mg) contents of soil samples were sufficient. Calcium (Ca) deficiency was obtained in 93.4% of the soil, because of acid property of the soils. Available iron (Fe), copper (Cu), and manganese (Mn) contents of the soils were found to be sufficient. In 70% of the soils, Zn deficiency was found. Nitrogen, P, K, Ca, Mg, and Zn deficiencies of leaf samples were 20.0, 26.7, 6.7, 73.4, 50.0, and 66.7%, respectively. Iron, Cu, and Mn contents of leaf samples were found to be sufficient.     

Salinity induced effects on the nutrient status of soil,corn leaves and kernels

Abstract

The effect of salinity in inducing soil macro and micronutrient deficiencies that can decrease crop growth was evaluated in a corn (Zea mays L.) field located in east central Wyoming. In this study water soluble Na was found to be a better predictor of salinity than pH and other cations. Soil saturated paste extracts had electrical conductivities that were negatively correlated with soil total K, Cu, Fe, and Mn. Total N, NO₃‐N, PO₄‐P, Zn, pH, and water soluble Na, Ca, and Mg of the soil were positively correlated with EC. Significant positive relationships existed between soil EC and N, P, Mo, and Zn, and negative relationships with K, Cu, Fe, and Mn of corn leaves and kernels. Concentrations of nutrients in the kernels were positively correlated with corresponding nutrient concentrations in the leaves and with AB‐DTPA extractable soil nutrients. The analysis of variance of EC data indicated that soil samples possessing high salinity were higher in pH and contained significantly higher soluble Na, Ca and Mg, total N, N0₃‐N, PO₄‐P, and Zn and significantly lower Mn compared to samples having low salinity. The kernel weight per cob and plant height were significantly reduced as salinity increased.     

Seasonal dynamics of mineral nutrients and carbohydrates by walnut tree leaves

The dry weight accumulation per leaf as well as the concentration per gram of dry weight and the accumulation of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined in walnut tree leaves (Juglans regia L.) during a complete life cycle. Additionally, the dynamics of plant nutrient concentration in leaf petiole sap and carbohydrate accumulation in leaves were studied in relation to the main life cycle events of the walnut tree. Total N, P, K, Cu, and Zn concentrations decreased, whereas that of Ca, Mg, and Mn increased during the season. Iron concentration fluctuated around a mean value. Total N, P, K, Mg, and Cu concentrations detected in younger mature leaves were at the sufficient level, whereas Ca, Fe, Mn, and Zn concentrations were at higher levels as compared to those previously reported. All the detected nutrient accumulations increased abruptly during leaf ontogeny and leaf maturation until a maximum level was attained in the younger mature leaves. Similarly, sucrose, glucose, and fructose accumulation were observed at the same period. The rates of total N, P, Cu, and Zn accumulation were lower than the rates of the observed dry matter accumulation and nutrient concentration dilution. Potassium and Mn accumulation rates were almost equal, whereas those for Ca and Mg were higher as compared to the dry matter accumulation rate. The fast embryo growing phase resulted in a considerable decrease in dry weight, total N, P, K, Cu, Zn, and carbohydrate accumulation, and to a lesser degree in Ca, Mg, and Mn accumulation. Nutrient accumulation reduction in leaves by the influence of the growing fruits were estimated to be: total N 52%, K 48%, P 29.5%, Mg 16.3%, Ca 15%, Fe 51.2%, Cu 55.2%, Zn 37.3%, and Mn 5.4% of the maximum nutrient value of the younger mature leaves. Old leaves preserved nutrients before leaf fall as follows: total N 25.4%, P 45%, K 31%, Ca 74.8%, Mg 76.5%, Mn 89.2%, Fe and Zn 50%, and Cu 37%. Nutrient remobilization from the senescing old leaves before leaf fall were: total N 22.6%, P 25.5%, K 21%, Ca 10.2%, Mg 7%, Fe 3.2%, Mn 5.4%, Cu 8%, and Zn 13.3% of the maximum value in the younger mature leaves. In early spring, the absorption rates of N, P, and Ca were low while those of Mg, Fe, Mn, Cu, and Zn were high. During the fast growing pollen phase, the N, P, Fe, Mn, Cu, and Zn concentrations were reduced. Calcium concentration is supposed to be more affected by the rate of transpiration rather than during the growing of embryo. Calcium and Mg concentrations in the sap were negatively correlated. The detected K concentration level in the sap was as high as 33 to 50 times that of soluble N, 12 to 21 times to that of P, 5 times to that of Ca, and 10 to 20 times to that of Mg. The first maximum of starch accumulation in mature leaves was observed during the slow growing embryo phase and a second one after fruit ripening. Old senescing leaves showed an extensive carbohydrate depletion before leaf fall.     

Effect of presubmergence and green manuring (Sesbania aculeata) on nutrition and yield of wetland rice (Oryza sativa L.) on a sodic soil

Summary A field experiment was conducted to evaluate the effect of 0, 1 and 2 weeks' submergence prior to the transplantation of rice (presubmergence), with and without Sesbania aculeata green manure, on the yield and nutrition of rice in a highly sodic soil [pH 10.3, exchangeable sodium percentage (ESP) 86.4]. Green manuring significantly enhanced the yield of rice and contributed 112 kg N/ha. One week's presubmergence with incorporated green manure improved the yield of rice significantly over that obtained with no previous flooding, giving a yield on a par with that obtained with 2 weeks' submergence. The beneficial effect of presubmergence without green manure on rice yield was of lesser magnitude and was significant only when it was continued for 2 weeks. Cultivation of rice under submerged conditions improved the sodic soil, and green manuring enhanced the process of reclamation by further decreasing the pH value and the exchangeable Na of soil. Green manuring considerably improved organic C, available N, P, and K status of the soil and enhanced the uptake of N, P, Ca, Mg, S, Fe, Mn, and Zn by the crop. Effects of submergence and green manuring on the availability of Fe, Mn, Zn, and P in soil and their role in the nutrition of rice are discussed.     

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%.