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1.
The potential of Nostoc 9v for improving the nitrogen (N)2–fixing capacity and nutrient status of semi‐arid soils from Tanzania, Zimbabwe, and South Africa was studied in a laboratory experiment. Nostoc 9v was inoculated on nonsterilized and sterilized soils. Inoculum rates were 2.5 mg dry biomass g?1 soil and 5 mg dry biomass g?1 soil. The soils were incubated for 3 months at 27 °C under 22 W m2 illumination with a photoperiod of 16 h light and 8 h dark. The moisture was maintained at 60% of field capacity. In all soils, Nostoc 9v proliferated and colonized the soil surfaces very quickly and was tolerant to acidity and low nutrient availability. Cyanobacteria promoted soil N2 fixation and had a pronounced effect on total soil organic carbon (SOC), which increased by 30–100%. Total N also increased, but the enrichment was, in most soils, comparatively lower than for carbon (C). Nitrate and ammonium concentrations, in contrast, decreased in all the soils studied. Increases in the concentration of available macronutrients were produced in most soils and treatments, ranging from 3 to 20 mg phosphorus (P) kg?1 soil, from 5 to 58 mg potassium (K) kg?1 soil, from 4 to 285 mg calcium (Ca) kg?1, and from 12 to 90 mg magnesium (Mg) kg?1 soil. Positive effects on the levels of available manganese (Mn) and zinc (Zn) were also observed.  相似文献   

2.
Understanding the role of organic acids on phosphorus (P) sorption capacity of soils is very important for its economic and friendly management. Combining P application with low-molecular weight organic acids could result in its higher plant availability for prolonged time. Therefore, citric and oxalic acid (at the rate of 1.0 mM kg?1 soil) were evaluated for their effect on P sorption capacity and its plant availability in two different textured calcareous soils. Organic acids decreased P sorption capacity and organic carbon partition coefficient (Koc) whereas increased Gibbs free energy (ΔG) of P. Organic-acid-treated soils required lesser quantity of P fertilizer to produce soil solution P concentration optimum for plant growth (external P requirement [EPR0.2]), that is, 0.2 mg L?1. Citric acid was efficient than oxalic acid in the above effects. P sorption parameters of Freundlich model were negatively correlated with lime potential and ΔG whereas had positive correlation (P < 0.05) with EPR0.2 and Koc. Incubation with oxalic acid increased available P in loamy sand and loam soil by 20% and 30%, respectively. Thus, organic acids could help reduce application rate of P fertilizer through lowering its adsorption in highly P-fixing soils without compromise on yield.  相似文献   

3.
We analyzed in soils with contrasting cultivation histories the depletion of P following sequential extractions with soil testing solutions. Soil samples were collected in three experiments in eastern Canada (L’Acadie, Lévis, and Normandin) and P was sequentially extracted 16 times, once daily, using Mehlich-3 (M3) or Olsen (Ol) solution. The cumulative amount of P extracted was 252 mg PM3 kg?1 and 77 mg kg?1 POl for L’Acadie, 212 mg PM3 kg?1 and 66 mg POl kg?1 for Lévis, and 424 mg PM3 kg?1 and 83 mg POl kg?1 for Normandin. The depletion of P was described by a logarithmic function (Y = a ln (N) + b) for PM3, and a power function (Y = αNβ) for POl. The inorganic P pool decreased in the three soils. The organic P pool did not decrease possibly because soil testing solutions did not directly extract P from this pool. This study demonstrated that laboratory soil testing analysis using M3 or Ol solution principally target P from the inorganic pool, suggesting that P fertilizer recommendations to mineral soils relying on these methods do not account for the potential of the organic P pool to contribute to soil P availability.  相似文献   

4.
Abstract

Copper (Cu) is an important heavy metal to be considered in soil contamination, because high concentrations of copper in soil produce toxic effects and may accumulate in plant tissues. In Australia's oldest sewage irrigation farm, located in Werribee, Victoria, soil in the land filtration area is contaminated by Cu. However, Cu content in herbage tissues is in the normal range and has been trending downward since 1979. Therefore, studies on the sorption capacity and sequential extraction of Cu in soil at the Werribee Farm is of significance, not only for better understanding the mechanism of transport, chemical processes, and plant uptake of Cu, but also in providing information for the practical management of sewage farm soils. Methods of combining sorption isotherms with sequential extraction procedures were adopted, and the results showed that the soil in the land filtration area at Werribee Farm has a high sorption capacity for Cu, and distribution coefficients, Kf of Cu, were 629 L kg?1 in surface soils (0–20 cm) and 335 L kg?1 in subsurface soils (20–40 cm). The sequential extraction fractions demonstrate that exchangeable and carbonate fractions are very low, only comprising 3.49 to 5.49% of total copper. The other fractions are also discussed. This characteristic of Cu in soil is related to the low concentration of Cu in plant tissues.  相似文献   

5.
The physic nut tree (Jatropha curcas) is an oilseed species with potential for biodiesel production. We evaluated the effect of soil acidity indices on nutrient uptake for optimal growth in physic nut plants grown on acidic soils under greenhouse conditions. Two soils were used in the experiment. Maximum growth was obtained with the application of 1.05 g lime kg-1 for both soils. Maximum growth of the physic nut plants occurred under the following conditions: pH of water = 6.1, calcium (Ca2+) = 17.0 mmolc kg?1, magnesium (Mg2+) = 5.7 mmolc kg?1, acidity saturation = 10.3%, base saturation = 52.3%, Ca saturation = 36.0%, Mg saturation = 12.0% and potassium (K) saturation = 3.8%. Furthermore, the nitrogen (N) requirement of physic nut trees was shown to be high, and to a lesser degree, Ca and Mg requirements were also high, suggesting that liming is very important in crop cultivation of this species.  相似文献   

6.
Abstract

Nutrient sorption studies were carried out as a part of a mega project on “Yield maximization in cassava (Manihot esculenta Crantz) through systematic approach in fertilizer use” to find out the sorption characteristics of major, secondary, and micronutrients [i.e., phosphorus (P), potassium (K), sulfur (S), copper (Cu), zinc (Zn), manganese (Mn), and boron (B)] in a typic kandiustult of Kerala, India. The sorption curve fitted by using this study along with the results of preliminary soil analysis and critical level of these nutrients were used to optimize the nutritional status of this soil. Sorption study revealed that P, K, S, and B were limiting and others were sufficient for this soil. The quantities of the limiting nutrients required to optimize the soil nutritional status were estimated from the sorption curve as P, K, S, and B at 136 µg mL?1, 0.338 meq 100 mL?1, 20 µg mL?1, and 6.025 µg mL?1, respectively.  相似文献   

7.
An estimated 97 percent of the soils in Laos are characterized by low phosphorus (P). This characteristic, together with high acidity, constrains food crop production. The P status, sorption, and associated properties were evaluated for fifteen important agricultural soils from the uplands. Soil pH values ranged from 4.5 to 5.9. Soil organic carbon (C) varied from 7.0 to 22.9 g kg?1. Soil clay varied from 179 to 709 g kg?1. The cation exchange capacity (CEC) also varied from 4.30 to 32.1 cmolc kg?1. Extractable P levels of thirteen of the fifteen soils were P deficient with medium to very high P sorption, indicating substantial fertilizer P requirements. Dithionite and oxalate aluminum and iron predicted P sorbed at 0.2 mg P L?1. The extractable P increase per unit added P, P buffer coefficient (PBC), was low, also indicating high P sorption. Field studies are needed to confirm predictions of P requirements.  相似文献   

8.
The objective of this study was to investigate sorption, desorption, and immobilization of Pb in the clay and calcareous loamy sand soils treated with inorganic ligands (NO3?, Cl? and H2PO4?). Pb sorption was also determined in the presence of oxalate and citrate. The maximum Pb sorption capacities (q) ranged from 42.2 to 47.1 mmol kg?1 for the clay soil, and from 45.2 to 47.0 mmol kg?1 for loamy sand soil. It was observed that the binding energy constant (k) for Pb sorbed onto loamy sand soil (528–1061) is higher than that for clay soil (24.38–55.29). The loamy sand soil-sorbed greater quantities of Pb compared to the clay soil when initial pH was ≥ 3. However, it had lower sorption capacity at the lowest initial pH of 2. Additionally, the greatest Pb sorption and immobilization occurred in the soil treated with H2PO4. In the clay soil, the sorption of Pb was depressed at 0.1 mol kg?1 of Cl?, as compared with other ligands. Concerning organic acids, citrate ligand showed the highest decrease in Pb sorption. It could be concluded that the nature of Pb sorption can depend on the type and quantity of ligands present, as well as the soil type.  相似文献   

9.
Accurate estimation of the available potassium (K+) supplied by calcareous soils in arid and semi‐arid regions is becoming more important. Exchangeable K+, determined by ammonium acetate (NH4OAc), might not be the best predictor of the soil K+ available to crops in soils containing micaceous minerals. The effectiveness of different extraction methods for the prediction of K‐supplying capacities and quantity–intensity relationships was studied in 10 calcareous soils in western Iran. Total K+ uptake by wheat grown in the greenhouse was used to measure plant‐available soil K+. The following methods extracted increasingly higher average amounts of soil K+: 0.025 M H2SO4 (45 mg K+ kg?1), 1 M NaCl (92 mg K+ kg?1), 0.01 M CaCl2 (104 mg K+ kg?1), 0.1 M BaCl2 (126 mg K+ kg?1), and 1 M NH4OAc (312 mg K+ kg?1). Potassium extracted by 0.01 M CaCl2, 1 M NaCl, 0.1 M BaCl2, and 0.025 M H2SO4 showed higher correlation with K+ uptake by the crop (P < 0.01) than did NH4OAc (P < 0.05), which is used to extract K+ in the soils of the studied area. There were significant correlations among exchangeable K+ adsorbed on the planar surfaces of soils (labile K+) and K+ plant uptake and K+ extracted by all extractants. It would appear that both 0.01 M CaCl2 and 1 M NaCl extractants and labile K+ may provide the most useful prediction of K+ uptake by plants in these calcareous soils containing micaceous minerals.  相似文献   

10.
Abstract

In a greenhouse study, a significant increase in sunflower (Helianthus annuus L., cv. Hysun 33) dry matter yield was observed with boron (B) application to a B-deficient (hot water-extractable, 0.23 mg B kg?1) calcareous soil of Missa series (Typic Ustochrept). Six rates of B, ranging from 0 to 8 mg B kg?1 soil, were applied as H3BO3 along with adequate basal fertilization of nitrogen (N), phosphorus (P), potassium (K), and zinc (Zn). Four plants of sunflower were grown in each pot; two were harvested after 4 weeks of germination and the other two after 8 weeks. Maximum crop biomass was produced with 1.0 mg B kg ?1, and application of ≥2.0 mg B kg?1 proved toxic, resulting in drastic yield suppressions. Critical B concentration range for deficiency diagnosis in 4‐week‐old sunflower whole shoots appears to be 46–63 mg B kg?1. However, critical concentration in 8‐week‐old plants was much less (i.e., 36 mg B kg?l), presumably due to a dilution effect. As plant's internal B requirement can vary, in fact manifold, depending on the species, plant part, and plant age, only a relevant criterion can help in diagnosing the deficiency effectively.  相似文献   

11.
Irrigation with low-quality water may change soil hydraulic properties due to excessive electrical conductivity (ECw) and sodium adsorption ratio (SARw). Field experiments were conducted to determine the effects of water quality (ECw of 0.5–20 dS m?1 and SARw of 0.5–40 mol0.5 l?0.5) on the hydraulic properties of a sandy clay loam soil (containing ～421 g gravel kg?1 soil) at applied tensions of 0–0.2 m. The mean unsaturated hydraulic conductivity [K(ψ)], sorptive number (α) and sorptivity coefficient (S) varied with change in ECw and SARw as quadratic or power equations, whereas macroscopic capillary length, λ, varied as quadratic or logarithmic equations. The maximum value of K(ψ) was obtained with a ECw/SARw of 10 dS m?1/20 mol0.5 l?0.5 at tensions of 0.2 and 0.15 m, and with 10 dS m?1/10 mol0.5 l?0.5 at other tensions. Changes in K(ψ) due to the application of ECw and SARw decreased as applied tension increased. Analysis indicated that 13.7 and 86.3% of water flow corresponded to soil pore diameters <1.5 and >1.5 μm, respectively, confirming that macropores are dominant in the studied soil. The findings indicated that use of saline waters with an EC of <10 dS m?1 can improve soil hydraulic properties in such soils. Irrigation waters with SARw < 20 mol0.5 l?0.5 may not adversely affect hydraulic attributes at early time; although higher SARw may negatively affect them.  相似文献   

12.
The effects of zeolite application (0, 4, 8 and16 g kg?1) and saline water (0.5, 1.5, 3.0 and 5.0 dS m?1) on saturated hydraulic conductivity (K s) and sorptivity (S) in different soils were evaluated under laboratory conditions. Results showed that K s was increased at salinity levels of 0.5‐1.5 dS m?1 in clay loam and loam with 8 and 4 g zeolite kg?1 soil, respectively, and at salinity levels of 3.0–5.0 dS m?1 with 16 g zeolite kg?1 soil. K s was decreased by using low and high salinity levels in sandy loam with application of 8 and 16 g zeolite kg?1, respectively. In clay loam, salinity levels of 0.5–3.0 dS m?1 with application of 16 g kg?1 zeolite and 5.0 dS m?1 with application of 8 g zeolite kg?1 soil resulted in the lowest values of S. In loam, all salinity levels with application of 16 g zeolite kg?1 soil increased S compared with other zeolite application rates. In sandy loam, only a salinity level of 0.5 dS m?1 with application of 4 g zeolite kg?1 soil increased S. Other zeolite applications decreased S, whereas increasing the zeolite application to 16 g kg?1 soil resulted in the lowest value of S.  相似文献   

13.
To study the influence of potassium (K) fertilizer rate on soil test K values, crop yield, and K-leaching in sandy soils, four long-term fertilizer experiments (0–60–120–180 kg K ha?1 a?1) were initiated in 1988 in northern Germany on farmers fields. Clay content of the plow layer was about 4%, and organic matter between 2% and 5%. Plant available soil K was estimated with the double lactate (DL) method. Small grain cereals (rye and barley) did not respond to K fertilization in the 7-year period even though the soil test value of the K-0 plots decreased from ca. 90 to ca. 30 mg KDL kg?1 within 3 years. This value remained almost constant thereafter. Crop removal (including straw) of 75 kg K ha?1 a?1 was therefore apparently supplied from nonexchangeable K fractions. Compared to the optimum, no K application reduced the yield of potato by up to 21%, and that of white sugar yield up to 10%. Maximum potato yield was obtained by annually applying 60 kg K ha?1 which resulted in a test value of 60 mg KDL kg?1 soil. Maximum potato yield was also obtained at 40 mg KDL kg?1 soil, however, with a single application of 200 kg K ha?1. Similar results were obtained with sugar beet. This indicates that for maximum yield, even for K demanding crops, it is not necessary to maintain KDL values above 40 mg K kg?1 soil throughout the entire crop rotation. Soil test values increased roughly proportional to the K fertilizer level. About 120 kg fertilizer K ha?1 a?1, markedly more than crop K removal, was required to maintain the initial KDL of 90 mg kg?1. The K concentration of the soil solution in the top soil measured after harvest was increased exponentially by K fertilizer level and so was K leaching from the plow layer into the rooted subsoil. The leached quantity increased from 22 kg K ha?1 a?1 in the plot without K application to 42.79 and 133 kg Kha?1 a?1 in plots supplied with 60, 120 and 180 kg K ha?1 a?1 respectively. Soil test values around 100 mg KDL kg?1 on sandy soils, as often found in the plow layer of farmers fields, lead to K leaching below the root zone that may exceed the critical K concentration of 12 mg K T?1 for drinking water.  相似文献   

14.
Low selenium (Se) dietary intake has encouraged the development of fortification strategies such as SeO42- application to arable land. Selenate is highly mobile in soil systems, but it is not known whether fast abiotic retention could reduce Se loss from topsoil after SeO42- fertilisation. This work explicitly aims at fast abiotic SeO42- sorption in three soils exposed to 20–1250 µg L?1 Se in a 24-h batch experiment. This study demonstrated the susceptibility of Se sorption data to distortion when inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) measurements suffered from non-spectral interferences induced by concomitant elements in an aqueous soil-derived matrix. The distribution coefficient (Kd), not exceeding 2 L kg?1 at any Se level, was shown to be a useful indicator for the extent of ion competition for sorption sites depending on the SeO42- concentration employed. Sorption experiments conducted in the presence or absence of nitrate (10 mM), sulphate (0.52 mM) and phosphate (0.21 mM) allowed three phenomena explaining different SeO42- retention behaviours found even between similar Cambisols to be proposed. Finally, we showed that the co-application of sulphate or phosphate with SeO42- might decrease Se sorption from 150–170 µg kg?1 to a net release from native Se pool.

Abbreviations: 1st IP: first ionisation potential; RSD: relative standard deviation  相似文献   


15.
The effects of vermicompost (VC) (0% and 1% w/w) on treated calcareous clay soil with 0 and 50 mg phosphorus (P) kg?1 as calcium phosphate [Ca(H2PO4)2.H2O] was investigated. The soil samples were incubated for 7, 30, 60, 120, and 150 d at 25 ± 1°C and Olsen-P was measured after each incubation time. Results showed that Olsen-P increased 36% and 38% after VC addition in treated soil with 0 and 50 mg P kg?1, respectively. Recovery of Olsen-P in treated soils with VC, combined fertilizer VC + P, and fertilizer P was 42%, 42%, and 17%, respectively. The rate coefficient in treated soils with fertilizer, VC, and combined fertilizer VC + P was 0.033, 0.026, and 0.023 mg kg?1 d?1/2, respectively. It seems that the process that leads to the decrease in available P in amended soils, is controlled by P diffusion into sorption sites in micropores of aggregates.  相似文献   

16.
Abstract

Effective soil diagnostic criteria for exchangeable potassium (Ex-K) combined with inorganic potassium (K) application rates were developed to lower K input in forage corn (Zea mays L.) production using experimental fields with different application rates and histories of cattle manure compost. Two corn varieties, ‘Cecilia’ as a low K uptake variety and ‘Yumechikara’ as a high K uptake variety, were selected from among 20 varieties and tested to make diagnostic criteria for K fertilization applicable to varieties with different K uptakes. The K uptakes increased from 96 to 303 kg K ha?1 for ‘Cecilia’ and from 123 to 411 kg K ha?1 for ‘Yumechikara’ with increasing Ex-K content on a dry soil basis from 0.11 to 0.92 g kg?1 with no inorganic K fertilizer application. The K uptake by corn for achieving the target dry matter yield of 18 Mg ha?1 was estimated to be approximately 200 kg K ha?1 in common between the two varieties. Yields of both varieties achieved the target yield at an Ex-K content of approximately 0.30 g kg?1 with no K fertilization, although ‘Yumechikara’ reached the target yield at a lower Ex-K content. At the low Ex-K content of 0.1 g kg?1, inorganic K fertilizer application at 83 kg K ha?1 was needed to gain the target yield, and apparent K recovery rate for K fertilizer was calculated to be 70% for both varieties. The K uptakes for gaining the target yield by the K fertilization were lower than that by soil K supply. Based on these results, diagnostic criteria of Ex-K and inorganic K application rates were set up as follows: at an Ex-K content of < 0.15 g kg?1, inorganic K fertilizer is applied at 83 kg K ha?1 (100 kg ha?1 as potassium oxide (K2O) equivalent); at an Ex-K content of 0.15–0.30 g kg?1, the application rate is reduced to 33 kg K ha?1 (40 kg K2O ha?1); at an Ex-K content of ≥ 0.30 g kg?1, inorganic K fertilizer is not applied because of sufficient K in the soil. Additionally, we propose that cattle manure compost be used to supplement soil K fertility.  相似文献   

17.
Non-exchangeable potassium (Knex) contributes to soil K availability and several extractants are used to access its contribution. This study evaluated sodium tetraphenylboron (NaBPh4) as a soil test of K availability in 20 soils from Northern Greece. Winter wheat (Triticum aestivum L. var. ‘Yecora’) was sown in a greenhouse pot experiment and five cropping cycles were carried out until K-depletion. Soils were analyzed with NH4OAc and NaBPh4 (1 and 5 min incubation periods). Critical levels of K ranged between 130–140 and 330–340 mg K kg?1 of soil for NH4OAc and NaBPh4 (1 min incubation period), respectively, and between 32 and 35 g K kg?1 of wheat dry matter. NaBPh4-K (1 min) related better with K concentration and uptake compared to NH4OAc for each cropping cycle (r2 = 0.45–0.83 and 0.44–0.89) and for all soils (r2 = 0.58 and 0.51). Similar results obtained in soils low in exchangeable K (r2 = 0.41 and 0.39). Correlation between NH4Oac- and NaBPh4-extractable K was weaker among soils below the critical level (r = 0.70) compared to those above (r = 0.93). Inclusion of illitic K and cation exchange capacity in a multiple linear regression between NH4OAc- and NaBPh4-extractable K showed that they significantly contributed to NaBPh4-extractable K.  相似文献   

18.
Boron (B) is an essential microelement, which is necessary for reproductive organs including pollen tube formation in wheat (Triticum aestivum L.), and flowering and boll formation in cotton (Gossypium hirsutum L.) The study was associated with wheat-cotton rotation in 80 farm fields, belonging to different soil series, in four districts of cotton belt of Punjab, Pakistan to assess concentrations of extractable B in soils [0.05 M hydrochloric acid (HCl) extractable B], and added fertilizer B and their relationship to some soil physico-chemical properties [pH, organic matter (OM), calcium carbonate (CaCO3) and clay content], yields and total B concentrations in wheat and cotton plants. All soils had alkaline pH (7.45 to 8.55), high CaCO3 content (2.14 to 8.65%), less than 1.0% OM (0.33 to 0.99%), low plant available-P (Olsen P less than 8 mg kg?1 soil) and medium ammonium acetate extractable potassium (K) (< 200 mg K kg?1 soil). Of the 80 soil samples, 65 samples (81%) were low in available B (<0.45 mg B kg?1, ranging from 0.11 to 0.43 mg B kg?1) Of the corresponding 80 plant samples, leaves B concentrations were below critical levels (<10 mg B kg?1 for wheat; <30 mg B kg?1 for cotton) for all the tested samples for wheat and cotton. The regression analysis between plant total B concentrations and soil extractable B concentrations showed strong linear positive relationships for both wheat (R2 = 0.509***, significant at P <0.001) and cotton (R2 = 0.525***, significant at P <0.001). Further regression analysis between extractable soil B and wheat grain yield as well as between wheat leaves total B and wheat grain yield also depicted strong linear relationships (R2 = 0.76 and 0.42, respectively). Boron fertilizer demonstration plots laid out at farmers’ fields low in extractable B, in each district not only enhanced grain yields of wheat crop but also contributed a significant increase towards seed cotton yield of succeeding cotton crop through residual B effect. In conclusion, the findings suggest that many soils in the cotton belt of Punjab may be low in extractable B for wheat and cotton, especially when these crops are grown on low OM soils with high CaCO3 content.  相似文献   

19.
Abstract

This study was conducted to investigate the effect of time and rate of phosphorus (P) addition on phosphorus availability and phosphorus buffer coefficient in some calcareous soils. Phosphorus was added to the samples at rates of 0, 50, 100, 200, 400, 600 and 800 mg P kg?1 soil. The samples were incubated for 0.041, 1, 7, 14, 21, 30, 60 and 90 days at constant temperature and moisture. Extractable phosphorus was determined after the incubation. The results showed a sharp decrease in available P within 1 h after P addition. There was a linear relation between added P and extractable P in all soils. The buffer coefficients of soils were estimated by Olsen P for above incubation periods. Generally the buffer coefficient decreased with increasing time of incubation. The results indicated that inputs of between 23 – 59 mg kg?1 are required to raise Olsen P by 10 mg kg?1 in these calcareous soils, which assuming 2500 t soil ha?1, gives a required input of 58 – 148 kg P ha?1.  相似文献   

20.
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.  相似文献   

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