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1.
A major constraint to the renovation of forage legume‐based pastures on acidic soils of the Appalachian hill‐lands is thought to be the absence of effective rhizobia. A growth chamber experiment was done with aluminum (Al) toxic, low pH (≥ 4.2) soils from four series (Berks, Lily, Tate, and Westmoreland) that were planted with alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), white clover (Trifolium repens L.), or birdsfoot trefoil (Lotus corniculatus L.). These soils, without lime addition, were previously shown not to contain effective, naturalized populations of rhizobia for these plant species. However, a non‐toxic, pH 6.8, Watauga soil was shown to have such rhizobia but only for alfalfa. In the present study, these five soils were reexamined after liming to pH ≥ 5.5 for effective, naturalized populations of rhizobia and the efficacy of soil inoculation with commercially available rhizobia. In addition to effective, naturalized R. meliloti for alfalfa in the Watauga soil, similar populations of R. trifolii for red clover, and R. lotus for birdsfoot trefoil, were now found. Such rhizobia were also found for alfalfa in the Lily soil and for red clover in the Lily and Tate soil. Thus, liming allowed the expression of effectiveness of natural rhizobia that otherwise would not have been detected in soil pot experiments without lime. Inoculation of the toxic soils after lime addition with commercial rhizobia was effective in about half of the soil‐plant combinations that did not contain populations of effective, naturalized rhizobia. Asymbiotic shoot growth of all the plant species was significantly (P ≤ 0.05) correlated with soil pH over a range of 5.5–6.6. These results indicate that, in the absence of effective, naturalized populations of rhizobia, improvement of rhizobial inocula could increase forage production by ～34% for some species on some of the toxic soils, even after the pH of the soils is increased to ≥ 5.5.  相似文献   

2.
Kura clover (Trifolium ambiguum M.B.) is a persistent perennial forage legume that produces high-quality herbage for grazing, but its response to potassium (K), an essential plant nutrient, is unknown. Our objective was to determine the effect of four dipotassium oxide (K2O) rates on forage yields and stands of Kura clover compared to birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.). There was a significant linear response in Kura clover and alfalfa forage yields to K2O fertilization each year. Averaged over 4 years, Kura clover forage yield increased by 0.024 Mg ha–1 per kg of K2O applied, and the yield response was similar for alfalfa. Birdsfoot trefoil forage yield response to K2O fertilization was less than those of alfalfa and Kura clover. In the first 2 years after seeding, Kura clover forage yields were consistently less than for alfalfa at all rates of K2O fertilizer, but in subsequent years Kura clover yields were similar to or exceeded those of alfalfa. Final groundcover values, an estimate of stand density, of unfertilized (0 K2O rate) Kura clover, birdsfoot trefoil, and alfalfa were 86, 35, and 21%, respectively. Final groundcover of Kura clover and alfalfa was increased by K2O fertilization. We conclude that Kura clover has good persistence with low soil K fertility but stands and yields can be increased by fertilization.  相似文献   

3.
A growth chamber experiment was initiated with two field moist, marginal and acidic (pH 5.1–5.2) soils of the Lily series (Typic Hapludults) in order to determine the need for improved legume‐rhizobia symbioses for forage species of current, or potential, use in the renovation of Appalachian hill‐land pastures. One soil was from an abandoned pasture having broomsedge (Andropogon virginicus L.) as the predominant vegetation, whereas the other was from a minimally‐managed pasture dominated by orchardgrass (Dactylis glomerata L.). Treatments included inoculation (or no inoculation) and the addition of aluminum, nil, or lime to provide a range of soil acidities. Both soils contained effective populations of naturalized rhizobia for white clover (Trifolium repens L.) and red clover (Trifolium pratense L.), but low and/or ineffective naturalized populations of rhizobia for alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), bigflower vetch (Vicia grandiflora Scop.), and flatpea (Lathyrus sylvestris L.). Seed inoculation, by lime‐pelleting, was highly beneficial in establishing effective symbioses for all these latter species. The addition of low levels of aluminum or lime (1.5 and 2.0 cmol/kg soil, respectively) had little effect on any of the symbioses, with the exception of those for alfalfa. Thus, an improved legume rhizobia symbiosis would not seem to be a prerequisite for renovating pastures established on chemically similar ultisols with the forage legume species examined in this study, especially if the pasture has at least some history of management.  相似文献   

4.
Abstract

Wastes applied to agricultural land can contain significant concentrations of bioavailable molybdenum (Mo). Because Mo uptake by forage crops could lead to hypocuprosis in ruminants, more knowledge is needed about which crops are most efficient in accumulating Mo. At an old sewage sludge‐amended site, the concentrations of Mo, copper (Cu), and several other trace metals were measured in various grass species. Generally, the grasses grown on the sludge site contained higher Mo concentrations than the same species grown on a nearby control site. However, because Cu concentrations were also higher in the sludge‐grown grasses, Cu:Mo ratios in the grasses were frequently higher on the sludge site. In contrast, all legumes tested (alfalfa, birdsfoot trefoil, red clover, pea), as well as canola and beets, had lower Cu:Mo ratios when grown on the sludge site. Sulfur concentrations in the two crops analyzed for this element (canola and pea) were higher on the sludge site than the control. It is concluded that Mo, Cu, and sulfur (S) bioavailability remains elevated in the soil several decades after sewage sludge application.  相似文献   

5.
Abstract

Six legume species and several varieties within the species were grown in a greenhouse pot experiment using the Bt horizon of a Lily (Typic Hapludult) soil. Lime treatments were 0 and 2.2 g Ca(OH)2/kg soil. Liming increased the soil pH from 4.6 to 6.2. The species and varieties responded differentially to lime. Both shoot and root growth of legumes showed a significant species and lime interaction effect. Based on tolerance index groups for shoot growth, alfalfa varieties were classified as very sensitive, red clovers and white clovers as sensitive and Essex soybean and Carroll birdsfoot trefoil as tolerant to the acid soil. The remaining legumes were grouped as moderately tolerant to the acid soil. Liming increased shoot concentrations of Ca in all the legumes and reduced concentration of Mg, K, and Zn. Species and varieties within species differed significantly in concentrations of all mineral elements studied except Mg. Further significant differences in elemental composition were observed due to both lime and lime species interactions. In the limed soil, the Ca concentration of the shoots increased as the tolerance index decreased.  相似文献   

6.
Abstract

Birdsfoot trefoil (Lotus tenius), red clover (Trifolium pratense) and white clover (Trifolium repens) were evaluated as potential forage legumes on andic soils. A greenhouse study was used to evaluate the influence of soil pH on: (1) the establishment and growth of these forage legumes, (2) N and P quantity and concentration, and (3) Rhizobium lupini and Rhizobium trifolii survival.

Aluminum sulfate and finely‐ground calcium carbonate were used to adjust soil pH. Soil pH's were 4.8, 5.1, 5.6, 6.2, 6.4, 6.9, 7.0 and 7.4. Birdsfoot trefoil, red clover and white clover were grown in 15 cm pots in the greenhouse and harvested five times at approximately 20‐day intervals. Yield was measured and plant material was analyzed for total N and P. Populations of R. lupini and R. trifolii were monitored using the MPN technique.

Manipulation of pH in the Mission soil was found to have a significant effect on the growth of the three forage legumes, tissue N and P concentration and uptake, and on the survival of R. lupini and R. trifolii in the soil. In general, tested parameters increased with increasing soil pH. Greatest forage yield occurred in the 6.9–7.0 pH range. The andic nature of the Mission soil requires a pH adjustment above pH 6.2 for acceptable establishment and yields of the three forage legumes studied. This is in sharp contrast to non‐andic northern Idaho soils where forage legume yields are usually not adversely affectea above pH 5.5. All three legumes appeared to have good potential ana should be evaluated under field conditions.  相似文献   

7.
Grain sorghum [Sorghum bicolor (L.)], grown on the often infertile claypan soils of the eastern Great Plains, requires attention to soil fertility. Experimental objectives were to determine the effects of phosphorus (P) and potassium (K) fertility levels, N application, and legume residual on grain sorghum production and stalk rot. Following alfalfa and birdsfoot trefoil, first-year sorghum yield was 7 Mg ha?1 and not affected by N fertilizer. In subsequent years, yield increases due to N were less than 20%. Sorghum yield increased at low P and K rates, especially with nitrogen (N) fertilization and was greater following birdsfoot trefoil than following alfalfa. In 1995 when fertilized with N, lodging and stalk rot severity were increased by P and reduced by K. In 1996, stalk rot severity was reduced by K fertilization. Grain sorghum, grown after legume crops, required minimal levels of P and K, especially when N fertilizer was added.  相似文献   

8.
Response of alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), and red clover (Trifolium pratense L.) to aluminum was evaluated in a nutrient culture system under controlled conditions. In each of the species, varietal differences were also compared. In the absence of Al stress, varieties of alfalfa and Tensas red clover produced more dry weight than the other legumes. However, among the legumes tested, alfalfa was the most sensitive to Al. Aluminum reduced the uptake of many of essential nutrients. Overall, red clover cultivars experienced the least reduction in elemental uptake, whereas alfalfa cultivars experienced the greatest reduction in uptake of elements under Al stress. The efficiency ratio (ER) assisted in differentiating legumes entries into efficient and inefficient utilizers of absorbed nutrients. The ER is defined as milligrams of dry shoot weight produced per milligram of element in the shoot. The presence of Al in the growth medium reduced the ER for all elements. With a few exceptions, ER for various elements, gave positive correlations with shoot weight. The species and cultivars used in this study showed inter‐ and intraspecific differences in growth, uptake of nutrients and nutrient efficiency ratios in the presence or absence of Al stress.  相似文献   

9.
Crop response to fertilization and liming was investigated in field and pot trials on sandy loam Dystric Albeluvisols (pH 4.2–4.3). Treatments in the field trial were: 1, no fertilizer; 2, PK; 3, NK; 4, NP; 5, NPK; 6, lime; 7, lime+PK; 8, lime+NK; 9, lime+NP; 10, lime+NPK. In the pot trial, they were: 1, no fertilizer; 2, N; 3, P; 4, K; 5, NP; 6, NK; 7, PK; and 8, NPK applied to unlimed and limed soils. All treatments were in four replicates. Crops sensitive to soil acidity (winter wheat, fodder beet, spring barley and clover-timothy ley) and the less acid-sensitive winter rye, potatoes, oats and lupins and oats mixture were sown in the field trial. In the pot trial, the acid-sensitive spring barley and red clover, and the less acid-sensitive oats and lupin-oats served as the test crops. Combined application of fertilizers (NPK) increased yields of crops sensitive to soil acidity in plots receiving lime by 23%, and those of crops less sensitive to soil acidity by 18% in comparison to crops grown on unlimed soils. The results of pot experiments corroborated the field results. When N was applied alone, crop yields were always higher than those recorded for P or K treatments on both the unlimed and limed treatments. N application proved to be a prerequisite for high crop yields in the soils investigated. Thus, the efficiency of P and K fertilizers increased in the order NK<NP<NPK, with the effects being accentuated more in the limed than in the unlimed treatments. The results demonstrated the importance of multi-nutrient (NPK) fertilization in combination with liming for enhancement of high crop productivity in the unlimed soil investigated. N applied alone in combination with liming produced relatively good yields; hence, where resources are limited for the purchase of P and K fertilizers, applying N and lime can be a viable option in the short term.  相似文献   

10.
Three perennial legumes (alfalfa, red clover and birdsfoot trefoil) and four cool-season perennial grasses (orchardgrass, tall fescue, Italian ryegrass and red fescue) were grown in legume–grass combinations and in pure stands of individual species, at three locations in the West Balkan region (Novi Sad, Banja Luka and Pristina) in the period from 2012 to 2015. The study evaluated dry matter yield, legume–grass–weed proportion and forage quality. High annual forage yield of legume–grass mixtures can be obtained with proper selection of species and an appropriate legume–grass ratio. However, high and stable yield, particularly in the case of grasses, depends on the amount and schedule of precipitation as well as the cutting time. The mixtures and legume pure stands achieved better forage production both per cutting and on the annual basis and had better forage quality than grass pure stands.  相似文献   

11.
Abstract

Lime‐stabilized sludge (LSS) from dairy processing waste‐water treatment plants is a desirable product for land application. The material contains lime, which neutralizes soil acidity, and P, which is useful as a plant nutrient. The fineness of the lime and the solubility of P make LSS especially desirable in establishing forage legumes. This greenhouse study had two objectives: to determine a reasonable quantity of LSS for establishing forage legumes such as alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) and to prevent adverse effects on seedlings. Sludge was applied at 0, 2.5, 5.0, 7.5 g kg‐1 to an acid, low P soil in pots, and alfalfa and red clover seeds were sown. All treatments received 123 μg g‐1 potassium as KCl. A completely randomized design with four replications was used. Each species was handled as a separate study. Dry matter production was measured at one‐tenth bloom stage. Plant samples were analyzed for P, K, Ca, and Mg content. Soil samples taken at the end of the study were analyzed for pH, organic matter, Bray P, K, Ca, Mg, exchangeable Al, EC, and CEC. The higher quantities of LSS (7.5 g kg‐1 for alfalfa and 5.0 g kg‐1 for red clover) had negative effects on seedling germination and establishment. Lime‐stabilized sludge resulted in an increase in total nutrient uptake of Ca, Mg, K, and P up to 5.0 and 2.5 g kg‐1 in alfalfa and red clover, respectively. In both species significant dry matter yield increases were obtained with LSS up to 5.0 g kg‐1; however, 7.5 g kg‐1 caused a reduction in dry matter yield. Based on these results, applications of LSS at 5.0 for alfalfa and 2.5 g kg‐1 for red clover had positive effects in seedling establishment, nutrient uptake, and dry matter production. Lime‐stabilized sludge application resulted in significant increases in soil pH, available P, Ca, Mg, EC, and CEC; decreases were seen in neutralizable acidity and exchangeable Al levels in soil. This study indicates that LSS is appropriate for the acidic, low P soils of Southern Missouri for alfalfa and red clover establishment and production, if applied in appropriate quantities.  相似文献   

12.
Abstract

In seeking reasons for differences in sensitivity among vegetables to low soil pH and the roles of lime and fertilizers, an experiment was conducted in 1984 with 3 crops: snapbeans (Phaseolus vulgaris L.), tomatoes (Lycopersicon esculentum L.), and red beets (Beta vulgaris L.). The lime treatments, check, calcitic lime, and dolomitic lime, were applied in 1979 and resulted in soil pH levels of 5.5, 6.9 and 6.7, respectively, at the time of planting. Banded fertilizer treatments were randomized in each lime plot. These were: check, NP, N, NPK, NPCa, and NPMg for snapbeans while with tomatoes and beets, K was added to the N, NPCa and NPMg treatments. Leaf samples from each plot were analyzed for 11 elements.

Growth responses of the 3 crops were related to the plant sensitivity to acid soils. When grown on soil with pH 5.5, snapbean vine weights and pod yields were not affected, tomato yields tended to be lower, and red beet yields were substantially reduced. Leaf Mn levels increased with the greater sensitivity to acid soils. Both calcitic and dolomitic limes had little effect on snapbean yields, moderate effects on tomato yields, and more than doubled yields of red beets. Lime types affected primarily leaf Ca and Mg. The NPK fertilizer treatment increased yields of tomatoes and red beets but increased only vine weights of snapbeans. Leaf Mn was increased substantially in the NPK treatment. When gypsum or Epsom salts was added, yields were not affected.

The sensitivity of red beets and to a lesser extent tomatoes could not be explained on the basis of manganese toxicity or poor uptake of calcium or magnesium. The results did suggest that poor phosphorus uptake could be a primary cause.  相似文献   

13.
Abstract

The saturation extraction method for measuring available B in soil provided variable results and a narrower range thus making this test more difficult to interpret than tests with the boiling water method.

No close relationship between available soil B and either soil texture or soil pH level was found. The available B in soil ranged from 0.16 to 0.95 ppm with the highest level reflecting the recent use of B. The B level in the profiles of three typical sugarbeet‐bean soils ranged from none detectable in the subsoil to 0.54 ppm in the surface soil.

A survey of cropped versus uncropped soils showed that, on the average, cropped soil contained two‐thirds as much B as uncropped soil, suggesting that more extensive B deficiencies may occur in the future. Soil test levels for B in a calcareous soil decreased rapidly after B application. In this experiment soil B levels in excess of 1.5 ppm represented a potentially toxic condition for beans while any level above 2.0 ppm represented a definite toxicity. The bean plant B threshold level was in excess of 100 ppm. In the range of potential toxicity, bean yields and B soil tests were more closely related than were bean yields and B plant tests.  相似文献   

14.
Abstract

More uniformity in methods of deriving fertilizer P recommendations from crop response data should improve accuracy and precision of fertilization rates. Experimental data that relate crop yields to soil test levels and describe the effect of fertilizer P on soil test levels provide the basis for determining fertilization rates for specific crop‐soil situations. A modification of the Mitscherlich equation was used in derivation of a new equation for calculating fertilizer P requirements as a function soil test levels of P. The equation was applied to response data for 4 crops.

Response curves and fertilizer requirements as calculated for corn, soybeans, alfalfa, and clover‐grass indicated that soybeans yielded relatively more than the other three crops at low soil test levels of P. Corn and alfalfa required higher soil test levels to reach 95% maximum yield and required higher rates of fertilizer P when initial test levels were low.  相似文献   

15.
Abstract

The cost and difficulty of applying lime on hilly pastures or small forage fields makes it appropriate to devote attention to efficiency of lime utilization. This study evaluated effects of calcitic and dolomitic lime on yield and mineral composition of 11 forage species grown on soil with a low base status of 0.46 cmolc as Ca and 0.18 cmolc as Mg kg‐1. Both lime types increased dry matter production, but only Lolium multiflorum responded more positively to dolomitic lime. The low Mg level in the soil was not a major factor limiting yield. Increase in yield was mainly attributed to the increase in pH with the concurrent decrease in Al level and to an increased Ca availability to plants. The species ranked as follows according to the magnitude of yield increase due to calcitic liming: Trifolium fragiferum > Trifolium pratense > Vicia sativa > Vicia villosa > Trifolium repens > Lolium perenne > Lolium multiflorum > Festuca arundinaceae = Lolium (multiflorum x perenne x perenne) > Trifolium subterraneum > Dactylis glomerata. The most responsive, Trifolium fragiferum, did not grow without lime. The least responsive, Dactylis glomerata, showed a yield increase of 36%. A similar ranking was obtained when all species were evaluated for Al tolerance using a 48 hour root elongation bioassay. In both unlimed soil and soil limed with calcitic lime, Mg concentrations of all species were relatively low. Although they were generally not low enough to have an effect on yield, they barely met the Mg nutritional requirement of cattle. By adding dolomitic lime, Mg content increased in grasses an average of 3.7 fold and in legumes by 2.4 fold. Grasses were similar in Ca, Mg, and K concentrations within a soil treatment. Legumes showed a greater range with the two vetches having the lowest Ca and Mg concentrations and red clover the highest.  相似文献   

16.
An on-farm field experiment was conducted on an acidic soil to investigate the effects of combined use of lime and deficient nutrients on herbage yield of alfalfa (Medicago sativa L.). Omitting lime and limiting nutrients led to elevated concentrations of aluminium (Al), iron (Fe), and manganese (Mn) in alfalfa leaves and stems and caused severe reductions in herbage yield of alfalfa. Combined use of lime (2 t ha?1) and nutrients [phosphorus (P): 20 kg ha?1, sulfur (S): 20 kg ha?1, zinc (Zn): 4 kg ha?1, and boron (B): 2 kg ha?1] had the maximum increase in groundcover, root biomass, nodulation, leaf retention, leaf-to-stem ratio, herbage yield, crude protein, and nutrient composition of alfalfa. These beneficial effects were due to raised soil pH; improved calcium (Ca), P, S, Zn, and B nutrition; and reduced Al, Mn, and Fe toxicity. Aluminium and all the nutrients except copper (Cu) were more concentrated in alfalfa leaves than stems.

Aluminum concentration was about three times greater in the lower leaves than in upper leaves. Lower leaves also had much greater concentrations of Ca, Mg, K, S, Fe, Mn, Cu, and B compared with upper leaves. In contrast, P and Zn concentrations were greater in the upper leaves than in lower leaves. Results suggest that the combined use of lime and all the limiting nutrients may realize potential beneficial effects of alfalfa on acidic soils where more than one essential nutrient is deficient. This may increase growth potential, nitrogen contributions, and groundcover by alfalfa and reduce soil erosion and runoff.  相似文献   

17.
Abstract

A greenhouse study was conducted to evaluate the long‐term availability of radiocesium (Cs‐137) to various crops grown on contaminated soil that were limed to pH 6.8 (LIME) or were limed and Zn‐ and Mn‐EDTA chelates added (LIME + CHELATE). Crops were grown either continuously or followed a cropping sequence. Continuously grown clover and bahiagrass accumulated the most Cs‐137 with levels exceeding 2,000 pCi/g dry weight in bahiagrass. Uptake of Cs‐137 was depressed by both the LIME and LIME + CHELATE treatments. Uptake was usually greatest during the first three years but only in unlimed soil. Cesium‐137 is about 3 to 8 times higher in soybean beans than in wheat grain. Uptake of Cs‐137 by plants from contaminated soil can be expected to be high in acidic soils, especially in the absence of lime treatment.  相似文献   

18.
Mo contents of some crops and grassland plants of Schleswig-Holstein in relation to soil factors . The Mo content of about 170 plant samples of typical soils of Schleswig-Holstein were in the range of 0,2–11 ppm, increasing from grass to red clover, white clover and rape. By comparison with limiting values for adequate Mo supply (0,3 ppm Mo for red clover and probably also for the other three plants), a fairly good supply of the plants investigated can be deduced. The factors responsible for the varying Mo contents of plants are first of all the pH-value, furthermore the content of active iron and available phosphorus in the soil. The different contents of oxalat-soluble Mo had apparently no influence in this range of good supply. Whereas the correlation between one soil factor and plant Mo content was high only in some cases, coefficients of determination of up to 80% resulted from the use of several factors by multiple correlation.  相似文献   

19.
Polyphenol oxidases (PPOs) oxidize o-diphenols to o-quinones, which cause browning reactions in many wounded fruits, vegetables, and plants including the forage crop red clover (Trifolium pratense L.). Production of o-quinones in red clover inhibits postharvest proteolysis during the ensiling process. The cDNAs encoding three red clover PPOs were expressed individually in alfalfa (Medicago sativa L.), which lacks detectable endogenous foliar PPO activity and o-diphenols. Several physical and biochemical characteristics of the red clover PPOs in alfalfa extracts were determined. In transgenic alfalfa extracts, red clover PPOs exist in a latent state and are activated (10-40-fold increase in activity) by long incubations (>2 days) at ambient temperature or short incubations (<10 min) at > or =65 degrees C. PPO1 appears to be more stable at high temperatures than PPO2 or PPO3. During incubation at ambient temperature, the molecular masses of the PPO enzymes were reduced by approximately 20 kDa. The apparent pH optima of latent PPO1, PPO2, and PPO3 are 5.5, 6.9, and 5.1, respectively, and latent PPO1 is slightly activated (~5-fold) by low pH. Activation of the PPOs shifts the pH optima to approximately 7, and the activated PPOs retain substantial levels of activity as the pH increases above their optima. The latent and activated PPOs were surveyed for ability to oxidize various o-diphenols, and activation of the PPOs had little effect on substrate specificity. Activation increases the V max but not the affinity of the PPO enzymes for caffeic acid. Results indicate red clover PPOs undergo structural and kinetic changes during activation and provide new insights to their effects in postharvest physiology.  相似文献   

20.
In Indian agriculture, nitrogen (N) and phosphorus (P) fertilizers are predominantly used by the farmers, often ignoring secondary and micronutrients. Significance of boron (B) in nutrient management studies has been increasingly underlined under intensive cropping systems particularly in acid soils. In order to understand the distribution of soil native B in different fractions and their contribution to plant B uptake as influenced by nutrient management, soil samples collected after wheat (2009–2010) from a long-term experiment (LTE) continuing since 1972–1973 on Typic Paleustalf of Ranchi were subjected to sequential fractionation of soil B. Treatments included N alone, NP, NPK, 150% of recommended NPK, NPK + farmyard manure (FYM), NPK + lime, and an unfertilized-control. Five soil B fractions were determined along with hot CaCl2-extractable (available) B. Averaged across the treatments, the soil had low organic carbon (C), pH and cation exchange capacity (CEC), and high free sesquioxides. Total B content was 21.7 mg kg?1. Among different B fractions, residual B was the major contributor to total B and other fractions collectively shared 7% of total B only. Application of N alone depleted readily soluble, specifically adsorbed and organically bound B bringing the contents even below unfertilized-control. Conjoint use of lime or FYM with NPK increased significantly these fractions, whereas a decrease in oxide bound B was noticed under these treatments. Available B was positively correlated with these fractions indicating their significance in controlling B availability in the soil. The study revealed that use of lime or FYM helped modifying the distribution of soil B in different fractions by way of changing soil pH and organic C content, resulting in enrichment of plant available pool. A drastically low available B content in different treatments receiving fertilizers alone, however, suggested the necessity of B fertilization at prescribed rates for maintaining soil B fertility as also high crop yields.  相似文献   

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