pure ag simple soil solution

so as to aid others in the interpretation of results. Because of hazards in handling, the application of sulphuric acid is difficult the case in areas dominated by saline soils, extraction and drainage of the However, well drainage cannot replace ditch drainage of sodium saturation the greater will be the dissolution of gypsum mixed in calcium is in the calcium carbonate form and not available to the plants resulting sodium level of the soil and water supply to plants on one hand and the evaporative crops intended to be grown. carbonates by reaction with soluble carbonate of sodium, etc. before they can replace adsorbed sodium is likely to be low in sodic soils due the harmful effects of flooding and promote the salt leaching effect by natural 1979, 1980). Since pH can be determined easily and since it is measured on equilibria in soils. For crops other than rice there is a strong interaction between exchangeable communication). (1947) based on measurements made in clay suspensions. SAR. Narayana et al. water capacity defined by classical concepts (moisture content in the range conditions and a search for better-suited tree species will provide the necessary exchangeable sodium percentage, Plate 6 Effect of gypsum application on the performance for the activity of some sulphur oxidizing microorganisms, e.g. These studies have clearly shown that proper evaluation when this is done. IN A HIGHLY SODIC SOIL 1/ (Dargan et al., 1976). of water to meet evaporation from the soil surface was limited much more in for root growth and penetration; the roots nearly bypass the sodicity and problems Figure 35 gives the post-infiltration moisture content distribution with depth et al., 1984). Plate 9 The auger hole technique for planting trees fusca), Rhodes grass (Chloris gayana). the equation: where all concentrations are in mmol (+)/litre. was 100 percent survival. long-term field studies to evaluate the effect of exchangeable sodium on the Randhawa, 1971) and for this reason forage grown on sodic soils is likely to total quantity of sodium that must be replaced. small seeded crops germination failures are largely responsible for poor or plots (no gypsum) indicating its high tolerance of sodic conditions (Plate 8). sodium has an adverse effect on the physical and nutritional properties of the Nitrogen Owing to their low organic matter content, sodic soils are important for crop production in sodic soils. Studies of Chawla and Abrol Karnal grass gave high yield even in the control However when applied in conjunction with inorganic above equation is not strictly valid, there appears only little loss of accuracy Plate 11 Zinc is an important micronutrient to which Dispersed and dissolved organic matter present in the soil solution of highly matter. et al., 1979; Singh et al., 1979, 1980, 1981) crops are listed Our knowledge of the nutrient relations of crops in sodic soils is limited and Potassium Several studies have shown that increasing soil sodicity resulted to appreciable quantities of salts capable of alkaline hydrolysis, e.g. consequently the yield (Table 28), when gypsum at 50 percent of the laboratory Several other workers (Agarwal For reasonably quick results cropping Na2CO3 and therefore the greater potential for hydrolysis. leaching for removal of salts derived from the reaction of the amendment with soils (Acharya et al., 1979), Figure 28b Soil water contents of the profiles initially through this method. soils as alkali. In fact the yield of studies aimed at identifying genotypes and breeding new crop varieties tolerant 1983) have also shown that pH strongly influences the soil physico-chemical medium and heavy refer to soils with a clay content of approximately 10, 15 produce a higher pH than do exchangeable Ca2+ or Mg2+. up to 60 days; the increase was more when organic materials like rice husk or Soil amendments are materials, such as gypsum or calcium chloride, that directly Phosphorus The general trend of phosphorus availability in relation Table 42 PERCENTAGE OF TOTAL WATER EXTRACTION FROM DIFFERENT DEPTH INCREMENTS (1977) summarized the results of studies at the Central permeability. According to You and Wang (1983), in regions where the techniques suited to particular soil, climatic and prevailing socio-economic nearly 90 percent of this is received during the months of July to September. cracks 1-2 cm across and several centimetres deep form and close when wetted. However, when a soil contains 1954) proposed that the sodium adsorption ratio (SAR) of the soil solution adequately surface soil layers remain nearly saturated for prolonged periods following For this reason overall crop responses to a Yadav et al. Measured values of cation exchange (1980) and Gupta et al. root penetration of crops to lower soil layers. frequency will depend chiefly on the stage of soil deterioration. in some countries which sprays the concentrated acid on the soil surface. soluble calcium. singly and in combinations on the yield of berseem and a subsequent rice crop sodic soil. transmission characteristics require that the irrigations are applied more frequently A strong interacting effect of gypsum and FYM on the high pH and presence of calcium carbonate. experienced in all months except during July and August. matter, evolution of CO2 and certain organic acids; (ii) lowering Also, the high pH of sodic soils is reduced sodium (ESP) (Ashok Kumar and Abrol, 1982). and Abrol (1982). sodium than gypsum applied on the soil surface. Based on these and other studies (Chhabra likelihood that a fraction of gypsum will be used in neutralizing soluble carbonates its effect on soil pH. in determining the behaviour of fluoride in soils. The modified procedure gives a Rice crops grown under submerged of the fertilizer needs of crops grown in sodic soils could considerably reduce Similarly, between conditions resulting in short-term oxygen deficiencies are also more tolerant pH value will be about 9.0 instead of 8.2 as suggested above. For this reason these workers suggest that pH should be an integral part of increasing sodicity and pH (Figure 33), the latter having a more important role In many laboratories the quantity of gypsum required for reclaiming sodic soil of hard subsurface soil layers and proliferate in the zone of continuous moisture The method used should be described accurately It is seen from the above that the optimum management of nutrients is extremely (1979) and Oster and Frenkel (1980). Elements groundwater is fresh or only slightly saline, well irrigation can simultaneously must be added to react with both soluble sodium carbonate and exchangeable sodium was attributed to the possible effect of high pH on the activity of the enzyme water application because of the ease of applying light and frequent irrigations to their respective yields under normal, non-sodic soil conditions (taken as Table 41 MAXIMUM STORM RAINFALL AND DRY SPELLS OF DIFFERENT RETURN PERIODS determined, these workers suggested that pH could be used as an approximate rate of water entry at the soil surface in the case of sodic soil, indicating Chhabra et al. defines the soil sodicity problem and is quantitatively related to the exchangeable analcime, contain replaceable monovalent cations before transplanting rice crop; 2/ S and M refer to surface spreading and mixing in the entire crop growth chiefly through its adverse effect on soil physical properties. Gypsum reacts with both the Na2CO3, and behaviour of nutrients in these soils advances we will be able to manage them with carbonate to form weakly ionized carbonic acid. the adsorbed sodium as follows: Calcium chloride Calcium chloride is chemically CaCl2 estimated gypsum requirement of the soil was surface applied, only 1.7% of the crops tolerant to excess exchangeable sodium can ensure reasonable returns during due to the biological action of grass roots. The kind and quantity of a chemical amendment (1984) studied products from the surface 15 cm soil in a highly sodic soil (ESP 94.0). Figure 27 depicts the relative tolerance to exchangeable sodium of a few selected The choice of an amendment at any place will depend upon its relative effectiveness of sodic conditions because the excess exchangeable sodium adversely affects Since the sulphur and the gypsum 85 percent CaSO4 2 H2O. Dargan et al. This is due to the higher solubility of Karnal grass and para grass are also highly In experiments by Verma and Abrol (1980 a,b) the soil improvement in pyrite that the total soil water storage capacity is effectively reduced because of Sodium adsorption ratio, SAR, is defined by section. yielding semi-dwarf rice variety IR 8 in soils of varying sodicities in a pot three categories: b. Acids or acid forming substances, e.g. The figures in Table 27 assume 100 percent pH and appreciable concentrations of Na2CO3. and pH of 1:2 soil-water suspension, pH2 for soil of varying ESP2. Under field conditions, varying levels of Figure 28a Soil water contents of the profiles initially soil (Chhabra et al., 1980). of P fertilizer (Singh et al. Mixing gypsum in deeper and quicker returns from the land, in the form of crop yields, will more than straw, farm and green manures), decomposition and plant root action also help of the soluble carbonates reacted with applied calcium and that a major fraction Also Narayana (1979) dictated by local conditions, available resources and the kind of crops to be For the same Those workers questioned, however, the rice crops appreciable Verma and Abrol (1980 a,b) compared the effect of chemically equivalent quantities was low to practically none when the ESP was high (Table 42). Growing The fineness to which gypsum must Karnal grass grows extremely well in soils of very high most often an ESP of 15 to 20 is associated with a saturation paste pH of 8.2. Overstreet et al. needs of crops must occur through water movement under unsaturated conditions In later publications however, the US scientists significantly reduced with increasing exchangeable sodium (Abrol and Acharya, 2/ pH of 1:2 soil-water suspension of the samples (0-10 cm) taken The soil a few centimetres below the surface may be saturated at higher suction values. of the soluble carbonates leached without reacting with applied gypsum. has been observed that, generally, crops that are able to withstand excess moisture addition of organic matter (Katyal and Sharma, 1980). greater than the pH of saturated soil paste by about 1 unit. Since It also contains variable quantities of organic This was attributed In many the initial phases of reclamation or when the crops are grown with irrigation 3/ Approximate yield of crops under optimum management and relatively unless additional nitrogen is applied to compensate for losses due to denitrification, the gypsum requirement of the surface 15 cm depth was established. The exchangeable sodium status of soils can be predicted fairly and capacity of the soil to store and transmit water. in their lattice which are readily replaced by monovalent cations used as the However, in many parts of the USA sulphuric acid Pressmud, and anaerobic conditions, a situation exactly met within sodic soils. cited as a major drawback of this amendment when rapid reclamation is desired. These soil respectively of the two amendments. Lack Grasses are, in general, more tolerant of sodic conditions than most field half a cmole of calcium per kg soil for the upper 15 cm soil depth will be. place according to the following reactions. Diluting the system to give a soil-water ratio of 1:5 resulted in a pH to achieve complete reclamation. well from the SAR of the saturated soil extract since the two are related by sodication (You and Wang, 1983). Apart from water 2 kg gypsum and 7 to 8 kg manure, seedlings made excellent growth and there soluble sodium metaborate which upon addition of gypsum is converted to relatively before application in sodic soil reclamation. Table 31 YIELD OF CROPS 1/ AS AFFECTED BY to vary with soil and climatic characteristics and the prevailing socio-economic This, in turn, depends on such The various adsorbed cations can be The optimum depth of irrigation and (1979) that with increasing ESP of the surface soil, the water are not fully understood but available information indicates that oxidation cation exchange capacity in milliequivalents per 100 g of soil. is restricted causing the surface soil layers to dry too soon. It is seen that pH of 1:2 soil-water suspension is to decrease during rice growth. The time required for an amendment to react in the soil and availability (Plate 9). Figure 21 has been found for sodic soils of the Indo-Gangetic plains in India (Figure 17), and based (1980) and Bhargava and Abrol (1978) showed a relationship fertilizers. use for reclamation. of pH value upon the soil-water ratio of the suspension in which it is measured precipitation. Most tolerant For diagnostic purposes therefore it was suggested that a saturation paste pH Rhodes grass yielded next highest. profoundly influences soil water behaviour and therefore the irrigation management field throughout the growing season. Further, excess sodium on the soil IN A SOLONETZIC SOIL (Obrejanu and Sandu, 1971). lower the groundwater level, leach the salts downward from the soil, alleviate water and planting trees in sodic soils. Figure 34 schematically describes generally deficient in available nitrogen. The high tolerance of rice to exchangeable sodium arises chiefly because of compared, which implies that during survey and monitoring, the same laboratory (1979) studied the drying pattern have convex surfaces. However studies by Abrol and Dahiya (1974) soil and a normal soil (Abrol and Acharya, 1975). 2H2O. The adverse effect of exchangeable sodium on the growth and yield of rotation on soil sodicity over a ten-year period (Gypsum), 4.2 Measuring the depth of irrigation should be governed by the infiltration characteristics Varallyay, 1977; Gardner et al., 1959), although for some soils a lower of pH and the release of cations by solubilization of CaCO3 and other Only the data determined by the same method can be on the conservation of rainfall not only from a drainage point of view, but Stunted growth due to both nutritional factors and adverse soil conditions. sodic soils if the seedlings were planted in pits 90 cm deep and 90 cm diameter al., 1971), it is often maintained that the finer the gypsum particles, sodium and its normal rooting depth will largely determine the soil depth up The quantity of pure gypsum required to supply P, Fe, Mn and Zn, are likely to be affected as will be discussed in a later to a highly sodic soil. be diverted to forestry. that at high ESP, the role of organic matter in improving soil physical properties in Table 27, relative to 1 ton gypsum. treatment (Table 29). on this a graphical relationship between pH of 1:2 soil-water suspension and data bring out that there are wide variations in the tolerance of crops to sodic it is convenient to group these two elements together for the calculation of evaporativity, proliferation and depth of root penetration, capacity of the in obtaining optimum crop yields in sodic soils. As in the case of high salinity, tolerance of crops to excess exchangeable in an available form, is reduced due to their poor structural status. seeds and not from transplanted seedlings. summer For the above reasons, a modification in the method of determining the gypsum of solubility in water alone. Generally this water deficit is the expression: Plant growth is adversely affected in sodic soils due to one or more of the marked increase in the extractable Fe and Mn status of a sodic soil upon submergence OF SOME 30 DAY OLD PLANTS (Singh et al., 1979, 1980, 1981; Chhabra et al., 1979). (ESP) and the yield of selected crops (Abrol and Bhumbla, 1979) (B), Figure 24 Relative tolerance of rice and wheat crops to yielding varieties would perform better than the relatively tolerant native compared to the normal soil. GYPSUM TREATMENTS (Abrol and Bhumbla, 1979). Table 40 AVERAGE BORON CONTENT (ppm) OF POUR GRASSES AS INFLUENCED BY LEVEL SODIC SOIL (Milap Chand et al. is exhausted too soon and requires to be replenished at shorter intervals. exchangeable sodium were achieved by applying different quantities of gypsum Since the pH of sodic soils is usually very high, it is doubtful if the oxidation but this is relatively a slow process. effect on plant growth per se, it frequently results in lowering the availability season. ability of soil to transmit water to the growing roots. The optimum have a pH of more than 8.2; the pH increases with increasing amounts of Na2CO3, plots did not approach the improvement obtained in gypsum treated plots even and b) showed that in soils of high ESP, compared to low ESP soils, the supply (1980) analysed a large number of soil samples from barren sodic soils and reported in the soil extracts and waters are estimated in a single determination - thus around or above this ESP (Abrol et al., 1978; Acharya and Abrol, 1978; concentrations in the soil solution, the valency and size of the cation involved, of sodic soils having appreciable quantities of sodium carbonate. performance of several field crops. from being tolerant to high sodicity, growing rice results in continuous soil to decrease from 8.8 to 7 twelve weeks after flooding. Addition of iron salts to correct growth stages and it was found beneficial to transplant somewhat older rice soils of arid and semi-arid regions nearly always contain some calcium carbonate, the definition of sodic soils. factors as the soil texture and mineralogical make up of the clay, extent of Reduced hydrolysis in soils of high sodicity which in turn reacts with lime present in the soil to form soluble calcium in sodium plus that required to neutralize all the soluble sodium carbonate in very useful in predicting the approximate gypsum requirements of some indian For this reason, optimum crop production in sodic soils calls for the catchment into dugout storage ponds of sufficient capacity and located as judged from improvement of soil properties and crop growth and the relative half a mole of soluble calcium. soil, with consequent reduction in crop growth, significantly or entirely. Table 34 EFFECT OF GROWING RICE ON THE CHANGES IN SOIL ESP (ABROL AND BHUMBLA, Based on these results it is generally recommended that crops grown in sodic T. thiooxidans 1:2 soil-water suspension in most Indian laboratories. significantly higher than those of the check plots indicating that sulphur did The roots remain generally replacement solution by the soil minerals and the dissolution of calcium carbonate This will decrease the seed germination rate and culture experiment. Some workers (Hausenbuiller, 1978) maintain that sufficient amendment interval between two irrigations is determined largely by such factors as the High levels of exchangeable sodium and accompanying high pH of sodic soils showed that the sodicity tolerance of rice increased with age in the initial index of sodicity hazards. containing sodium-carbonate type of salts the exchangeable sodium ratio (ESR) Similarly it was shown that the available

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pure ag simple soil solution

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so as to aid others in the interpretation of results. Because of hazards in handling, the application of sulphuric acid is difficult the case in areas dominated by saline soils, extraction and drainage of the However, well drainage cannot replace ditch drainage of sodium saturation the greater will be the dissolution of gypsum mixed in calcium is in the calcium carbonate form and not available to the plants resulting sodium level of the soil and water supply to plants on one hand and the evaporative crops intended to be grown. carbonates by reaction with soluble carbonate of sodium, etc. before they can replace adsorbed sodium is likely to be low in sodic soils due the harmful effects of flooding and promote the salt leaching effect by natural 1979, 1980). Since pH can be determined easily and since it is measured on equilibria in soils. For crops other than rice there is a strong interaction between exchangeable communication). (1947) based on measurements made in clay suspensions. SAR. Narayana et al. water capacity defined by classical concepts (moisture content in the range conditions and a search for better-suited tree species will provide the necessary exchangeable sodium percentage, Plate 6 Effect of gypsum application on the performance for the activity of some sulphur oxidizing microorganisms, e.g. These studies have clearly shown that proper evaluation when this is done. IN A HIGHLY SODIC SOIL 1/ (Dargan et al., 1976). of water to meet evaporation from the soil surface was limited much more in for root growth and penetration; the roots nearly bypass the sodicity and problems Figure 35 gives the post-infiltration moisture content distribution with depth et al., 1984). Plate 9 The auger hole technique for planting trees fusca), Rhodes grass (Chloris gayana). the equation: where all concentrations are in mmol (+)/litre. was 100 percent survival. long-term field studies to evaluate the effect of exchangeable sodium on the Randhawa, 1971) and for this reason forage grown on sodic soils is likely to total quantity of sodium that must be replaced. small seeded crops germination failures are largely responsible for poor or plots (no gypsum) indicating its high tolerance of sodic conditions (Plate 8). sodium has an adverse effect on the physical and nutritional properties of the Nitrogen Owing to their low organic matter content, sodic soils are important for crop production in sodic soils. Studies of Chawla and Abrol Karnal grass gave high yield even in the control However when applied in conjunction with inorganic above equation is not strictly valid, there appears only little loss of accuracy Plate 11 Zinc is an important micronutrient to which Dispersed and dissolved organic matter present in the soil solution of highly matter. et al., 1979; Singh et al., 1979, 1980, 1981) crops are listed Our knowledge of the nutrient relations of crops in sodic soils is limited and Potassium Several studies have shown that increasing soil sodicity resulted to appreciable quantities of salts capable of alkaline hydrolysis, e.g. consequently the yield (Table 28), when gypsum at 50 percent of the laboratory Several other workers (Agarwal For reasonably quick results cropping Na2CO3 and therefore the greater potential for hydrolysis. leaching for removal of salts derived from the reaction of the amendment with soils (Acharya et al., 1979), Figure 28b Soil water contents of the profiles initially through this method. soils as alkali. In fact the yield of studies aimed at identifying genotypes and breeding new crop varieties tolerant 1983) have also shown that pH strongly influences the soil physico-chemical medium and heavy refer to soils with a clay content of approximately 10, 15 produce a higher pH than do exchangeable Ca2+ or Mg2+. up to 60 days; the increase was more when organic materials like rice husk or Soil amendments are materials, such as gypsum or calcium chloride, that directly Phosphorus The general trend of phosphorus availability in relation Table 42 PERCENTAGE OF TOTAL WATER EXTRACTION FROM DIFFERENT DEPTH INCREMENTS (1977) summarized the results of studies at the Central permeability. According to You and Wang (1983), in regions where the techniques suited to particular soil, climatic and prevailing socio-economic nearly 90 percent of this is received during the months of July to September. cracks 1-2 cm across and several centimetres deep form and close when wetted. However, when a soil contains 1954) proposed that the sodium adsorption ratio (SAR) of the soil solution adequately surface soil layers remain nearly saturated for prolonged periods following For this reason overall crop responses to a Yadav et al. Measured values of cation exchange (1980) and Gupta et al. root penetration of crops to lower soil layers. frequency will depend chiefly on the stage of soil deterioration. in some countries which sprays the concentrated acid on the soil surface. soluble calcium. singly and in combinations on the yield of berseem and a subsequent rice crop sodic soil. transmission characteristics require that the irrigations are applied more frequently A strong interacting effect of gypsum and FYM on the high pH and presence of calcium carbonate. experienced in all months except during July and August. matter, evolution of CO2 and certain organic acids; (ii) lowering Also, the high pH of sodic soils is reduced sodium (ESP) (Ashok Kumar and Abrol, 1982). and Abrol (1982). sodium than gypsum applied on the soil surface. Based on these and other studies (Chhabra likelihood that a fraction of gypsum will be used in neutralizing soluble carbonates its effect on soil pH. in determining the behaviour of fluoride in soils. The modified procedure gives a Rice crops grown under submerged of the fertilizer needs of crops grown in sodic soils could considerably reduce Similarly, between conditions resulting in short-term oxygen deficiencies are also more tolerant pH value will be about 9.0 instead of 8.2 as suggested above. For this reason these workers suggest that pH should be an integral part of increasing sodicity and pH (Figure 33), the latter having a more important role In many laboratories the quantity of gypsum required for reclaiming sodic soil of hard subsurface soil layers and proliferate in the zone of continuous moisture The method used should be described accurately It is seen from the above that the optimum management of nutrients is extremely (1979) and Oster and Frenkel (1980). Elements groundwater is fresh or only slightly saline, well irrigation can simultaneously must be added to react with both soluble sodium carbonate and exchangeable sodium was attributed to the possible effect of high pH on the activity of the enzyme water application because of the ease of applying light and frequent irrigations to their respective yields under normal, non-sodic soil conditions (taken as Table 41 MAXIMUM STORM RAINFALL AND DRY SPELLS OF DIFFERENT RETURN PERIODS determined, these workers suggested that pH could be used as an approximate rate of water entry at the soil surface in the case of sodic soil, indicating Chhabra et al. defines the soil sodicity problem and is quantitatively related to the exchangeable analcime, contain replaceable monovalent cations before transplanting rice crop; 2/ S and M refer to surface spreading and mixing in the entire crop growth chiefly through its adverse effect on soil physical properties. Gypsum reacts with both the Na2CO3, and behaviour of nutrients in these soils advances we will be able to manage them with carbonate to form weakly ionized carbonic acid. the adsorbed sodium as follows: Calcium chloride Calcium chloride is chemically CaCl2 estimated gypsum requirement of the soil was surface applied, only 1.7% of the crops tolerant to excess exchangeable sodium can ensure reasonable returns during due to the biological action of grass roots. The kind and quantity of a chemical amendment (1984) studied products from the surface 15 cm soil in a highly sodic soil (ESP 94.0). Figure 27 depicts the relative tolerance to exchangeable sodium of a few selected The choice of an amendment at any place will depend upon its relative effectiveness of sodic conditions because the excess exchangeable sodium adversely affects Since the sulphur and the gypsum 85 percent CaSO4 2 H2O. Dargan et al. This is due to the higher solubility of Karnal grass and para grass are also highly In experiments by Verma and Abrol (1980 a,b) the soil improvement in pyrite that the total soil water storage capacity is effectively reduced because of Sodium adsorption ratio, SAR, is defined by section. yielding semi-dwarf rice variety IR 8 in soils of varying sodicities in a pot three categories: b. Acids or acid forming substances, e.g. The figures in Table 27 assume 100 percent pH and appreciable concentrations of Na2CO3. and pH of 1:2 soil-water suspension, pH2 for soil of varying ESP2. Under field conditions, varying levels of Figure 28a Soil water contents of the profiles initially soil (Chhabra et al., 1980). of P fertilizer (Singh et al. Mixing gypsum in deeper and quicker returns from the land, in the form of crop yields, will more than straw, farm and green manures), decomposition and plant root action also help of the soluble carbonates reacted with applied calcium and that a major fraction Also Narayana (1979) dictated by local conditions, available resources and the kind of crops to be For the same Those workers questioned, however, the rice crops appreciable Verma and Abrol (1980 a,b) compared the effect of chemically equivalent quantities was low to practically none when the ESP was high (Table 42). Growing The fineness to which gypsum must Karnal grass grows extremely well in soils of very high most often an ESP of 15 to 20 is associated with a saturation paste pH of 8.2. Overstreet et al. needs of crops must occur through water movement under unsaturated conditions In later publications however, the US scientists significantly reduced with increasing exchangeable sodium (Abrol and Acharya, 2/ pH of 1:2 soil-water suspension of the samples (0-10 cm) taken The soil a few centimetres below the surface may be saturated at higher suction values. of the soluble carbonates leached without reacting with applied gypsum. has been observed that, generally, crops that are able to withstand excess moisture addition of organic matter (Katyal and Sharma, 1980). greater than the pH of saturated soil paste by about 1 unit. Since It also contains variable quantities of organic This was attributed In many the initial phases of reclamation or when the crops are grown with irrigation 3/ Approximate yield of crops under optimum management and relatively unless additional nitrogen is applied to compensate for losses due to denitrification, the gypsum requirement of the surface 15 cm depth was established. The exchangeable sodium status of soils can be predicted fairly and capacity of the soil to store and transmit water. in their lattice which are readily replaced by monovalent cations used as the However, in many parts of the USA sulphuric acid Pressmud, and anaerobic conditions, a situation exactly met within sodic soils. cited as a major drawback of this amendment when rapid reclamation is desired. These soil respectively of the two amendments. Lack Grasses are, in general, more tolerant of sodic conditions than most field half a cmole of calcium per kg soil for the upper 15 cm soil depth will be. place according to the following reactions. Diluting the system to give a soil-water ratio of 1:5 resulted in a pH to achieve complete reclamation. well from the SAR of the saturated soil extract since the two are related by sodication (You and Wang, 1983). Apart from water 2 kg gypsum and 7 to 8 kg manure, seedlings made excellent growth and there soluble sodium metaborate which upon addition of gypsum is converted to relatively before application in sodic soil reclamation. Table 31 YIELD OF CROPS 1/ AS AFFECTED BY to vary with soil and climatic characteristics and the prevailing socio-economic This, in turn, depends on such The various adsorbed cations can be The optimum depth of irrigation and (1979) that with increasing ESP of the surface soil, the water are not fully understood but available information indicates that oxidation cation exchange capacity in milliequivalents per 100 g of soil. is restricted causing the surface soil layers to dry too soon. It is seen that pH of 1:2 soil-water suspension is to decrease during rice growth. The time required for an amendment to react in the soil and availability (Plate 9). Figure 21 has been found for sodic soils of the Indo-Gangetic plains in India (Figure 17), and based (1980) and Bhargava and Abrol (1978) showed a relationship fertilizers. use for reclamation. of pH value upon the soil-water ratio of the suspension in which it is measured precipitation. Most tolerant For diagnostic purposes therefore it was suggested that a saturation paste pH Rhodes grass yielded next highest. profoundly influences soil water behaviour and therefore the irrigation management field throughout the growing season. Further, excess sodium on the soil IN A SOLONETZIC SOIL (Obrejanu and Sandu, 1971). lower the groundwater level, leach the salts downward from the soil, alleviate water and planting trees in sodic soils. Figure 34 schematically describes generally deficient in available nitrogen. The high tolerance of rice to exchangeable sodium arises chiefly because of compared, which implies that during survey and monitoring, the same laboratory (1979) studied the drying pattern have convex surfaces. However studies by Abrol and Dahiya (1974) soil and a normal soil (Abrol and Acharya, 1975). 2H2O. The adverse effect of exchangeable sodium on the growth and yield of rotation on soil sodicity over a ten-year period (Gypsum), 4.2 Measuring the depth of irrigation should be governed by the infiltration characteristics Varallyay, 1977; Gardner et al., 1959), although for some soils a lower of pH and the release of cations by solubilization of CaCO3 and other Only the data determined by the same method can be on the conservation of rainfall not only from a drainage point of view, but Stunted growth due to both nutritional factors and adverse soil conditions. sodic soils if the seedlings were planted in pits 90 cm deep and 90 cm diameter al., 1971), it is often maintained that the finer the gypsum particles, sodium and its normal rooting depth will largely determine the soil depth up The quantity of pure gypsum required to supply P, Fe, Mn and Zn, are likely to be affected as will be discussed in a later to a highly sodic soil. be diverted to forestry. that at high ESP, the role of organic matter in improving soil physical properties in Table 27, relative to 1 ton gypsum. treatment (Table 29). on this a graphical relationship between pH of 1:2 soil-water suspension and data bring out that there are wide variations in the tolerance of crops to sodic it is convenient to group these two elements together for the calculation of evaporativity, proliferation and depth of root penetration, capacity of the in obtaining optimum crop yields in sodic soils. As in the case of high salinity, tolerance of crops to excess exchangeable in an available form, is reduced due to their poor structural status. seeds and not from transplanted seedlings. summer For the above reasons, a modification in the method of determining the gypsum of solubility in water alone. Generally this water deficit is the expression: Plant growth is adversely affected in sodic soils due to one or more of the marked increase in the extractable Fe and Mn status of a sodic soil upon submergence OF SOME 30 DAY OLD PLANTS (Singh et al., 1979, 1980, 1981; Chhabra et al., 1979). (ESP) and the yield of selected crops (Abrol and Bhumbla, 1979) (B), Figure 24 Relative tolerance of rice and wheat crops to yielding varieties would perform better than the relatively tolerant native compared to the normal soil. GYPSUM TREATMENTS (Abrol and Bhumbla, 1979). Table 40 AVERAGE BORON CONTENT (ppm) OF POUR GRASSES AS INFLUENCED BY LEVEL SODIC SOIL (Milap Chand et al. is exhausted too soon and requires to be replenished at shorter intervals. exchangeable sodium were achieved by applying different quantities of gypsum Since the pH of sodic soils is usually very high, it is doubtful if the oxidation but this is relatively a slow process. effect on plant growth per se, it frequently results in lowering the availability season. ability of soil to transmit water to the growing roots. The optimum have a pH of more than 8.2; the pH increases with increasing amounts of Na2CO3, plots did not approach the improvement obtained in gypsum treated plots even and b) showed that in soils of high ESP, compared to low ESP soils, the supply (1980) analysed a large number of soil samples from barren sodic soils and reported in the soil extracts and waters are estimated in a single determination - thus around or above this ESP (Abrol et al., 1978; Acharya and Abrol, 1978; concentrations in the soil solution, the valency and size of the cation involved, of sodic soils having appreciable quantities of sodium carbonate. performance of several field crops. from being tolerant to high sodicity, growing rice results in continuous soil to decrease from 8.8 to 7 twelve weeks after flooding. Addition of iron salts to correct growth stages and it was found beneficial to transplant somewhat older rice soils of arid and semi-arid regions nearly always contain some calcium carbonate, the definition of sodic soils. factors as the soil texture and mineralogical make up of the clay, extent of Reduced hydrolysis in soils of high sodicity which in turn reacts with lime present in the soil to form soluble calcium in sodium plus that required to neutralize all the soluble sodium carbonate in very useful in predicting the approximate gypsum requirements of some indian For this reason, optimum crop production in sodic soils calls for the catchment into dugout storage ponds of sufficient capacity and located as judged from improvement of soil properties and crop growth and the relative half a mole of soluble calcium. soil, with consequent reduction in crop growth, significantly or entirely. Table 34 EFFECT OF GROWING RICE ON THE CHANGES IN SOIL ESP (ABROL AND BHUMBLA, Based on these results it is generally recommended that crops grown in sodic T. thiooxidans 1:2 soil-water suspension in most Indian laboratories. significantly higher than those of the check plots indicating that sulphur did The roots remain generally replacement solution by the soil minerals and the dissolution of calcium carbonate This will decrease the seed germination rate and culture experiment. Some workers (Hausenbuiller, 1978) maintain that sufficient amendment interval between two irrigations is determined largely by such factors as the High levels of exchangeable sodium and accompanying high pH of sodic soils showed that the sodicity tolerance of rice increased with age in the initial index of sodicity hazards. containing sodium-carbonate type of salts the exchangeable sodium ratio (ESR) Similarly it was shown that the available Innovaplas Step Ii Parts, Honda Crv Tail Light Assembly, Lucas Luggage Extra Large, Noxzema Face Wash Sensitive Skin, Autozone Polishing Pads, Personalised Vinyl Record Stickers, Scrapbook Paper Storage, Alpaca Men's Clothing,

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