Abstract
The study involved distribution of nutrient elements in the acid soils of mango orchards. The objectives were to evaluate pH, organic carbon, and available macronutrient and diethylene triamine pentaacetic acid (DTPA)-micronutrient content in the soil profile. Depth wise (0–30, 30–60, 60–90, and 90–120 cm) soil samples were collected from 27 different mango orchards comprising of three health levels (unhealthy, medium, and healthy) and three age groups (1–3 years, 4–5 years, and 6–7 years). The pH of the surface soil was low and gradually increased with an increase in depth irrespective of health and age levels of the orchard. The pH was higher under the healthy orchard of 4–5 years old (6.00 at surface layer) and recorded 30% more compared to control (unhealthy orchard of 1–3 years old). The organic carbon was highest of 6.3 and 6.2 g kg−1 in A3H3 (healthy orchard of 6–7 years old) and A2H3 (healthy orchard of 4–5 years old), respectively, in the surface soil layer. The N content was higher under A1H3 (healthy orchard of 1–3 years old), A2H3, and A3H3 (142.2, 138, and 138 kg ha−1, respectively, in surface layer); whereas P and K were higher under A2H3 and A3H3 orchard (12 and 380.5 kg ha−1, respectively, in surface layer) than other orchards. The DTPA-extractable Fe and Mn contents were high status throughout the soil profile; whereas DTPA-extractable Zn and Cu were higher under A2H3 orchard (0.48 and 1.39 mg kg−1, respectively, in surface layer).
INTRODUCTION
The state of Jharkhand, India is endowed with a climatic condition that is conducive for successful cultivation of a diversity of horticultural crops and is dominated by red and lateritic soils. Jharkhand state with an average rainfall of 1372 mm per annum and undulating topography coupled with light texture soil suffers from excessive run-off causing soil and water conservation problems in the region. This region has production constraints: soil erosion and acidity, moisture deficiency, and low availability of nutrients especially of phosphate are the most important in the uplands. Erratic rainfall, lack of irrigation facilities, poor water retentive capacity, and permeability of the soils are the major problems limiting successful double-cropping.
Acid soil infertility is a major limitation to crop production on highly weathered and leached soils in both tropical and temperate regions of the world (Von Uexküll and Mutert, Citation1995). In addition, soil acidification induced by the activities of mankind has become of increasing concern in recent years. Two fundamental factors limit the fertility of acid soils: nutrient deficiencies, e.g., P, Ca, and Mg, and the presence of phytotoxic substances, e.g., soluble Al and Mn. The practice of liming acid soils, i.e., applying CaCO3, in order to raise soil pH and precipitate exchangeable Al as insoluble hydroxy—Al has long been recognized as necessary for optimum crop production (Haynes, Citation1984). The low P status of highly weathered acid soils is a particular problem, because large amounts of P need to be applied in order to raise concentrations of available soil P to an adequate level (Sanchez and Uehara, Citation1980). This is because such soils contain large quantities of Al and Fe hydrous oxides, which have the ability to adsorb P onto their surfaces. Thus, much of the added P is ‘fixed’ and is not readily available for crop use.
Among the fruit crops, mango is widely cultivated in the state of Jharkhand, India. At present, the total land area under mango cultivation is about 50,000 ha in the Jharkhand state (Kumar, Citation2011). The productivity of fruits in the Jharkhand state is around 9.8 t ha−1, which is less than the national average of 11.9 t ha−1. It has been observed that most of the mango plantations (1st year to 6th year) are unhealthy and have a low yield. It is necessary to have a proper soil fertility evaluation before expansion of an area under a fruit-based cropping system in the acid soils. The soil fertility evaluation can forecast for a suitable fruit-based cropping system in the state. Considering all of the above points our investigation was undertaken with the objective to evaluate the major and micronutrient content of different mango orchards grown in acid soils of Jharkhand, India.
MATERIALS AND METHODS
The different mango orchards of Gumla and Lohardaga district of Jharkhand state, India were evaluated for major and micronutrient status during 2011–12. The different mango orchards have been classified based on age (1–3, 4–5, and 6–7 years old) and health (unhealthy, medium, and healthy). The health conditions of the plant were decided by visual observations. The mango plants were planted in a pit size of 45 × 45 × 45 cm3 in respective orchards throughout the state of Jharkhand. There were nine different combinations of mango orchards and the treatments are: A1H1: Unhealthy orchard of 1–3 years old (Control); A1H2: Medium orchard of 1–3 years old; A1H3: Healthy orchard of 1–3 years old; A2H1: Unhealthy orchard of 4–5 years old; A2H2: Medium orchard of 4–5 years old; A2H3: Healthy orchard of 4–5 years old; A3H1: Unhealthy orchard of 6–7 years old; A3H2: Medium orchard of 6–7 years old; and A3H3: Healthy orchard of 6–7 years old. Each combination of orchard was replicated thrice and there were 27 different combinations of orchard for the study. The experiment was set up in randomized block design with factorial concept.
The soils of the region are dominated by red and lateritic soils belonging to the order alfisols. The soils were collected at different depths of 0–30, 30–60, 60–90, and 90–120 cm from different soil profiles covering all of the 27 different mango orchards. The soil samples were then air-dried, powdered, and sieved through an 80-mesh nylon sieve and analyzed for its different chemical properties. The soil organic carbon content was determined by the Walkley and Black method (Citation1934). The following methods were used to determine available nutrient contents: the method of Subbiah and Asija (Citation1956) for N, that of Bray and Kurtz (Citation1945) for P, and the flame photometric method (Jackson, Citation1973) for K. The diethylene triamine pentaacetic acid (DTPA)-extractable Fe, Mn, Cu, and Zn were measured with an atomic absorption spectrophotometer by following the method of Lindsay and Norvell (Citation1978).
All of the data were analyzed by analysis of variance (ANOVA). Multiple comparisons were performed with Duncan’s multiple range test using the MSTATC statistical computer program (version 5; Michigan State University, East Lansing, MI, USA).
RESULTS AND DISCUSSION
pH of the Soil
The pH of the soils of different orchards gradually increased with an increasing depth of soil profile to 120 cm (). Among the health levels of the orchard irrespective of age, the pH of unhealthy (H1) and medium orchards (H2) was below the critical limit of a pH of 5.5, conducive for the growth of mango (Bopaiah and Srivastava, Citation1984) throughout the soil profile. The pH of the healthy orchards (H3) was significantly better than the unhealthy orchard (H1) up to 60 cm depth of soil profile and varied from 5.49–5.93. The pH of the unhealthy and medium orchards was at par throughout the depth of soil profile. Among the age levels of the orchard irrespective of health condition, the pH of the 6–7-year-old (A3) orchard was significantly better than the 1–3-year-old orchard (A1) and was at par with the 4–5-year-old orchard (A2). The pH of the 4–5- and 6–7-year-old orchards was above the critical limit for the growth of mango. The increased pH with increasing depth of soil profiles was ascribed to the deposition of exchangeable bases at lower depth of soil profiles resulting from heavy rainfall in the region during the rainy season (Balpande et al., Citation2007). Comparing the interaction effect of health condition and age of plant, the pH of the soil gradually increased with increasing depth of soil profile irrespective of different mango orchards. The healthy orchard of 4–5 years old recorded the highest pH of the soil throughout the entire depth of soil profile and was significantly higher than the unhealthy orchard of 1–3 years old. The highest pH values of 6.07, 6.81, 6.9, and 6.77 were recorded in the healthy orchard of 4–5 years old at 0–30, 30–60, 60–90, and 90–120 cm, respectively. The healthy orchard of 4–5 years old was statistically at par with the unhealthy orchard of 6–7 years old, medium orchard of 6–7 years old, and healthy orchard of 6–7 years old at 0–30 and 90–120 cm depth of soil profile.
TABLE 1 pH Status of Soils Analyzed for Different Mango Orchards in Alfisols of Jharkhand State, India
TABLE 2 Organic Carbon Content of Soils Analyzed for Different Mango Orchards in Alfisols of Jharkhand State, India
Organic Carbon
The organic carbon content of unhealthy (H1), medium (H2), and healthy orchards (H3) was gradually decreased with increasing depth of soil profile (). The organic carbon content of healthy and medium orchards was significantly better than unhealthy orchards. All of the soils of different orchards had organic carbon below the critical concentration of 5 g kg−1 except the healthy orchard at 0–30 cm depth. The medium and unhealthy orchards were statistically at par on organic carbon content at 0–30, 60–90, and 90–120 cm depth. The organic carbon content of healthy orchards decreased from 5.4 to 2.46 g kg−1 throughout the depth of soil profile. Considering the age levels, the 4–5- and 6–7-year-old orchards were significantly better than the 1–3-year-old orchards on organic carbon content. The organic carbon content of 4-5-year-old orchards was statistically at par with 6–7-year-old orchards at 0–30 cm depth, and again the same orchard was not statistically different with the 1–3-year-old orchards at a lower depth of profile. It has been observed that the organic carbon content of surface soil of 4–5- and 6–7-year-old orchards was above critical concentration. Higher build-up of soil organic carbon on surface layers under the higher age orchard may be attributed to the accumulation of litter of tree species on the soil surface. The subsequent decomposition and incorporation of litter into the soil would have helped in raising the organic carbon status of soil. The results of our investigations were in agreement with the findings of Gill et al. (Citation1987) and Kumar et al. (Citation1998). The interaction effect showed that the organic carbon content gradually decreased with increasing depth of soil profile. The healthy orchard of 4–5 years old, unhealthy orchard of 6–7 years old, medium orchard of 6–7 years old, and healthy orchard of 6–7 years old were significantly better than the unhealthy orchard of 1–3 years old throughout the depth of soil profile. The younger age orchards (1–3 years old) with all its health levels were statistically at par on organic carbon content. The highest organic carbon content was recorded in the healthy orchard of 6–7 years old and was decreased from 6.3 to 3.0 g kg−1 throughout the depth of profile. The healthy orchard of 6–7 years old recorded 84.7% increase in organic carbon over the unhealthy orchard of 1–3 years old and was statistically at par with medium orchard of 6–7 years old and healthy orchard of 4–5 years old at surface soil (0–30 cm).
Available Macronutrients
The available N content of unhealthy, medium, and healthy orchards was gradually decreased with increasing depth of soil profile (). The medium and healthy orchards recorded significantly higher available N over unhealthy orchards throughout the depth of soil profile. The highest available N content was recorded in the healthy orchard and resulted in 20.5, 20.25, 46.8, and 50.1% increase over unhealthy orchards at 0–30, 30–60, 60–90, and 90–120 cm depth, respectively. The available N content of all the orchards was below the critical concentration of 280 kg ha−1 (Subbiah and Asija, Citation1956). The available N content of different age orchards (A1, A2, and A3) was statistically at par throughout the entire depth of soil profile. With increasing depth of soil, the available N content gradually decreased, which was due to the decreasing trend of organic carbon with depth. The interaction effect of different health and age levels of orchards recorded significantly higher available N content over the unhealthy orchard of 1–3 years old (A1H1) throughout the entire depth of soil profile. The highest available N content was 142.2 kg ha−1 in the healthy orchard of 1–3 years old and was statistically at par with the healthy orchard of 4–5 years old and the healthy orchard of 6–7 years old at surface soil. The available N content in all of the orchard combinations gradually decreased with increasing depth of soil profile. The low N concentrations in the soils of all the orchards might be due to N leaching and surface runoff in the undulating topography of different orchards. The highest percent decrease of available N at 90–120 cm depth over its initial value at 0–30 cm was 60.7% in the unhealthy orchard of 4–5 years old.
TABLE 3 Available Nitrogen Content of Soils Analyzed for Different Mango Orchards in Alfisols of Jharkhand State, India
The available P (Bray and Kurtz, Citation1945) content of unhealthy, medium, and healthy orchards was below the critical limit throughout the depth of soil profile (). The healthy orchard recorded significantly higher available P over the unhealthy orchard throughout the depth of soil profile. The unhealthy and medium orchards were statistically at par at all depths of the profile. The healthy orchard registered 102.7, 89.3, 63.6, and 55.5% increase over the unhealthy orchard at 0–30, 30–60, 60–90, and 90–120 cm depth of profile, respectively. Further, the 1–3-, 4–5-, and 6–7-year-old orchards recorded low available P content throughout the depth of soil profile. The available P content in 4–5- and 6–7-year-old orchards was significantly higher over 1–3-year-old orchards throughout the depth of profile. Among the age level of orchards, 4–5-year-old orchards recorded the highest available P in the entire profile. The 4–5-year-old orchards registered 229, 311, 433, and 362% increase over 1–3-year-old orchards at 0–30, 30–60, 60–90, and 90–120 cm depth of profile, respectively. The interaction effect of health and age levels of orchards showed that the available P content of all the orchards was below the critical limit. The available P content gradually decreased with increasing depth of soil profile in all the orchards. The percent decrease of available P at 90–120 cm depth over an initial depth of 0–30 cm was highest of 71.8% in the medium orchard of 1–3 years old. The unhealthy orchard of 1–3 years old, medium orchard of 1–3 years old, and healthy orchard of 1–3 years old were statistically at par and the unhealthy orchard of 4–5 years old, medium orchard of 4–5 years old, healthy orchard of 4–5 years old, unhealthy orchard of 6–7 years old, medium orchard of 6–7 years old, and healthy orchard of 6–7 years old were significantly higher over the unhealthy orchard of 1–3 years old. The highest available P was recorded in the healthy orchard of 4–5 years old throughout the entire depth of soil profile. The low P concentrations in the soils of different orchards might be due to the fixation of released phosphorus by oxides of iron and aluminium (Haynes, Citation1984; Thangasamy et al., Citation2005).
TABLE 4 Available Phosphorus Content of Soils Analyzed for Different Mango Orchards in Alfisols of Jharkhand State, India
The available K content of unhealthy, medium, and healthy orchards gradually decreased with increasing depth of soil profile (). The available K status in all the orchards was found to be in the sufficiency range. The medium and healthy orchards recorded significantly higher available K over the unhealthy orchard. The highest available K was recorded in the healthy orchard and resulted in 26.3, 19.6, 20.7, and 19.0% increase over the unhealthy orchard at 0–30, 30–60, 60–90, and 90–120 cm depth of profile, respectively. The available K content of 1–3-, 4–5-, and 6–7-year-old orchards consistently decreased with increasing depth of profile. The 4–5- and 6–7-year-old orchards recorded significantly higher available K over the 1–3-year-old orchard in the profile up to a depth of 90 cm. The highest available K was recorded in the 6–7-year-old orchard up to 60 cm depth of profile and registered a 44.5 and 30.5% increase over the 1–3-year-old orchard at 0–30 and 30–60 cm depth of profile, respectively. The 4–5-year-old orchard recorded the highest available K and registered 20 and 12.5% increase over the 1–3-year-old orchard at 60–90 and 90–120 cm depth of profile, respectively. The interaction effect of health and age level of orchard showed that the available K content in different orchards gradually decreased with increasing depth of soil profile. The highest percent decrease of available K at 90–120 cm depth over its initial value at 0–30 cm depth was 50.4% in the healthy orchard of 6–7 years old. The interaction effect of all orchard combinations recorded significantly higher available K over the unhealthy orchard of 1–3 years old. The available K content was found to be the highest in the healthy orchard of 6–7 years old in the profile up to 60 cm depth, while the healthy orchard of 4–5 years old recorded the highest available K in the profile at 60–120 cm depth.
TABLE 5 Available Potassium Content of Soils Analyzed for Different Mango Orchards in Alfisols of Jharkhand State, India
The higher content of available nutrients (N, P, and K) on surface layers under different orchards was attributed to accumulation and decomposition of litterfall on the soil surface and subjected to further mineralization of organic N and P from the litter. Higher availability of K at surface layers under different orchards was attributed to liberation of K from decomposition of litterfall as well as solubilization of insoluble forms of K present in the soil due to organic decomposition products. Contractor and Badanur (Citation1996) and Mathew et al. (Citation1997) observed that availability of N, P, and K was higher on surface layers than subsurface horizons under different tree species and it decreased gradually with depth.
TABLE 6 DTPA-Extractable Iron Content of Soils Analyzed for Different Mango Orchards in Alfisols of Jharkhand State, India
DTPA-Extractable Micronutrients
The DTPA-extractable Fe content of unhealthy, medium, and healthy orchards gradually decreased with increasing depth of soil profile (). The highest DTPA-Fe was recorded in the unhealthy orchard throughout the entire depth of profile and was significantly higher over the medium and healthy orchards. All of the orchards showed the Fe content at well above the sufficiency range of 4.5–9.0 mg Fe kg−1 proposed by Lindsay and Norvell (Citation1978) and found in high status. The highest percentage decrease of DTPA-Fe in the healthy orchard over the unhealthy orchard was 47.5, 50, 51.5, and 41% at 0–30, 30–60, 60–90, and 90–120 cm, respectively. It has been observed that the better the health condition of the orchard, the lesser the DTPA-Fe content in the soil profile. The 4–5- and 6–7-year-old orchards recorded significantly higher DTPA extractable-Fe over the 1–3-year-old orchard throughout the entire depth of soil profile. The highest DTPA-extractable Fe was found in both 4–5- and 6–7-year-old orchards and was statistically at par up to 60 cm depth of profile. However, the DTPA-extractable Fe content beyond 60 cm depth was recorded highest in the 4–5-year-old orchard. The highest percentage increase of DTPA-extractable Fe at 0–30 and 30–60 cm depth was 42.7 and 48.9%, respectively, in the 6–7-year-old orchard over the 1–3-year-old orchard. However, the highest percentage of DTPA-extractable Fe at 60–90 and 90–120 cm depth was 48.8 and 81.3%, respectively, in the 4–5-year-old orchard over the 1–3-year-old orchard. Considering the interaction effect of both health and age levels of an orchard, the DTPA-extractable Fe content was highest at 27.8 mg kg−1 in the unhealthy orchard of 6–7 years old and was statistically at par with the unhealthy orchard of 4–5 years old at the surface soil (0–30 cm depth). The DTPA-Fe was recorded highest in the unhealthy orchard of 4–5 years old among the entire orchards and consistently decreased with increasing depth of soil profile.
The DTPA-extractable Mn content of unhealthy and medium orchards was significantly higher over the healthy orchard throughout the entire depth of soil profile (). The highest DTPA-extractable Mn content of 21.38 and 21.13 mg kg−1 was recorded in both unhealthy and medium orchards, respectively, at the surface soil. The DTPA-extractable Mn gradually decreased with increasing depth of profile irrespective of health levels of the orchard. The unhealthy orchard (H1) recorded 22.8, 50.2, 60.3, and 65% increase in DTPA-extractable Mn over the healthy orchard (H3) at 0–30, 30–60, 60–90, and 90–120 cm depth of soil profile, respectively. The DTPA-extractable Mn content in 1–3-, 4–5-, and 6–7-year-old orchards were statistically at par in the surface soil (0–30 cm depth). However, the DTPA-extractable Mn was highest in the 1–3-year-old orchard from 30–90 cm depth of profile compared to 4–5- and 6–7-year-old orchards. The DTPA-extractable Mn consistently decreased with increasing depth of soil profile. The 1–3-year-old orchard recorded an 18.0 and 21.8% increase in DTPA-extractable Mn over the 6–7-year-old orchard at 30–60 and 60–90 cm depth of soil profile, respectively. Considering the interaction effect, the DTPA-extractable Mn content was highest in the surface soil in all of the orchards and gradually decreased with increasing depth of soil profile. The highest DTPA-extractable Mn content of 22.71 mg kg−1 was recorded in the unhealthy orchard of 4–5 years old and was at par with the unhealthy orchard of 1–3 years old, medium orchard of 4–5 years old, unhealthy orchard of 6–7 years old, and the medium orchard of 6–7 years old in the surface soil. The DTPA-extractable Mn content was significantly higher in the unhealthy orchard of 4–5 years old throughout the entire profile depth of 30–120 cm.
TABLE 7 DTPA-Extractable Manganese Content of Soils Analyzed for Different Mango Orchards in Alfisols of Jharkhand State, India
The DTPA-extractable Zn content in all the orchards of unhealthy, medium, and healthy was below the critical limit of 0.6 mg Zn kg−1 (Lindsay and Norvell, Citation1978) throughout the entire depth of soil profile (). The healthy orchard recorded the highest DTPA-extractable Zn content of 0.48 mg kg−1 in the surface soil and was significantly higher than the unhealthy orchard throughout the entire depth of profile. The healthy orchard recorded a 45, 17, 10, and 11% increase in DTPA-extractable Zn over the unhealthy orchard at 0–30, 30–60, 60–90, and 90–120 cm depth of profile, respectively. Among the age levels of the orchard, the DTPA-extractable Zn content in the 6–7-year-old orchard was highest at 0.39 mg kg−1 in the surface soil and was statistically at par with the 4–5- and 1–3-year-old orchards. The DTPA-extractable Zn in the 6–7-year-old orchard was statistically at par with the 4–5-year-old orchard and was significantly better than the 1–3-year-old orchard from 30–120 cm depth of profile. Considering the interaction effect, the highest DTPA-extractable Zn content of 0.48 mg kg−1 was recorded in the healthy orchard of 4–5 years old, healthy orchard of 1–3 years old, and healthy orchard of 6–7 years old in the surface soil and was significantly higher over the unhealthy orchard of 1–3 years old. The DTPA-extractable Zn gradually decreased with increasing depth of profile in all the orchards. The low Zn concentrations in the orchard soils might be due to the fixation of Zn with sesquioxides (Mandal et al., Citation2000).
TABLE 8 DTPA-Extractable Zinc Content of Soils Analyzed for Different Mango Orchards in Alfisols of Jharkhand State, India
The DTPA-extractable Cu content in unhealthy, medium, and healthy orchards gradually decreased with increasing depth of soil profile (). The healthy orchard recorded significantly highest DTPA-extractable Cu content over the medium and unhealthy orchards throughout the entire depth of soil profile. The healthy orchard recorded 66.3, 48.5, 62.7, and 39.6% increase in DTPA-extractable Cu at 0–30, 30–60, 60–90, and 90–120 cm depth of profile, respectively, over unhealthy orchard. The highest DTPA-extractable Cu content was 1.38 mg kg−1 in the surface soil and gradually decreased to 0.81 at 90–120 cm depth of profile in the healthy orchard and resulted in a 41% decrease. Among the age levels of the orchards, the lowest DTPA-extractable Cu content was recorded in the 6–7-year-old orchard throughout the profile. The highest DTPA-extractable Cu content was recorded in the 4–5-year-old orchard and was statistically at par with the 1–3-year-old orchard throughout the entire depth of the profile. Considering the interaction effect, the lowest DTPA-extractable Cu content was observed in the unhealthy orchard of 6–7 years old throughout the profile. The highest DTPA-extractable Cu content was 1.39 mg kg−1 registered in the healthy orchard of 4–5 years old and was statistically at par with the healthy orchard of 6–7 years old and the healthy orchard of 1–3 years old in the surface soil. Further, the Cu content gradually decreased with increasing depth of profile in all the orchard combinations. The highest percent decrease of DTPA-Cu at sub-surface soil (90–120 cm) over its initial value at surface soil (0–30 cm) was 56.8% in the healthy orchard of 6–7 years old.
TABLE 9 DTPA-Extractable Copper Content of Soils Analyzed for Different Mango Orchards in Alfisols of Jharkhand State, India
CONCLUSIONS
The results of our investigation confirmed that organic carbon, available N, available P, and DTPA-extractable Zn content in different mango orchard soils were below critical levels. The chances of nutrient leaching are always more if the level of organic carbon is not maintained through addition of organic matter. Thus, it is very important to add organic and chemical fertilizer to maintain adequate fertility status of these soils. Further, the DTPA-extractable Fe was high up to 90 cm depth of soil profile in all of the orchards. The DTPA-extractable Mn content was high throughout the soil profile depth of 120 cm. The toxic effect of Fe and Mn on the establishment of new mango orchard can be overcome by planting the sapling in a pit size of 90 × 90 × 90 cm3. Among the health levels of orchard, the major and micronutrient status of a healthy orchard was better than the medium and unhealthy orchards. The organic carbon, available N, P, and K content of higher age orchard (4–5 years and 6–7 years) was better than a younger age orchard (1–3 years). The micronutrient status was non significant among the different age group of orchard.
FUNDING
The authors wish to acknowledge Indian Council of Agricultural Research for providing funding and the facility for carrying out this research.
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