Nutrient Index Values Research Articles

Analysis of the Soil Fertility Condition in Jiliba Village, Ganjam District, Odisha

An assessment of soil fertility was conducted in Jiliba village, situated in the Bellaguntha block of Ganjam district in the North-Eastern agroclimatic zone of Odisha, India. Analysis of physical and chemical properties was conducted on soil samples obtained at a depth ranging from 0 to 15 cm. The findings indicate that the predominant soil texture in the hamlet under study consisted of sandy loam and clay loam. The soil hue ranged from Dark Grey at 10 years old to Yellowish brown at 10 years old. The pH of the soil varied from somewhat acidic (5.5-6) to neutral (6.5-7.5). The electrical conductivity of the whole research area remained uniformly below 0.74 dSm-1. Approximately 77.5% of the research region exhibited soil organic carbon (SOC) levels below 0.5%. The available nitrogen concentration was insufficient, varying from 87.8 to 150.5 kg/ha, indicating a possible requirement for nitrogen fertilization to adequately sustain crop development. The phosphorus content in Brays exhibited significant variation, ranging from 4.7 to 198.2 kg/ha, providing evidence of geographic heterogeneity in phosphorus availability throughout the hamlet. The soil potassium level exhibited significant variation, ranging from 54.6 to 435.6 kg/ha, potentially impacting the absorption of nutrients and the production of crops. The Nutrient Index readings for nitrogen (1.0) and phosphorus (1.32) were below expected levels, suggesting the necessity of implementing nutrient management strategies to enhance soil fertility. The potassium Nutrient Index value of 1.87 indicates a moderate level of potassium availability in comparison to nitrogen and phosphorus. The extractable soil sulphur from calcium chloride (CaCl2) ranged from 6.4 to 126.7 kg/ha, underscoring the significance of sulphur for crop fertilization. Modest variations in exchangeable calcium (Ca2+) and magnesium (Mg2+) levels suggest differences in soil cation exchange capacity and nutrient availability. The micronutrient levels exhibited variation, with copper (Cu) concentration ranging from 2.026 to 4.210 parts per million (ppm), zinc (Zn) concentration ranging from 0.736 to 4.440 ppm, manganese (Mn) concentration ranging from 19.0 to 79.0 ppm, and iron (Fe) concentration ranging from 44.36 to 160.64 ppm. The concentration of boron soluble in hot water varied from extremely low to medium (0.15 to 0.68 mg/kg), suggesting different degrees of boron accessibility for plant absorption. Finally, it is essential to fill the research gaps concerning soil fertility and nutrient dynamics in order to establish sustainable agricultural practices and guarantee food security in the region.

Soil Fertility Mapping using Geo-spatial Technique for Khapradih Farm, DKS College of Agriculture and Research Station, Bhatapara, Chhattisgarh, India

The present study aimed to assess various chemical properties and available macro and micronutrients in the soil. Collection of 101 geo-referenced soil surface samples at 100-meter intervals of the Khapradih Farm of DKS College of Agriculture & Research Station, district Balodabazar-Bhatapara of Chhattisgarh state and examined in the laboratory for pH, electrical conductivity (EC), organic carbon (OC), and available macro-nutrients (N, P, K, S) and micro- nutrients (Fe, Mn, Cu, Zn, B). The results showed that the soil was generally neutral in pH, with a range of 5.7 to 7.6. The electrical conductivity indicated non-saline, varying from 0.11 to 0.26 dSm-1. Available nutrients were categorized as low, medium, or high based on nutrient index values. The study revealed that the soil in the area had low levels of available N and S, medium levels of available P and K, and high levels of available Fe, Mn, and Cu. Zn was found to be in the medium category, while B was low. Significant correlations were observed between various physico-chemical properties and available macro and micro nutrients. Using ArcGIS 10.4.1, thematic maps were created, representing the spatial distribution of soil properties and nutrient status. Based on these findings, fertilizer recommendations were developed for major crops grown in the area, resulting in enhanced crop productivity. The study concludes that GPS and GIS-based tools are valuable for soil fertility mapping, monitoring, and site-specific nutrient management, leading to sustainable and optimal crop yields.

Assessment of soil fertility and nutrient management strategies in calcareous soils of Khuzestan province: a case study using the Nutrient Index Value method.

Soil fertility (SF) is a crucial factor that directly impacts the performance and quality of crop production. To investigate the SF status in agricultural lands of winter wheat in Khuzestan province, 811 samples were collected from the soil surface (0-25cm). Eleven soil properties, i.e., electrical conductivity (EC), soil organic carbon (SOC), total nitrogen (TN), calcium carbonate equivalent (CCE), available phosphorus (Pav), exchangeable potassium (Kex), iron (Fe), copper (Cu), zinc (Zn), manganese (Mn), and soil pH, were measured in the samples. The Nutrient Index Value (NIV) was calculated based on wheat nutritional requirements. The results indicated that 100%, 93%, and 74% of the study areas for CCE, pH, and EC fell into the low, moderate, and moderate to high NIV classes, respectively. Also, 25% of the area is classified as low fertility (NIV < 1.67), 75% falls under medium fertility (1.67 < NIV value < 2.33), and none in high fertility (NIV value > 2.33). Assessment of the mean wheat yield (AWY) and its comparison with NIV showed that the highest yield was in the Ramhormoz region (5200kg.ha-1), while the lowest yield was in the Hendijan region (3000kg.ha-1) with the lowest EC rate in the study area. Elevated levels of salinity and CCE in soils had the most negative impact on irrigated WY, while Pav, TN, and Mn availability showed significant effects on crop production. Therefore, implementing SF management practices is essential for both quantitative and qualitative improvement in irrigated wheat production in Khuzestan province.

Nutrient Status of Coastal Soils-24 Parganas (South), West Bengal, India

The study conducted in the year 2023-24 at the Department of Soil Science and Agricultural Chemistry, The Neotia University, 24 Parganas (South), situated in coastal region of West Bengal, aimed to assess the nutrient status of the soils in the instructional farm. Soil samples (105 No) were collected at 0-15 cm depth and analyzed for pH, electrical conductivity (EC), organic carbon (OC), and major nutrients such as available nitrogen, phosphorus, and potassium. The result showed that the soils were neutral in reaction and saline in nature, whereas organic carbon and available nitrogen content were at a medium status, but available phosphorus and potassium status were high. Moreover organic carbon showed negative correlation with soil electrical conductivity (-0.384, p&lt;0.05). The nutrient index values for available nitrogen and available phosphorus were between 1.66-2.33 range, categorizing it as medium fertile. Conversely, the nutrient index value for available potassium exceeded 2.33, classifying it as high fertile.

Physico-chemical properties, available nutrient content and their inter-relationship in soils under rain fed maize-wheat cropping system, district Reasi (J&amp;K)

Composite soil samples representing rain fed maize-wheat cropping system in district Reasi of Jammu and Kashmir were analyzed for important physico-chemical properties and available nutrients. These soils were found to be sandy loam in texture with pH, EC and OC varying from 5.89 to 8.73, 0.04 to 0.47 dS/m and 3.5 to 21.9 g/kg, respectively. Content of available major nutrients viz. N, P, K and S varied from 207.6 to 663.6, 0.89 to 78.0, 22.71 to 349.45 kg/ha and 0.50 to 52.30 mg/kg, respectively, while that of available micronutrients viz. Fe, Zn and B varied from 0.89 to 30.20, 0.18 to 3.85 and 0.11 to 0.70 mg/kg, respectively. As per Nutrient Index values, these soils fell in high category of available Fe, medium category of available N, P, Zn, B and low category of available K and S. Soil pH, EC and OC were significantly and positively correlated with each other as well as with available N, K and B; and negatively with available Zn. Soil pH was also significantly negatively correlated with available Fe whereas, EC was positively correlated with available S and P. Further, available P was significantly positively correlated with OC, available N, K, S, Fe and B. Available N had a synergistic relationship with available K and B; and antagonistic relationship with available Zn. Available Zn showed significant and positive correlation with available Fe; however its correlation with available K and B was significantly negative. Available B had a significant positive correlation with available K and negative correlation with available Fe. The step down regression analysis indicated that nearly whole of variability in available N could be attributed to OC alone. About 28% of total variability in available P could be attributed to pH and EC together; while 13% of that in available S could be attributed to EC alone. Nearly 58 and 82% of the respective variability in available K and B could be due to OC and EC together. Soil pH and OC together contributed about 80 and 86% of the total variability towards available Fe and Zn in order.

Changes in Physicochemical Parameters of Soil Along the Villages in Pendhurti Block of Visakhapatnam District, Andhra Pradesh

Soil represents a critical element of plant existence, ranking prominently among the five essential elements. When soil quality declines, it adversely impacts crop productivity. In the present research, the emphasis was placed on conducting a physicochemical analysis of soils in various villages within the Pendhurti block of Visakhapatnam district. In this research, 30 samples of soil were gathered haphazardly from 0 to 15 cm depth across 15 distinct villages.The soil samples gathered underwent analysis in a laboratory to assess their physicochemical parameters. The results revealed that the soil pH exhibited a neutral to slightly alkaline reaction i.e. 6.9 to 8.2 and EC 0.076 to 0.381. The organic-C content was found to be low i.e. (0.12 to 0.59). The Particle density and bulk density were observed to be 2.05 to 2.8 Mg m-3 and 1.33 to 1.57 Mg m-3. The available N in soil was found lowi.e.75.26 to 137.98 kg ha-1, medium to low for K (78.4 to 389.40), and high for P i.e. (22.38 to 151.98 kg ha-1). The available Ca and Mg were recorded to be adequate and S was low to medium (0.21 to 19.6 mg kg-1) and nutrient index values for N, S, Organic-C found to be low, medium for K and high for P. The available micronutrients were reported sufficient (Cu, Zn) to high (Fe, Mn).This analysis emphasizes the need for a greater emphasis on improving soil quality using enhanced practices such as integrated nutrient management and crop rotations, rather than depending solely on monoculture farming.

Evaluation of Soil Nutrient Status of Regional Research Station Farm, Paiyur, Krishnagiri District, Tamil Nadu, India

Soil fertility evaluation of Regional Research Station farm, Paiyur, Krishnagiri district, Tamil Nadu, India was done for efficient land use planning and crop production. Soil testing provides information on soil available nutrient status and serves as basis for making fertilizer prescription to crops. Soil samples were collected at 0-15 cm depth from each and every field of Regional Research Station farm, Paiyur and analysed for their nutrient status. The results revealed that the farm soils were slightly alkaline (pH 7.69) in reaction, non saline (0.06 dSm-1), low in organic carbon (0.41 per cent) and available nitrogen (238 kg ha-1), high in available phosphorus (24.8 kg ha-1) and medium in potassium (177 kg ha-1) status. The nutrient index value of organic carbon and available nitrogen were &lt;1.66 and categorized under low fertility status. The nutrient index value for available phosphorus &gt;2.33 and categorized under high and available potassium was 1.66-2.33 and grouped under medium category.

Micronutrient Indexing of Soils Located in Attock District of Pakistan: A Guide to Replenish the Nutrient Deficiency

The agricultural land of Attock district falls in Pothwar area of the Punjab Pakistan which is mostly rainfed (barani) and agriculture in the area depends on rainfall which is erratic and scanty. Therefore, soil health becomes more crucial for crop growth while application of micronutrients is negligible in this area. During the years from 2016 to2018, 15,337 soil samples were collected from the district Attack to determine micronutrient status of the soil. These soil samples were analyzed for Zinc (Zn), copper (Cu), Iron (Fe) and Manganse (Mn) using DTPA extraction method while dilute HCl method for Boron (B). The results indicated that nutrient index value of plant available Zn was in the marginal category (1.84) with 30.7% soil samples falling in low, 54.1% in marginal and 15.2% in adequate category. Nutrient index value of plant available Cu was in the adequate category (2.18) with 16.9 % soil samples in low, 47.9% in marginal and 35.2% in adequate category. Nutrient index value of plant available Fe was 1.46 (low) where 76.8% soil samples were found to be low and 23.2% adequate. Nutrient index value of plant available Mn was 1.11 (very low) where 89.3% soil samples were low, 9.9% marginal and only 0.8% adequate. Nutrient index value of plant available B was also in very low category (1.25) with 74.2% soil samples low and 25.8% marginal. The results indicated depletion and low concentration of micronutrient in most soil of Attock district which ultimately urges the use of balanced fertilizer for higher crop yield.

English

The insufficiency of nutrients in the soils has been identified as one of the factors that have affected the productivity of crops. An investigation was carried out to assess the trophic level of soil in the region. Using a non-probability sampling technique, a total of 70 representative surface soil samples were collected between February and April, 2021. The sampling depth ranged from 0 to 30 cm, according to the root length of the crop. The collected soil samples were analyzed to assess the pH, EC, OM, available macronutrients, and micronutrients. The macronutrients were determined using a flame photometer, and micronutrients were determined with ICP-OES. The organic matter status was low in Trenabougou soils. The soils are moderately acidic in reaction (pH 5.84) with low soluble salt content (EC 0.27 dS/m). Some macronutrients were low or medium in fertility status. The nitrogen, potassium, and magnesium nutrient index values were below 1.25, indicating low fertility status. Nevertheless, sulphurous and calcium were found at medium fertility levels with a nutrient index of 1.87 and 2.17. The concentrations of micronutrients like iron, copper, and zinc were high in soils. Nevertheless, nickel, manganese, and boron were in the limited range suitable for plant growth. Key words: Available NPK, Nutrients, Nutrient Index, Siby, Mali.

Characterization of Soil Quality Parameters of Balaghat and Malajkhand Blocks in Balaghat District of Madhya Pradesh, India

The investigation was carried out at the laboratory of Rajiv Gandhi South Campus, Banaras Hindu University, Barkachha; Mirzapur, during the year 2021-2022. This study’s aim was to examine the different soil quality parameters and Nutrient index of the soil in the mining areas and normally cultivated areas in the Balaghat and Malajkhand blocks in the Balaghat district of Madhya Pradesh. With the help of GPS camera, 75 soil samples were taken from farmer fields in 9 villages at a depth of 0-15 cm. The soil samples from both sites were reported to be neutral to slightly alkaline in nature, with mean values of 7.59 and 7.57 for both mining and normal cultivated area, respectively. Electrical conductivity for both the sites was low with a mean value for mining area and normal cultivated area were 0.34 dSm-1 and 0.42 dSm-1. High levels of organic carbon were found in the soil of both mine and non-mining areas, with mean values of 0.83% and 0.98 %, respectively. For all samples from both areas, the bulk and particle densities were within normal range, in mining area bulk density were observed high as compare to normal cultivated area and were observed to have the maximum pore space and water holding capacity. According to the nutrient index values of soil samples of Balaghat and Malajkhand blocks were found to be “Medium” for Phosphorous (1.80) andPotassium (1.99) and “Low” for Nitrogen (1.09) and Sulphur (1.12).

Assessment of Micronutrient Content and Strategies for Improvement of Micronutrient Status in the Soils of Bhandara Tehsil, Maharashtra, India

The study was undertaken to determine the available micro-nutrient status of the Bhandara tehsil of Maharashtra with the help of GPS-based one hundred-and-five soil samples during the period of 2021-2022 from paddy growing fields. Samples were analyzed at the Soil Science and Agricultural Chemistry Section, College of Agriculture, Nagpur. The results revealed that soils were clay loam to sandy clay loam in texture. The study area was slightly acidic to slightly alkaline and non-saline in reaction. The mean values of 0.42 mg kg-1, 5.44 mg kg-1, 6.39 mg kg-1, 0.98 mg kg-1, and 0.90 mg kg-1 for Zn, Fe, Mn, Cu and B respectively, were recorded. The soil nutrient index values showed that available Zn was low; available Fe was moderate; available Mn and B were moderately high; and available Cu was high. The farmers of the study area mostly adopt improper nutrient management practices which might have resulted in poor fertility status in the area. Taking these things into consideration, a data-driven Decision Support System (DSS) on micronutrient management in soil has been given. To address this problem, farmers of Bhandara tehsil may use micronutrient fertilizers or implement soil management practices that promote the uptake and availability of micronutrients to plants.

GIS-based soil fertility assessment of a micro-watershed of semi-arid tropics in southern India

Available macronutrient status in the soil of Chotanahalli micro-watershed (468 ha) in Kunigal Taluk, Tumkur district was studied with the aid of GIS. Forty three surface soil samples at 320 m grid were collected from Chotanahalli micro-watershed and assessed for the soil organic carbon, available nitrogen, phosphorus, potassium, calcium, magnesium and sulphur. Results revealed that the ranges of SOC, available N, P and K were 2.1 to 7.5 g kg-1 , 282.2 to 526.8 kg N ha-1 , 8.0 to 67.6 kg P2O5 ha-1 and 124.3 to 338.5 kg K2O ha-1 , respectively. Spatial interpolation revealed that majority (321 ha) of the watershed was low in SOC, whereas the whole watershed was medium in available N, P and K. In case of secondary nutrients, available S was found to be medium in majority (423.4 ha) of the area, whereas, exchangeable Ca and Mg were found sufficient in the whole watershed. The Nutrient Index values indicated that the micro-watershed was under “medium” category for available nitrogen, phosphorus, potassium and sulphur, whereas, it fell under “low” category with respect to organic carbon. Measures to improve the status of SOC should be taken up in the study area for sustainable production of crop.

GIS-based soil fertility assessment of a micro-watershed of semi-arid tropics in southern India

Available macronutrient status in the soil of Chotanahalli micro-watershed (468 ha) in Kunigal Taluk, Tumkur district was studied with the aid of GIS. Forty three surface soil samples at 320 m grid were collected from Chotanahalli micro-watershed and assessed for the soil organic carbon, available nitrogen, phosphorus, potassium, calcium, magnesium and sulphur. Results revealed that the ranges of SOC, available N, P and K were 2.1 to 7.5 g kg-1, 282.2 to 526.8 kg N ha-1, 8.0 to 67.6 kg P2O5 ha-1 and 124.3 to 338.5 kg K2O ha-1, respectively. Spatial interpolation revealed that majority (321 ha) of the watershed was low in SOC, whereas the whole watershed was medium in available N, P and K. In case of secondary nutrients, available S was found to be medium in majority (423.4 ha) of the area, whereas, exchangeable Ca and Mg were found sufficient in the whole watershed. The Nutrient Index values indicated that the micro-watershed was under “medium” category for available nitrogen, phosphorus, potassium and sulphur, whereas, it fell under “low” category with respect to organic carbon. Measures to improve the status of SOC should be taken up in the study area for sustainable production of crop.

NUTRIENT INDEXING OF OLSEN’S PHOSPHOROUS WITH RELATIONSHIP BETWEEN INORGANIC FORMS OF PHOSPHOROUS IN THE ALLUVIAL SOILS

The phosphorous nutrient index value estimated in the soils along the Yamuna River in Prayagraj falls into the low to medium fertility class. The inorganic forms of phosphorous, namely aluminium bound phosphorous (Al-P), represented 2.15 percent of total-P, resulting in a relatively low proportion, while calcium bound phosphorous (Ca-P), comprised 31.57 percent of total-P. The correlation coefficient (r) between Olsen P and forms of phosphorous saloid P (S-P) was extremely high among all (r = 0.979*) and occluded bound-P (Occl-P) was significantly associated among the inorganic forms (r = 0.767*). This suggests that Occl-P has a significant contribution to the available phosphorous, it is said to be that from the forms of phosphorous Saloid P and Organic P values should be raised and it is recommended that soils with low content of phosphorous are advised to apply organic manures and supplemented by applying of phosphorous fertilizers in the specified crop to increase the levels of P in the soil.

Nutrient Index Approach for Soil Fertility Assessment in Taro (Colocasia esculenta) Farming Areas of Rewa Province, Fiji

Nutrient index methods and fertility indicators can be used to determine the fertility status of soils. The information can be used to develop soil management strategies for farmers. The research was conducted in the Rewa district of Fiji, to assess soil fertility status using the nutrient index approach. Taro (Colocasia esculenta) growing farms were selected from three sub-districts of Rewa province for the present investigation and collected soil samples were analyzed in accordance with standard procedures for evaluating chemical parameters and the status of available nutrients in the soil. The study discovered that the soils of farms are acidic in reaction, have low levels of organic carbon and phosphorus, and are moderate in nitrogen and potassium nutrients, however, the soils had a high content of calcium and magnesium. The nutrient index value (NIV) calculated for organic carbon and nitrogen were recorded as low at 1.60 and 1.43 respectively. The NIV calculated for exchangeable phosphorus, calcium, and magnesium content was recorded as high with 4.46,3.10 and 2.35 respectively. The soil fertility for potassium content was in the medium category with a value of 2.01. The results of this study are expected to help build future research plans for the Rewa taro farms and guide necessary methods for sustainable soil fertility management.

Nutrient Index Approach for Soil Fertility Assessment in Taro (Colocasia esculenta) Farming Areas of Rewa Province, Fiji

Nutrient index methods and fertility indicators can be used to determine the fertility status of soils. The information can be used to develop soil management strategies for farmers. The research was conducted in the Rewa district of Fiji, to assess soil fertility status using the nutrient index approach. Taro (Colocasia esculenta) growing farms were selected from three sub-districts of Rewa province for the present investigation and collected soil samples were analyzed in accordance with standard procedures for evaluating chemical parameters and the status of available nutrients in the soil. The study discovered that the soils of farms are acidic in reaction, have low levels of organic carbon and phosphorus, and are moderate in nitrogen and potassium nutrients, however, the soils had a high content of calcium and magnesium. The nutrient index value (NIV) calculated for organic carbon and nitrogen were recorded as low at 1.60 and 1.43 respectively. The NIV calculated for exchangeable phosphorus, calcium, and magnesium content was recorded as high with 4.46,3.10 and 2.35 respectively. The soil fertility for potassium content was in the medium category with a value of 2.01. The results of this study are expected to help build future research plans for the Rewa taro farms and guide necessary methods for sustainable soil fertility management.

Assessment of Soil Fertility Status of Cuddapah Block in YSR District, Andhra Pradesh, India

A study was conducted to examine the fertility status of soils in Cuddapah block of YSR district, Andhra Pradesh. A total Forty soil samples were collected from ten different villages of Cuddapah block at a depth of 0-15 cm and analyzed for different soil quality parameters viz., soil pH, EC, organic carbon, primary macronutrients (available nitrogen, available phosphorous, available potassium) and secondary macronutrients (calcium, magnesium and available sulphur) by using standard analytical methods in the laboratory. By considering the soil nutrient index values the soil fertility rating as low, medium and high has been given for each fertility parameter. The results revealed that the pH of the soil was found to be neutral to slightly alkaline with a mean value of 7.6. The Electrical conductivity of the soil was free from salinity with a mean value of 0.52 dSm-1. According to the nutrient index values soil samples of Cuddapah block were found to be medium in organic carbon (1.92), low in nitrogen (1.52), low in sulphur (1.00), medium in phosphorous (1.95) and high in potassium content (2.45).

Correlation of Physico-chemical Parameters of Soil and Soil Nutrient Index Status of Kollam District, Kerala, India

The present investigation was carried out at Sam Higginbottom University of Agriculture Technology and Sciences in the department of Soil Science and Agricultural Chemistry lab, India In this study, a total of 27 soil samples were collected from nine different villages on 27 November 2021 in the Kollam district of Kerala, and from each village 3 soil samples were collected and analyzed for their Physico-chemical parameters by using standard laboratory techniques. According to Nutrient Index values, the villages were found to be high in Organic Carbon (2.59), Phosphorus (2.88), Calcium (3), and Magnesium (2.55). The low category was found in Nitrogen (1). The medium category was found in Potassium (1.88). According to the critical limits of soil nutrients the results observed, 100% soil samples were in low range of Nitrogen (N) (64.5 – 181.32 kg ha-1), 92.5% soil samples were in high range of Phosphorous (P) (9.40 – 56 kg ha-1), 89% soil samples were in low to medium range of Potassium (K) (100 – 403 kg ha-1), 100% of soil samples were in the high range of Calcium (Ca) (3.2 – 18 Meq/100g), 78% of soil samples were in high range of Magnesium (Mg) ( 0 – 7.60), 100% of soil samples were in the low range of Sulphur (S) (0.96 – 7.2). The results showed that improvement has to be one for improving soil fertility and quality by practicing improved cropping patterns, decomposition of organic wastes, mulching, and tillage practices.

Geospatial Distribution of Iron in Major Sugarcane Growing Soils of Sivagangai, Tamil Nadu, India

The present study was undertaken to assess the available DTPA iron status in the major sugarcane growing soils of Southern Sivangai district, Tamil Nadu, India. A total of 500 geo referenced surface (0-30 cm) were collected from five blocks viz., Kalaiyarkovil, Padamathur, Sivagangai, Thiruppachetty and Thiruppuvanam and analyzed for basic soil properties and available DTPA iron. Simple correlation was worked out to ascertain the degree of relationship between soil properties and available DTPA iron content of soil study area. The available DTPA iron in the entire sugarcane growing soils ranged from 2.95 to 5.79 mg kg-1, 2.11 to 4.31 mg kg-1, 3.49 to 5.59 mg kg-1, 1.99 to 5.66 mg kg-1 and 3.94 to 6.39 mg kg-1 in soil samples of Kalaiyarkovil, Padamathur, Sivagangai, Thiruppachetty and Thiruppuvanam respectively. In the soil samples from Kalaiyarkovil, Padamathur, Sivagangai, Thiruppachetty, and Thiruppuvanam, the results revealed that 52, 59, 55, 53, and 51 % of the soils were deficient in available iron and 33, 29, 35, 30 and 32 % of the soils were moderate in available iron, and 15, 12, 10,5 and 17 % of the soils were sufficient in available iron. As per the nutrient index study, the soils of study area recorded very low to low fertility rating for available iron and the mean nutrient index value (NIV) ranged from 1.42 to 1.64 in the soil of the study area. SOC and CEC were found to have a beneficial impact on iron availability, whereas EC and CaCO3 levels had a negative impact on DTPA iron availability.

Assessment of Soil Fertility Status Using Nutrient Index Approach in Cassava Farms of Rewa Province, Fiji

Background: Nutrient index methods and fertility indicators can be used to determine the fertility status of soils. The information can be used to develop soil management strategies for farmers. Methods: The research was conducted in the Rewa district of Fiji, with an aim to assess soil fertility status using the nutrient index approach. A total of 57 cassava-growing farms were selected from three sub-districts of Rewa province for the present investigation and collected soil samples were analyzed in accordance with standard procedures for evaluating chemical parameters and the status of available nutrients in the soil. Result: The study discovered that the soils of farms are acidic in reaction, have low levels of organic carbon, low to moderate levels of major primary nutrients, however, the soils had a high content of calcium and magnesium. The soil nutrient index value calculated of soil organic carbon and available phosphorus were recorded as low with 1.48 and 1.40 respectively. The NIV for nitrogen and potassium content was medium category values of 1.91 and 1.95, respectively. The nutrient index value calculated for exchangeable calcium and magnesium content was recorded as high with 2.75 and 2.35 values respectively.