Soil science
A. Zeinadini; M.N. Navidi; A. Asadi Kangarshahi; M. Eskandari; S.A. Seyed jalali; A. Salmanpour; J. Seyedmohammadi; M. Ghasemi; S.A. Ghaffarinejad; Gh. Zareian
Abstract
Introduction: Iran is one of the most important countries in citrus (oranges) production. Citrus fruits are grown in different soils with a wide range of physical, chemical and fertility properties in the country, although some restrictions in the cultivated lands cause yield loss. In this regard, the ...
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Introduction: Iran is one of the most important countries in citrus (oranges) production. Citrus fruits are grown in different soils with a wide range of physical, chemical and fertility properties in the country, although some restrictions in the cultivated lands cause yield loss. In this regard, the present study was conducted to investigate the effect of physical, chemical and soil fertility characteristics on citrus yield in important areas under cultivation, the regression relationships of characteristics with yield, and the rating of soil and land parameters. Materials and Methods: The 138 oranges orchards (118 orchards for rating and 20 orchards for validation) were selected in Fars, Mazanderan, Kerman and Guilan provinces. In each garden, a questionnaire was completed, a soil pedon was studied and soil samples were taken to carry out the appropriate physicochemical analyses. The selected soil and land characteristics were soil salinity (EC), exchangeable sodium percentage (ESP), pH, gypsum content, soil calcium carbonate (TNV), organic carbon (OC), clay, sand, silt, gravel, and soil available phosphorus and potassium contents. From the whole obtained data, 20 data were considered for validation purpose and the remaining data were used for modeling based on stepwise multivariate and simple regression methods. In these equations, the relationship between yield, as dependent variable, with soil and land characteristics, as independent variables, was investigated. Finally, land characteristics rating was obtained by the FAO method and the proposed crop requirements table was evaluated using the validation dataset. Results and Discussion: The results of descriptive statistics analysis showed that the variance values for available potassium, sand, clay, gravel and TNV were high and for pH and OC and gypsum were negligible. Therefore, most soil properties have a wide range of variation which could be related to the fact that oranges are grown in a wide range of soil types. The value of TNV varied between 10 and 33.3%. The presence of carbonate in soil reduces the availability of macro- and micronutrient elements in direct and indirect manners. The average of EC in the studied orchards was 5.4 dS.m-1. Minimum, maximum and average of ESP were 1.7, 28 and 10.7, respectively. The lowest and highest salinity and sodicity were observed in Mazandaran and Kerman soils, respectively. Maximum, minimum and average percentage of gypsum were 12, 0.36 and 3.54%, respectively. The highest amount of gypsum was observed in Bam and Shahdad regions of Kerman province and the lowest gypsum content was observed in Mazandaran and Guilan provinces. The soil pH varied from 6.63 to 8.8 with the average of 7.8. The soil OC values were between 0.05 and 3.53% and its average was 0.89%, showing the fact that the most studied soils were poor in organic matters. The average of soil available phosphorus and potassium in the studied orchards for citrus was less than the critical level. The average, minimum and maximum of available potassium were 224, 100 and 360 mg.kg-1, respectively. The mean, minimum and maximum amounts of available phosphorus were 21.6, 8 and 45.9 mg.kg-1, respectively. According to the multivariate regression model, among soil properties, EC, ESP, TNV, gypsum, gravel, available phosphorus and potassium were selected by the model. The determination coefficient of the model was 0.95, indicating that these properties have the greatest effect on citrus yield. Simple regression equations demonstrated that TNV, gypsum, EC, ESP, sand, clay, gravel, available potassium and phosphorous had the highest correlation (R2 > 0.6); and soil OC and pH had the lowest correlation (R2<0.2) with yield. The equations also revealed that soil EC, ESP, gypsum, TNV and gravel percentage had the greatest effect in yield loss, and soil organic carbon, absorbed phosphorus and potassium had the greatest effect on increasing citrus yield. As stated in equations, reported permissible and critical thresholds for effective soil properties on citrus yield, were 2.4 dS.m-1 for EC, 5 for ESP, 1.5% for gypsum, 20% for TNV, 22 mg.kg-1 for available phosphorus, 280 mg.kg-1 for available potassium, 110 cm for soil depth, and >2 m for groundwater level. Finally, evaluating the proposed crop requirements table with validation dataset fitted between citrus yield and soil index, resulted in the determination coefficient value of 0.79, denoting the acceptable accuracy of proposed table. Conclusion: Overall results showed that the main land limiting characteristics for orange production were soil salinity and sodicity, high amount of soil calcium carbonate and gypsum. Among unsuitable physical and fertility properties of soil, salinity and sodicity are the most effective factors affecting yield reduction. Consequently, proper management practices such as introducing cultivars compatible with these soil conditions, soil remediation and leaching operations to reduce soil salinity and sodicity are necessary. Furthermore, in most areas under orange cultivation such as Fars and Kerman provinces, the soil calcium carbonate content is more than the critical level for plant growth. In addition, the averages of soil available phosphorus and potassium were less than the critical levels, which should be considered for nutrient management of orchards. The proposed table of crop requirements seems to be accurate enough to conduct land suitability studies for orange varieties, especially cultivars grown in the north and south of the country.
Salman Mirzaee; MirHassan Rasouli-Sadaghiani; Naser Miran
Abstract
Introduction: Citrus is an important fruit crop cultivated in tropical regions of the world with immense nutritional value and advised on daily basis in diet. In Iran, it is cultivated in high reaches of northern and southern regions. The low productivity has been ascribed mainly to the nutritional health ...
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Introduction: Citrus is an important fruit crop cultivated in tropical regions of the world with immense nutritional value and advised on daily basis in diet. In Iran, it is cultivated in high reaches of northern and southern regions. The low productivity has been ascribed mainly to the nutritional health of the plantations which is the most concern among farmers. To plan fertilization efficiently, it is necessary to know the desirable concentration of macro and micro nutrient in tissues that are representative of the plant’s nutritional status. Traditionally, to determine the optimum fertilizer doses the most appropriate method was to apply fertilizer on the basis of soil test and crop response studies (Regar and Singh, 2014) which defied the synergistic and antagonistic effects in relative availability of different essential nutrients from soil. The foliar nutrient concentration is considered most pertinent and reliable method to judge the well-being of a tree as it represents the in situ condition in a holistic way and is a very powerful tool for nutritional diagnosis to assess deficiency symptoms and make fertilizer recommendations (Filho, 2004). Because of the dynamic nature of the leaf tissue composition, strongly influenced by leaf age, maturation stage, and the interactions involving nutrient absorption and translocation, the tissue diagnosis may be a practice of difficult understanding and utilization (Walworth and Sumner, 1987). The Diagnosis and Recommendation Integrated System (DRIS) developed by Beaufils (1973), expresses the result of foliar analysis through indices, which represent in a continuous numeric scale, the effect of each nutrient in the nutritional balance of plant. DRIS is advantageous as it presents continuous scale and easy interpretation; allows nutrient classification (from the most deficient up to the most excessive); can detect cases of yield limiting due to nutrient imbalance, even when none of the nutrient is below the critical level; and finally, allows to diagnose the plant nutritional balance through an imbalance index (Baldock and Schulte, 1996). Nutritional balance is an important factor in increasing the yield and improving the quality of horticultural products especially Citrus. Hence, the objective of this study was to determining the optimum level of the macro and micro nutrient elements and evaluating the nutritional status of Lisbon lemon and Perl tangerine in Dezful.
Materials and Methods: For this purpose, 30 Lisbon lemon and 30 Perl tangerine gardens were selected randomly from citrus gardens in Dezful. Leaf samples were collected from middle of terminal shoots of current year growth in the periphery of tree from in late September. Leaf samples were washed in detergent followed by tap water and distilled water. Leaves dried under shade and then dried in hot air oven at 70ºC for 48 hours. The dried leaves were grounded to fine powder by using mixer and stored in air tight butter paper bags for nutrient analysis. Kjeldahl method was followed to measure total nitrogen, and phosphorus was measured by vanado-molybdophosphoric yellow colour method using spectronic, while potassium was measured by flame photometric method. Other elements content was determined by atomic absorption system. The gardens were divided into two groups of low and high yielding. All forms expression and their variance into two groups and variance ratio the group of low to high yielding in tow type gardens were calculated. Then using DRIS calibration formula, DRIS index for nutrient elements with low yielding were determined and nutrient balance index (NBI) were calculated.
Results and Discussion: The results showed that the optimum level in Lisbon lemon leaves were 2.97, 0.11, 1.85, 3.88 and 0.17% for N, P, K, Ca, Mg and 200.5, 24.9, 23.9, 68.8, 32.9 mg.kg-1 for Fe, Zn, Mn, Cu and B, respectively. In addition, the optimum level in Perl tangerine leaves were 2.97, 0.09, 1.57, 3.44 and 0.34% for N, P, K, Ca, Mg and 167.2, 32.7, 26.1, 28.0, 48.4 mg.kg-1 for Fe, Zn,Mn, Cu and B, respectively.
Conclusion: In general, based on DRIS indices priority on the macro and micro nutrients as Fe > N > B > K >Mn> Ca > Mg = P > Cu > Zn for Lisbon lemon and B > Fe > K > Cu > N > Ca > Mg >Mn> Zn > P for Perl tangerine were determined. The NBI of all gardens with low yielding was more than zero, indicating an imbalance nutritional in low yielding gardens.
