Evaluation of Nutritional Status of Sugarcane Fields in North of Khuzestan Province Using the Compositional Nutrient Diagnosis Method

Sugarcane (Saccharum officinarum L.) is a perennial plant belonging to the cereal family. Sugarcane is a major agricultural crop cultivated extensively in tropical and subtropical regions worldwide. Its phenological growth cycles lead to changes in the plant's nutritional requirements. Understanding these changes requires comprehensive knowledge of the plant's growth stages, as well as the decomposition processes of soil and plant leaves throughout these stages. The availability of nutrients required by the plant during the growth stages of the plant is one of the key points of normal plant growth, therefore, plant nutrition management plays a significant role in achieving optimal performance. Considering these changes, the leaf analysis and diagnosis method can prevent the limitations caused by plant nutritional disorders and the optimal use of fertilizers required in sugarcane cultivation. The combined nutrient detection (CND) method is one of the appropriate methods in interpreting the results of plant nutrient analysis, nutrient requirements and nutritional balance status in plants. Performing leaf sample analysis is an effective approach to monitor and assess the nutritional status of sugarcane. Given that sugarcane may have a multi-year cycle, this method provides a reliable indicator for assessing the nutritional needs of the crop during its cultivation period. One of the effective methods for assessing nutritional limitations in sugarcane is through the CND method. This method provides the advantage of quickly delivering up-to-date standards while identifying specific nutrients responsible for nutritional imbalances that may reduce productivity. Additionally, it enables the detection of limitations caused by deficiencies and excesses, indicated by negative and positive indices, respectively. The aim of this study was to determine the order of limitation for nitrogen, phosphorus, potassium, calcium, magnesium, copper, iron, manganese, and zinc using the CND in the commercial sugarcane variety CP69-1062 grown in ratoon farms. In the northern Khuzestan farms, which have the potential for higher sugarcane production, nutritional limitations may still restrict productivity.

The present study was conducted in ratoon sugarcane fields in the Shuaibih area of Imam Khomeini sugarcane cultivation and industry. The objective of this study was to examine the impact of fertilization management and assess nutrient balance in the commercial sugarcane variety CP69-1062 grown in ratoon farms. To achieve this, 25 farms were selected during the 2023-2024 crop year. The concentrations of nitrogen, phosphorus, potassium, calcium, magnesium, iron, manganese, zinc, and copper were analyzed in the leaves of the sugarcane plants. After the harvest season, the yield of each field was measured and recorded. The intermediate yield, obtained using the Khayari method, allowed the farms to be divided into two groups based on whether the yield was favorable or unfavorable. Subsequently, CND reference numbers, CND nutrient index and nutrient balance index (r²) were calculated. This index was calculated using the Keith-Nielson method, based on the Chi-square statistical distribution function (K²) in Excel software.

The results of the cumulative distribution function of the variance of nutrients, with an intermediate yield of 99 tons per hectare, indicate that 52% of the studied ratoon sugarcane farms were in the high yield group and 48% were in the low yield group. After solving the equations of the cumulative function of the third order of the studied nutrients, the nutrient balance index values were found to fall within the range of (2.62 to 20.58) in the optimal performance group, with an average value of 109.28 tons per hectare. The highest value of this index (r2 = 199.95) was observed in the Raton sugarcane field, with a yield of 73.08 tons per hectare. The CND reference numbers of the evaluated nutrients and remaining compounds were as follows: V*N= 2.87, V*P= 1.04, V*K= 2.64, V*Ca =1.95, V*Mg =1.29, V*Fe = -1.75, V*Mn = -3.35, V*Zn = -4.72, V*Cu = -3. 92, and V*Rd = 4.13. The index of CND nutrients showed that copper and iron had the highest negative index among micronutrients in the group of low-yielding ratoon sugarcane fields. The presence of calcareous conditions in the soil of the studied fields can be one of the reasons for this observation.

The CND nutrient balance index (r2) was positive, especially in low-yielding ratoon sugarcane fields, and much higher than its value in high-yielding fields, which indicates nutritional imbalance in these fields. Proper management and balanced use of fertilizers should be considered. It can improve yield and growth cycle of sugarcane.