نشریه پژوهشهای خاک (علوم خاک و آب)
سال سی و ششم شماره 1 (بهار 1401)

To study the imbalanced fertilization and to optimize fertilizer use in canola farms in the north of Khuzestan Province, Iran, we used Compositional Nutrient Diagnosis (CND) and Deviation from Optimum Percentage (DOP) methods. This research covered 30 canola (Brassica Napus) fields during one cropping season (2019) and soil, leaf, and water samples were collected and analyzed, and grain yield was also measured. Nutritional elements including N, P, K, Fe, Cu, Zn and leaf Mn were determined by standard laboratory methods. Yield community were divided into low and high yield groups using the cumulative function of nutrient variance ratio and K-square distribution function considering the intermediate yield of 2882 kg. ha-1. Then, according to the CND system method, the standard norms for N, P, K, Fe, Cu, Zn, Mn and residual elements (Rd) were determined as 3.27± 0.14, 0.83± 0.17, 2.73± 0.2, -1.89± 0.13, -4.23± 0.53, -3.45± 0.3, -3.46± 0.26, and 3.27± 0.14, respectively. The results of CND system method showed that the most limiting factors in yield were K (among macro- elements) and Mn (among micro- elements). In DOP method, the optimum levels of N, P and K were 5.27%, 0.44%, 2.72%, and for Fe, Cu, Zn, and Mn were 313, 37, 77, and 67 mg. kg-1 dry weight, respectively. In this method, the order of nutrient deficiency was revealed as Cu> Zn> Mn> N> Fe> P.

In order to evaluate the effect of integrated soil fertility management (ISFM) on growth and nutritional balance of Thompson Seedless grape (Vitis vinifera L.), an experiment was conducted in a randomized complete block design including four treatments with three replications in five private vineyards located at Urmia, Iran, during 2020 and 2021seasons. Treatments included T1= check (no fertilization), T2= farmers’ conventional fertilization, T3=optimum fertilization of mineral nutrients and T4 integrated soil fertility management. Results indicated no significant difference among the study sites in terms of cluster weight, chlorophyll index, titratable acidity (TA) and total soluble solids (TSS) of fruits, but a significant difference was observed between macro- and micronutrients, except for iron (Fe). The cluster weight was increased in all fertilized treatments compared to the check (p≤0.05). Grapes increase in T3 and T4 compared to T2 was 2.27 and 4.04 kg/vine, respectively. A similar trend was observed in relation to the leaf chlorophyll index, which increased in T4 by 10.99% and 9.69%, respectively, compared to T2 and T3. TA and TSS concentration accumulation in berries were affected by T3 and T4 treatments. TA showed a significant decrease in T4 compared to T1 by 16.09% (p≤0.05). However, TSS accumulation showed the highest value in the T4 (p≤0.05). There was no significant difference between T3 and T4 in terms of these two qualitative Characteristics. Evaluation of nutritional status using compositional nutrient diagnosis (CND (norms in control treatments indicated that, on average, the order of nutritional requirements of macro- and micronutrients were K=Ca>Mg>N>P and Fe>Zn>Mn>Cu>B, respectively. The lowest nutrient balance index (9.02) was obtained in the T4 and the highest value was observed in T1 treatment (35.02). In general, it is concluded that due to the significant increase in quantitative and qualitative factors of grape yield with ISFM, this technology was the best for balanced fertilization program and optimum fruit production in vineyards.

Tomato is one of the most important crops in Bushehr Province and its out-of-season cultivation has doubled its importance. Achieving optimal performance is possible by balancing the nutrients. Nutritional indicators are used to diagnose nutritional disorders and the subsequent optimal use of chemical fertilizers. This research was conducted by selecting 79 tomato farms from different parts of the province with different yields in two years (2018-2020). Soil samples of selected fields were taken from a depth of 0 to 30 cm and leaf samples were taken at the beginning of fruiting. The average yield of each field was measured at the end of harvest and laboratory analysis of samples was performed by standard methods. The experimental data were fitted with compositional nutrient diagnosis model (CND). The studied farms were divided into two groups, low and high yields, with a cut-off yield of 86.7 tons per hectare, based on the highest yield and calculations according to the CND method. Reference numbers of leaf nutrient concentrations were calculated as 2.79±0.202, 0.460±0.174, 2.62±0.143, 2.57±0.195, 2.08±0.225, -2.20±0.134, -3.10±0.134, -3.74±0.200, -4.34±0.250, and -3.25±0.173 for N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, and B, respectively. Also, the optimal leaf nutrient concentrations range for 86.7 tons per hectare of yield were N: 3.38±0.94, P: 0.324±0.074, K: 2.77±0.397, Ca: 2.63±0.423, Mg: 1.64±0.394 percent, and for Fe: 221±24.6, Mn: 90.9±14.8, Zn: 48.3±11.1, Cu: 27.3±8.40, and B: 79.3±17.5 mg.kg-1. Potassium, N, and Zn deficiency as well as excess amount of Mg, Ca, and Mn were identified as the imbalanced nutrients in tomato production in Bushehr Province. This can be due to the calcareous nature of the soil and unbalanced use of chemical fertilizers.

In Mazandaran Province, use of Carrizo citrange (Citrus sinensis Osb. × Poncirus trifoliata L. Raf.) as an alternative rootstock for citrus is expanding. Also, due to great changes in lime content  of the soils (0- 45%) and soil texture, it is necessary to study the response of this rootstock to the soils conditions. Therefore, the present study aimed to evaluate the growth trend and tolerance of this rootstock to calcareous soils of East Mazandaran. To this end, an experiment was conducted for two years in a randomized complete block design in seven soils with different textures (sandy to clay loam) and calcium carbonate content (2- 45%). Measurements included vegetative growth trend, dry weight, chlorosis rate, fluorescence index (Fv/Fm), and nutrient concentration in leaves and roots. The results showed that the highest dry weight of aerial parts was obtained from soils with loam texture and total lime of 2% and soils with loamy sand texture and total lime of 40%. The highest chlorosis rate was obtained from soils with loam texture and 45% lime with 16% active lime and the lowest chlorosis rate was obtained from active- lime-free soils and 2% total lime. The average of Fe concentration in the roots was about 8.94 times the average concentration in the leaves, indicating accumulation and deposition of iron in the roots. In most soils, the amount of manganese available for citrus trees was excessive, but the mean concentration of leaf was less than adequate. The overall mean Mn concentration in the roots was about 6.67 times more than its mean concentration in leaf. The most limiting element for Carrizo citrange rootstock and scion was Mn and its low transfer efficiency from root to leaf. The results of mean chlorophyll content and chlorophyll fluorescence index (Fv / Fm) of leaves showed that soils with loam texture and low total lime and soils with light texture and high total lime had the highest amount of chlorophyll and fluorescence index. According to the results, soil texture influenced tolerance of Carrizo citrange rootstock in calcareous soils and, in relatively medium and heavy texture soils, the use of this rootstock in soils with total lime less than 14% is recommended, but in light-textured soils, its use in soils with total lime about 40% is also recommended. Therefore, in choosing this rootstock, it is recommended to consider soil texture and lime content.

In order to evaluate the effect of nitrogen rates and application times on yield and some quality characteristics of strawberry cultivar Queen Elisa in the perennial harvesting system, a field experiment was conducted at Grizeh Station in Sanandaj District, Iran, from September 2011 to 2013. Treatments included four rates of nitrogen (N0, N50, N100, and N150 kg N. ha-1 from urea) and four application times: T1=Total nitrogen in spring (two weeks before flowering), T2=Total nitrogen in spring (one day after the last harvest), T3=Total nitrogen at the beginning of September, and T4=Application of nitrogen in three equal installments at times T1, T2, and T3. Experiment was conducted with three replications as a factorial in a randomized complete block design. The results of analysis of variance showed that the effect of year on yield, TSS, pH, acidity, and dry matter of fruit was significant (p<1%). The main effects of nitrogen rates and application time on yield, dry matter, and TSS of fruit were significant (p<1%). The interaction effect of year and application time on fruit yield was significant (p<1%). The interaction effect of application time and nitrogen rates on fruit yield was significant (p< 5%) and on dry matter and TSS of fruit at p<1%. The highest fruit yield was obtained in N150 treatment and T4 application time of 629 g. plant-1 followed by fruit yield in N150 T3, N100 T4, and N100 T3, respectively, while N150 and N100 at T2 were not significantly different from the control. The effects of different nitrogen rates and application times of nitrogen on chlorophyll index and leaf nitrogen concentration were significant (p<1%). With increasing nitrogen rates, its concentration in the leaves increased. There was a strong positive correlation between nitrogen concentration in leaves and leaf chlorophyll index. Nitrogen rates and application times had no effect on titratable acidity and pH of fruit. By application of 100 kg N.ha-1 in three equal installments at T4, the highest yield, TSS, and fruit dry matter were obtained.

Considering that most of the calcareous soils of Iran are deficient in one or more micronutrients, optimal nutrition of nutrients such as silicon under the influence of biological treatments can be highly effective in these conditions. Therefore, this study was conducted to investigate the effects of silicon and phosphate-soluble bacteria on the availability of micronutrients for wheat. We used a completely randomized design in three replications and treatments included 0, 150, 300, 600 mg/kg silicon from a source of silicic acid and three levels of bacteria (non-inoculation of bacteria, Bacillus and Pseudomonas). The study was conducted in the greenhouse of Soil and Water Research Institute. The results showed that the combined use of silicon and phosphate-solubilizing bacteria increased the uptake of manganese and iron compared to the control treatment. However, the antagonistic effect between nutrients reduced zinc uptake at higher levels of functional silicon. The effect of inoculation with Bacillus and Pseudomonas on the amount of zinc, manganese and iron uptake by wheat was superior to the control bacterium. On the other hand, application of silicon (600 mg silicon/kg soil with Pseudomonas bacteria) significantly increased the concentration of phosphorus in wheat to the optimum level. Since excessive use of phosphate fertilizer in calcareous soil reduces absorption of micro nutrients, the combined use of silicic acid and phosphate-soluble bacteria can be recommended as an effective method for increasing availability of micro nutrients in greenhouse conditions.

Leaching and ammonia volatilization are known as the main pathways of nitrogen loss as well as the cause of low nitrogen use efficiency. The present study aimed to study the interaction of five nitrogen fertilizer sources (ammonium sulfate, ammonium nitrate, urea, sulfur coated urea and potassium nitrate) and three soil salinity levels (ECe = 2, 8, and 12 dS/m) on daily as well as cumulative ammonia volatilization. The results showed that salinity and nitrogen fertilizer sources had significant effect on cumulative and daily ammonia volatilization rate. At soil salinity of 2 dS/m, nearly 51%, 44%, 45%, 6% and 0.01% of ammonium sulfate, ammonium nitrate, urea, sulfur coated urea, and potassium nitrate were lost through ammonia volatilization, respectively. These values at soil salinity level of 12 dS/m significantly increased to 73.7%, 54%, 57%, 8%, and 0.01% for ammonium sulfate, ammonium nitrate, urea, sulfur coated urea and potassium nitrate, respectively. In general, the results showed that potassium nitrate had the minimum ammonia loss through volatilization and was followed by sulfur coated urea, urea, ammonium nitrate, and ammonium sulfate, respectively. Regarding the highest nitrogen uptake efficiency and minimum nitrogen loss, potassium nitrate is recommended as the most efficient source of nitrogen fertilizer.