Iranian Journal of Soil Research
Year:2009 | Volume:23 | Issue:1|Papers Count:15

In order to investigate two durum wheat cultivars response to splitting and foliar application of nitrogen, an experiment was conducted during 2002-04 growth seasons. The experiment was laid out in a Randomized Complete Block Design adopting split-factorial arrangement as follows: factor a: variety (Aria and Dena durum wheat varieties), factor b: Nitrogen application (2, 3, and 4 splits), factor c: foliar application of nitrogen at 3% concentration (one time at anthesis). Combined analysis of data revealed that Aria and Dena cultivars were significantly different in grain yield as well as 1000 grain weight, protein percentage, number of grain per spike, and yellow berry characteristics. Dena had higher grain weight and yield as well as protein yield compared with Aria. However, Aria cultivar showed higher protein content. Split application of nitrogen significantly affected grain weight and hardiness as well as yellow berry. Four times split application of nitrogen at sowing, stem elongation, pollination, anthesis, and grain filling stages had the highest effect on grain quality. One time foliar application at anthesis stage increased grain yield significantly as well as protein yield but decreased yellow berry. Foliar application of nitrogen with 3% concentration at anthesis significantly increased grain quality and quantity, therefore, this treatment is recommended. Most significant and positive effect of foliar nitrogen application was observed on yellow berry percentage reduction.

Information about phosphorus fractions is important for evaluation of their status in soil and understanding of soil chemistry that influence soil fertility. To obtain such information, amount and distribution of P in different fractions of 20 soil samples of Qazvin province, Iran were determined by sequential extraction methods and their relationships with each other and with soil characteristics were investigated. Total P ranged from 700 to 1040 mg kg-1. The clay ranged from 18-52%, CEC from 14.5-33.5 c mol(c) kg-1 and the active CaCO3 from 2.9-19.4%. The amount of different P forms i.e. dicalcium phosphates (Ca2-P), octacalcium phosphates (Ca8-P), Al-phosphates (Al-P), Fe- phosphates (Fe-P), occluded-P (O-P), and P as apatite (Ca10-P) were found to range from; 1.6-42.3, 72-314, 14.5-54.8, 8.4-34.8, 5.9-33.4 and 262-697 mg kg-1, respectively. Simple correlation coefficients showed that Olsen-P had a significant correlation with soluble-P, Ca2-P, Fe-P and O-P. A significant correlation was also observed among different forms of P, which presumably reflects the existence of a dynamic relation between the chemical forms of an element in soil. Clay with Fe-P and O-P; total P with Ca8-P, Al-P and Ca10-P; and CEC with Al-P and O-P had positive and significant correlations. However, a significantly negative correlation was found for electrical conductivity (EC) with Ca8-P and Al-P; organic carbon (OC) with Ca10-P, and active CaCO3 with Ca10-P.

This experiment was conducted to assess the effects of different NH4+/NO3- ratios and calcium levels on growth, nutrients concentration and quality of rose flower (Rosa hybrida L.). Statistical design was factorial in a randomized complete block with four replications. Rose plants cultivar Vandentta were grown with three NH4+/NO3- ratios (0/100, 25/75 and 50/50) in combination with two levels of calcium (1.6 and 4.8 mM) under hydroponic conditions. The results revealed that, except for leaf chlorophyll content index, none of the vegetative growth indices were affected by NH4+/NO3- ratios and calcium levels in the nutrient solution. Application of ammonium in the nutrient solution resulted in increasing N, P and micronutrients and decreasing Ca and Mg in different parts of rose flower, respectively. Also, N, P, Fe, Cu and B in the different parts of rose flower were not affected by increasing the Ca concentration in the nutrient solution. However, application of Ca resulted in increasing Ca and decreasing K, Mg, Mn and Zn in the different rose parts, respectively. At the two flower harvesting dates, yield increased significantly by application of NH4+. Also there was no difference between NH4+/NO3- ratios of 25/75 and 50/50 in the yield. However, rose quality indices during post harvest were affected significantly (P£0.01) by the previous application of ammonium and calcium. Increasing NH4+/NO3- ratio up to 50/50 significantly reduced the weight of flowering stem at the end of vase life, as well as the flower diameter and also vase life; whereas, calcium application up to 4.8 mM significantly increased all these quality indices. On the basis of this experiment, in view of the economic and flower quality indices, the application of 25 percent of nitrogen as NH4+ and increasing level of calcium in the nutrient solution up to 4.8 mM are recommended for cut rose production in hydroponic conditions.

Pistachio is one of the most important strategic and exportable crops in Iran; therefore, identification of the factors affecting its growth is necessary for its sustainable production. The objectives of this investigation were to identify the major soils under pistachio and to evaluate the effects of their characteristics on the growth, yield and splitting of pistachio. Anar region, located in 75 km northwest of Rafsanjan, was selected for this study in 2006. Gardens with the same management practices, pistachio cultivar, water quality, and irrigation interval that contained trees varying in growth status were sought. Finally, six gardens were chosen and each garden was divided into two parts: desirable and undesirable growth. In each part, three replicates and in each replicate three trees were selected. Soil sampling was done for 0-40 and 40-80 cm depths to analyze selected soil physical and chemical properties. Yield, fruit splitting, perimeter of trunk, length of shade cover and height of the trees were also determined for each replicate. In each part of the gardens, one soil profile was studied to determine soil classification up to the family level. Results showed that high salinity and clay content decrease pistachio yield significantly. Clay content had also showed a negative significant correlation with fruit splitting, diameter of trunk, length of shade cover and height of the trees. Therefore, preparation of soil salinity and texture maps are recommended for proper pistachio management. Results indicate that soil consistency in dry state of the parts with "undesirable" growth was harder than that of the parts with desirable growth. Also, soil classification information at the family level could not be used reasonably to distinguish the effects of different soil types on pistachio yield.

In order to study the effect of Iranian natural zeolite application on reducing nitrogen leaching in light soils, a field experiment was carried out during 2006-07 in the research farm of Tarbiat Modares University Iran. A factorial experiment was used based on RCBD with 3 replications., The variables included rates of zeolite (0, 3, 6 and 9 t.ha-1) and nitrogen rates (90, 180 and 270 kg ha-1) in the form of urea. Winter canola (Brassica napus L. Cv. Okapi) was sown in October 2nd and for assessment of forage production of the plant, aboveground biomass of canola was harvested in the early pod formation stage. Amount of nitrogen leaching was calculated by measuring NO3- and NH4+ concentration in drainage water under root extension zone of canola multiplied by the total amount of deep percolation. The result showed that effect of nitrogen and zeolite on forage yield of canola and prevention of nitrogen leaching were significant (p£0.01), but interaction effect of the two factors was not statistically significant. Application of zeolite in rates of 6 and 9 ton ha-1 caused significant decrease in NO3- concentration in leachate sample, but different levels of zeolite had no significant effect on decreasing NH4+ leaching. Increased application of zeolite from 3 t ha-1 to 9 t ha-1 diminished concentration of nitrogen in the plants. The highest fresh and dry forage yields were, respectively, 70.66 and 11.33 t.ha-1 and were obtained from 270 kg N ha-1. Increasing N rates from 90 to 270 kg ha-1 increased nitrogen content of plant and amount of leaf chlorophyll by as much as 6% and 15%, respectively. According to our findings, application of natural zeolites indirectly increased yield and prevented nitrogen leaching from soils. Further research is needed to understand probable role of zeolite in prevention of nitrogen leaching.

The conventional tillage disturbs aggregates, specially, in loamy and sandy loam soils and increases the susceptibility of soil to water and wind erosion. Thus, use of other tillage methods, especially in rain fed agriculture, is recommended. The objectives of this study were to investigate the impacts of different tillage methods on soil organic matter, soil aggregate stability, and linear development of gullies. The treatments included conventional tillage (preparation of seed bed by a disc plow), conservation tillage (sowing with Combinator device without any soil plowing while conserving 100% of the residues on soil surface), minimum tillage (sowing with Combinator device without any soil plowing while conserving about 30% of the residues on the soil surface), and control (without sowing and tillage). Treatments were arranged as randomized complete block design (RCBD) with three replications at the head cuts of the existing gullies in a rain fed wheat farm. The results showed that minimum and conservation tillage significantly increased soil organic matter and water aggregate stability compared to the conventional tillage. In addition, the three mentioned treatments decreased the linear development of gullies significantly as compared to the control. Results, suggest that gully development may be mitigated by using conservation or minimum tillage.

Bone meal contains a large amount of phosphorus that could almost supply the phosphorus needs of crops. The main objective of this study was to determine the capability of bone meal for releasing phosphorus and its effect on growing corn. An experiment was conducted in a completely randomized design with three replications under laboratory and greenhouse conditions with 6 treatments including 400 and 800kg.ha-1 ordinary bone meal, 400 and 800kg.ha-1 acidulated bone meal, 200kg.ha-1 triple super phosphate, and control. The results demonstrated that in treatments with ordinary bone meal, phosphorus release had 30 days lag compared with triple super phosphate. Acidulation of bone meal caused faster and more release of phosphorus. The experiment also revealed that acidulated bone meal did not change the concentration of phosphorus in the shoot. However, shoot dry matter weight and phosphorus uptake by corn were significantly higher in acidulated vs ordinary bone meal. But, compared to the chemical fertilizer, their differences were not statistically significant.

Application of soil and water conservation techniques at watershed areas not only reduces soil erosion from watershed areas and sediment accumulation in the dam basins, but also improves rangelands and can recharge the aquifers. Improper estimation of the parameters corresponding to the mechanical soil and water conservation structures such as capacity, distance apart, number and distribution of these structures, may lead to loss of time and capital. In this paper a new model is introduced to predict runoff hydrograph and sediment sedigraph generated from a storm more accurately. The model used for runoff and erosion prediction at watershed areas is European Soil Erosion and Runoff Model, EUROSEM. This model is a physical distributed single event model derived to be used in small hydrological watershed areas. It is able to take spatial and temporal variations of rainfall, catchments and vegetation cover characteristics and process them in three input files and, finally, give out the results in three output files. The model was calibrated and validated using the data measured in the field for both protected and unprotected plots. The results showed that it could simulate all parameters for both cases successfully. Thus, proper selection of input parameters enables the model to predict surface runoff for design and management of soil and water mechanical structures at watersheds.

Salinity stress in some arid and semi-arid areas is of great importance due to its potential negative impact on crop yield. Under salinity stress the amount of 1-aminocyclopropane-1-carboxylate (ACC), a precursor for ethylene in plant, increases. Hence, a research work was planned hypothesizing that ACC deaminase producing Pseudomonas fluorescens and putida may alleviate the harmful effects of salinity on canola (Brassica napus L.) growth. The experiments were conducted in the Soil and Water Research Institute, Tehran, Iran. Seven stages of experiments were conducted to isolate and characterize ACC Deaminase producing P. fluorescens species and to determine factors, enhancing their growth and, hence, their effects on the germination of canola seeds. Under salinity stress, in 14% of the isolates, ACC deaminase activity was observed, indicating that they are able of utilizing ACC as the sole source of N. Bacterial species differed in their ability to synthesize auxin like compounds, hydrogen cyanide and ACC deaminase. Under salinity stress the rate of germinated seeds, inoculated with the species of ACC Deaminase producing P. fluorescens and putida, was significantly higher. Hence, inoculation of canola seeds with P.fluorescens and putida may alleviate the stress of salinity on canola seed germination and, perhaps, canola growth.

Improper application of phosphorus chemical fertilizers does not increase crop yield. Indeed, it may cause various problems in absorption of microelements by plants, specially in calcareous soils. The present study was conducted to evaluate use of azotobacter and mycorrhiza as bio-fertilizer and phosphorus (super phosphate) as chemical fertilizer on corn crop (var. KSC 704). The effects of three factors including Azotobacter chroococcum (inoculated and not inoculated), Glomus intraradices (inoculated and not inoculated) and phosphorus (0, 50, 100, and 200 kg/ha) was evaluated in a factorial experiment using completely randomized block design with three replications. The effects of the three factors and their interactions were investigated on some parameters such as root colonization, dry matter, Zn, Fe, Cu, Mn and P concentration in shoot tissues. The results showed that mycorrhizal symbiosis increased dry matter (4.9 %), with accompanying significant decrease in Cu (14.9 %) and Mn (9 %) and increase in P (28.8 %) in shoot tissues concentration. Application of azotobacter improved the metabolites that were effective in increasing growth of plant tissues and dry matter (7.5 %), but led to significant decrease in Fe concentration (about 6.7 %). Different levels of phosphorous significantly increased P (25.6 %) in shoot tissues while decreasing concentration of Cu (22.2 %), Fe (21.4 %), Zn (15.8 %), and root colonization (about 16.6 %). The interaction between mycorrhiza and azotobacter also increased root colonization (43.3 %), dry matter (12 %) and P concentration (48.8 %), but decreased Fe (11.8 %) and Cu (15.6 %) concentration significantly (P<0.05 %) with no effect on Zn and Mn. The triple interaction of mycorrhiza, azotobacter, and phosphorus was not evident.

This experiment was conducted to investigate the effect of water stress at different growing stages of cowpea. A complete randomized block design with five treatments in four replications was used on a silty clay loam soil under furrow irrigation. The treatments consisted of one control (without water stress) and four treatments with water stress at, respectively, vegetative, flowering, pod forming, and pod filling stages. Soil moisture was measured weekly by neutron meter before each irrigation. Evapotranspiration was calculated using water balance method. The water requirement was supplied based on difference between soil moisture and field capacity. Seed yields in the control and stress treatment at vegetative stage were, respectively, 2384 and 2170 kg.ha-1, without significant difference. The amounts of water supply were, respectively, 946 and 828 mm. Seed yields of the treatments with water stress at flowering, pod forming, and pod filing stages were 1782, 1760, and 1700 kg.ha-1, respectively, being  significantly lower than the first two treatments. The amounts of water supplied to these three treatments were 820, 898, and 789 mm, respectively. According to the results, cowpea tolerates water stress for two weeks at vegetative stage, but, the same water stress experienced at flowering, pod forming or pod filling stages decreases the number of seeds per pod, the average weight of one seed, and total seed yield. Relations found between the seed yield with the amount of water supply and seed yield with evapotranspiration are presented in the main text.