Agricultural Sciences and Technology
Year:2007 | Volume:21 | Issue:1 (SPECIAL ISSUE IN WATER & SOIL)|Papers Count:16

Land use type has been an important part of human societies. As it gradually develops, and the human society demands change, the necessity of changing the land use is becoming more obvious.The objective of this study was to determine the qualitative land capability of Mashhad sheet map based on multipurpose land classification- FAO & Data Bank Softwares of Land Evaluation (DBSLE). Method of simple limitation was used for qualitative evaluation of both methods with scale of 1:250000. In this study, physical and chemical factors which affect the land capability were evaluated without considering the crop yield and socis-economic factors. The location of evaluated area is between 37o -38o E latitude, and 57o -58.5o N longitude with an area of 1472205 ha. Based on FAO method, land mapping units were formed according to physiographic types, limitations and available facilities. Then using DBSLE method, three maps of physiographic type, slope and sensitivity of rocks to weathering (geology) were combined by using GIS software, to produce land mapping units. Capability map for both methods was prepared based on field observation and profile description. The results of this study showed that all the capabilities of physiographic types for both methods were similar, but the capability of hills, plateaus, flood plains and complex lands were different. According to FAO methods, hill, plateau & complex lands were suitable for pasture, but the results of DBSLE methods showed that hills and complex lands were appropriate for irrigation and plateaus were suitable for orchards. With regard to land characteristic, it was found that FAO method has a better evaluation.The results of FAO method showed, flood plains were suitable for pasture, but they were also good for irrigation based on DBSLE method. Unfortunately, chemical factors have not been considered in DBSLE method. Therefore, the results of this method for flood plains were not reliable.Finally, based on these results it was suggested that determination of capability in hills, plateaus and complex lands by DBSLE method must be revised, and for flood plains, important soil chemical factors should be considered.

The increasing demand for food as a result of population growth has led to more pressure on the limited water resources for irrigation. For this reason, increase of yield per unit of water is more important as compared with yield per unit of land. Chemical nutrients are taken up by plant roots in solution form. Thus, an adequate amount of soil moisture is essential to facilitate this process. The objective of this study was to investigate the effect of various irrigation amounts on yield components, efficiency of applied water and fertilizers when used as fertigation. Consequently, a field experiment was carried out with sunflower (Helianthus Annuus L.) as a complete randomized design with 20 treatments and 3 replicates. The fertilizers were applied by fertigation. Four levels of the water (60, 80, 100 and 120% treatments I1 to I4) and five rates of the recommended fertilizers (0, 60, 80, 100, and 120% treatments F0 to F4) were applied. The results indicated that in fertigation method, there were significant differences (p£1%) in total dry matter, grain yield and biomass between treatments.Treatment 14 with 10221 kg ha-1 dry matter, 7365 kg ha-1 biomass, and 2856 kg ha-1 grain yield and treatment II with 6051 kg ha-1 dry matter, 4292 kg ha-1 biomass, and 1760 kg ha-1 gr, ain yield had maximum and minimum yield respectively. Also treatment F1 with 8554 kg ha-1 dry matter, 3301.57 kg ha-1 grain, and treatment F0 with 7065.3 kg ha-1 dry matter had maximum and minimum yield respectively. There were significant differences in water use efficiency (WUE) between 14 and other treatments. On the basis of dry matter WUE, and grain yield WUE, treatment I4 with 1.07 and 0.30 kg m3 had maximum WUE respectively. The results showed that by increasing yield, water use efficiency increased and affected by fertilizers treatments. The results indicated that fertigation method provided the nutrients in readily available forms for plant uptake. Thus due to higher availability of nutrients, yield and fertilizer use efficiency increased, which in turn increased the water use efficiency.

Composting is an effective method to clean up the pollution of municipal wastes from the environment. On the other hand, due to the relatively high content of plant nutrients, it may be applied as an organic fertilizer in agriculture. However, the potential of this compound to contaminate soils with heavy metals should be considered. To manage compost application property on soil, the chemical forms of the heavy metals in soil may be studied by sequential extraction. In this work, effects of municipal waste compost application on chemical forms of zinc (Zn) and copper (Cu) in a calcareous soil were investigated. Different levels of Isfahan municipal waste compost as 25, 50 and 100 Mg ha-1 in comparison with a blank and a chemical fertilizer treatment were examined.The experiment carried out for three years. At the first year, the treatments were applied to the whole plot. At the second year, each plot divided into 1/3 and 2/3 portions and the larger portion received the treatment for the second time. At the third year, the larger portion from the last year divided in two halves, one half left without fertilization and the other half was received the fertilizer for the third time. At the end of the third year, soil samples were taken from 0-25 cm depth in different parts of the experimental plots and analyzed for different chemical forms of Zn and Cu using sequential extraction. The results showed that increase in the amount and the number of municipal waste compost application increased Zn and Cu concentrations in the soluble (SOL), exchangeable (EXE), carbonate (CAR), occluded (OCC) and organic (ORG) forms. The residual form (RES) did not change for Zn, but increased for Cu. The relative distribution of Zn and Cu in different chemical forms were as follows; RES>ORG>OCC>CAR>EXE>SOL. The results showed that most of the Cu and Zn concentrations were in residual and organic forms therefore, very low concentration can enter the food chain.

Immatured municipal compost is not used by farmers because of the presence of different non organic material and bad odor of it. Therefore, hundred tons of produced municipal compost which is a valuable source of organic matter is not applied to soil and it is sometimes considered as an environmental pollutant. This investigation was carried out to examine the possibility of improving the municipal compost quality in a pilot scale. Four different treatments (coarse (C1), fine (F1) compost particle, coarse (C2) and fine (F2) compost particles with two months more incubation) were compared in a completely randomized design in three replications. The results showed that by re-composting process, the temperature of coarse (C1) and fine (F1) particles raised up to 65 and 55°C, respectively. After re-composting, the temperature of compost pile was in the range of matured composts. The ratio of ammonium to nitrate in C1 and find F1 particle compost reduced from 10.7 to 0.36 and from 9.5 to 0.29 respectively. The seed germination assay showed that the seeds did not germinate in the coarse and fine compost particles but after re-composting, all seeds germinated with good vegetative seedling growth. By continuing the re-composting process the, amount of evolved CO2 reduced significantly which is a good index of compost maturity.

One of the problems in agricultural production of dry regions of Iran, is salinity of irrigation water resources, and consequently salt accumulation in soil profile. Subsurface drip irrigation (SDI) is suitable for saline water application.Infact soil solution is kept diluted and salinity effects are not so marked. Moreover, SDI reduces evaporative losses from soil surface and therefore lowers salt accumulation at the soil surface. To study the effects of irrigation water salinity level on salt distribution in soil profile under SDI, an experiment was conducted with two installation depths: 30cm (130) and 60cm (160); three sampling depths: 0-30cm (d15), 30- 60cm (d45), and 60-90cm (d75); and three sampling distances from laterals: 0cm (LO), 100cm (L100) and 200cm (L200); with three replications.Experimental site with pistachio trees is named "Mohamad-Abad farm", which is located in Rafsanjan county. Spatial and temporal variability of soil EC, SAR, CI, Na, Mg and PH, around the emitters, were studied during Mordad 1383 (Aug.2004) to Khordad 1384 (June.2005), once in every four months. The results showed that salts distribution around emitters depends on installation depth, salinity level or irrigation water, soil type and time of the year.Soil EC was maximum for both 130 and 160in Azar 1383 (Nov.2004). In Esfand 1383 (Feb.2005) salinities remained low below the buried laterals, which may be due to application of a high leaching fraction. Soil EC was maximum in dl5 at L200, which might be due to upward flux induced by evaporation from the soil surface, and lateral flow iduced by place of the source at L0. The soil EC values for 130were more than those of 160 for all treatments. CL, Ca, Na and Mg accumulation were similar to EC accumulation. Salts distributions had a decreasing trend with depth and increasing trend with distance from laterals.., Values of soil moisture after irrigation showed that losses due to evaporation was higher for installation depth 30 cm than installation depth 60 cm. Temporal variation of salts was high, and the reasons were postulated due to light soil texture and low initial soil-salinity level. The study results recommends laterals installation at depth of 60 cm to minimize salt accumulation and minimize salinity effects with higher moisture retention.

Different subsurface drainage scenarios including controlled drainage, subirrigation and conventional drainage were studied in a 52 ha. field in northern Iran paddy fields at Amol region using DRAINMOD. The soil texture in the site generally was loam in different layers. In model simulations, 30 year climatic data were used.In each case, different combinations of drain depth and spacing were simulated (drain depth of 1.5, 1.2, and 1.1m and drain spacing of 50, 40, and 30 m for conventional drainage, controlled drainage, and subirrigation, respectively). The results were investigated based on following 8 factors: sum of excess water (SEW), depth of water table, surface runoff, drainage volume, number of working days, relative yield, number of wet days and periods.To compare different scenarios, one combination of the drain depth and spacing was selected. The results showed that sub irrigation is not suitable because of high rainfall in the region. conventional controlled drainage system can be used for these fields, so that in wet season the system acts like a conventional or free drainage system and in paddy rice growh periods, it operates as controlled drainage by installing a weir setting in outlet drain. In all simulations, the excess soil moisture was the main factor for yield reduction and the best conditions of controlled drainage and subirrigation were obrained when the depth of weir setting was the same as Grain depth and these systems acted as conventional drains.

Different analyses of Guelph permeameter and inverse auger hole method were studied to determine the most appropriate method for estimating loamy soils saturated hydraulic conductivity by Guelph permeameter. The experiments were done at Aboureihan faculty research farm, University of Tehran, using randomized completely blocks (as imbalanced with 5 treatments and 21 duplicates).Experiments were analyzed using SAS software version 9.0. Statistical analyses showed that the average of the Richards regression analysis for ponding depth of H=0.15 was the closest method to double head Guelph analysis, and had the highest correlation (r=O.72) with inverse hole method.Also inverse hole hydraulic conductivities were higher than those obtained from Guelph analyses.Based on results, Richards regression analysis was the best method to determine saturated hydraulic conductivity in loamy soils by Guelph permeameter. Also, it recommends the use of the second ponding depth in calculation of Richards analysis.

Among different factors affecting nutrient availability, interaction between micronutrients and organic matter is considered important in bioavailability of these elements to plants. A greenhouse experiment was conducted to study the effects of Zn, Cu, and organic matter and also their interactions on the concentration of Zn, Cu, Fe and Mn in soil and wheat plant. Treatments consisted of three Zn levels (0, 10, and 20 mg kg- soil) in the form of ZnS04.7H20, three levels of Cu (0, 2.5, and 5 mg kg- soil) in the form ofCuS04.5H20, and two levels of organic matter (0, and 2% wt. basis) in the form of cow manure. The experiment was designed with three replications as completely randomized factorial design. Plants were harvested for analysis 45 days after planting. Results indicated that applied Zn increased DTPA-extractable Zn of soil and its concentration in both plant's root and shoot. Zinc also had significant effects on Cu, Fe and Mn concentration in root and only Mn in shoot. Copper application increased DTPA-extractable Cu of soil and Cu concentration in root of plants, but decreased root dry matter weight.Organic matter significantly increased all the measured parameters in this study except Cu concentration in root and shoot.

Drought is one of the major destructive natural disasters. However drought monitoring is very difficult task. Using GIS and RS in drought monitoring is more effective than traditional methods. We used two Landsat images for Mashhad area, one for a wet and the other for a dry year to calculate Normal Deficit Vegetation Index (NDVI).Comparing NDVI derived for the two years, we could detect drought effect on crop production in the area. The cultivated areas were separated from other areas using an image processing procedure and some field works. The derived NDVI for the area was classified into 10 classes.Another index was defined as percentage fraction of the area for each class of NDVI value in the whole area. This index enabled us to compare crop production for the two years. The results showed that NDVI was between 0.5 and 0.7 in wet year and vary between 0.1 and 0.4 in drought year. It was concluded that this method could be used as a basic method for drought monitoring system, if we prepare a reasonable data base of NDVI for a long period of time for the study area.