JWSS - Journal of Water and Soil Science

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The objective of this study was to evaluate the characteristics of millet silage prepared in laboratorial mini silos and to determine the effects of additives on its fermentation quality. Whole millet (Panicum milliaceum) was harvested at milk and soft-dough stages of maturity, left untreated or treated with ground barely, molasses, formic acid, lactic acid producing bacteria, and combination of molasses plus inoculant, and were ensiled in a completely randomized design in 2×6 factorial arrangement. Stage of maturity had no significant effect on NDF and ADF, buffering capacity, residual water soluble carbohydrate, acid detergent insoluble nitrogen, ammonia nitrogen and in vitro dry and organic matter digestibility however, values for dry matter, crude protein and pH were significantly different. Loss of dry matter, elevated NH₃-N (24% of total nitrogen) and increased butyric and acetic acid levels (.2 and 1.33% DM, respectively) in control silage indicated clostridial fermentation. Between treatments, the lowest NH₃-N was observed for silages treated with formic acid. Molasses and molasses plus inoculant produced higher lactic acid and lower butyric acid. Higher in vitro dry matter and organic matter digestibility showed positive effects of additive usage compared to control group. Addition of molasses and molasses plus inoculant resulted in higher in vitro dry matter digestibility (63.1 and 64.3 %, respectively), but no significant differences were observed between barely, formic acid and inoculant treated silages. Results of this study clearly showed the need for adding a source of water soluble carbohydrates to millet in order to obtain a good quality silage. Also inoculation of lactic acid bacteria does not necessarily promote homolactic fermentation if insufficient amounts of water soluble carbohydrates are presented.

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The purpose of this study was to evaluate nutritional status in Isfahan dairy herds and the relationship between milk urea nitrogen (MUN) and fertility in the first postpartum insemination. Blood and milk samples were collected from 170 and 290 Holstein cows from 9 dairy herds, respectively. Feed samples were also collected to quantify the relationship between MUN and protein and energy content of the ration. When simple linear regression was used, a close relationship was found to exist between blood and milk urea nitrogen. Regression equations indicated crude protein percentage and protein to energy ratio in the diet only explained 7 and 10 percent of milk urea nitrogen variations, respectively. The low correlation coefficient is probably due to incorrect nutritional management and variation in diet composition in different feeding days. Logistic regression was used to determine the relationship between MUN and fertility. A negative curvilinear relationship existed between MUN and rate of pregnancy at first insemination. Since cows with MUN concentrations of 16.5 to 19 mg/dl had a better chance for pregnancy than those having either below or above these values, it seems likely that pregnancy chances for those cows having this range of MUN concentration are 1.94 and 1.63 times more than cows with less than 14 mg/dl and between 14 - 16 mg/dl, respectively. The results of this study indicated that although MUN is a useful tool for nutritional management of dairy cows, it is not suitable for monitoring reproductive performance.

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To compare the relative value of the fish meal and the cottonseed meal in highly fermentable diets (40% forage and 60% concentrate with), eight cows were assigned randomly to diets with 0, 1.5, 3 and 4.5 percent of the fish meal. In the first experiment, the degradability of dry matter and crude protein of the fish meal, the cottonseed meal and concentrate in diets was estimated with different incubation times (0, 4, 8, 12 and 24 h) with fistulated Ghezel sheep fed at maintenance level. The effective degradability of dry matter and the crude protein of fish meal was significantly lower than cottonseed meal (p<0.05). In different concentrates, there was no significant difference in effective degradability of dry matter but with the increase of fish meal the effective degradability of crude protein decreased significantly. In the second experiment, the eight multiparous Holstein cows with the similar milk production (25.37 ± 0.85) were examined in a replicated 4 × 4 Latin square design with the 21-day period. There were no significant differences between the treatments in digestibility of OM, OM and CP, the dry matter intake, 3.2 % FCM, milk fat (%), milk lactose (%), milk total solid (%), and the yield of the milk fat, feed efficiency and body weights. Diets containing fish meal, compared to the control group, significantly higher milk production, milk protein (%), the yield of milk protein and lactose (p < 0.1), but the different levels of fish meal had no significant effect on these factors. The urea pH decreased significantly with the increase of the fish meal but rumen pH and fecal pH were unaffected. The results of the experiment indicated that diets with the 1.5 or 3% fish meal in cows with less than 30 kg milk is recommended.

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Saturated hydraulic conductivity (Kfs) and macroscopic capillary length of soil pores are important hydraulic properties for water flow and solute transport modeling. Measuring these parameters is tedious, time consuming and expensive. One way is using indirect methods such as Pedotransfer functions (PTFs). The objective of this research was to develop some PTFs for estimating saturated hydraulic conductivity and inverse of macroscopic capillary length parameters (*). Therefore, the coefficients, Kfs and * from 60 points of Azadegan plain in Shahrekord were measured using single ring and multiple constant head method. Also, some of the readily available soil parameters from the two first pedogenic layers of the soils were obtained. Then, the desired PTFs were developed using stepwise multiple linear regression. The accuracy and reliability of the derived PTFs were evaluated using root mean square error (RMSE), mean error (ME), relative error (RE) and Pearson correlation coefficient (r). The highest correlation coefficients of 0.92 and 0.72 were found between Kfs-bulk density and *-bulk density, respectively. There was no significant correlation between soil particle size distribution and Kfs and *. This can be related to the fact that most of the soil samples were similar in texture and macro pores. The most efficient PTFs in predicting Kfs and * could explain 85 and 66 percent of the variability of these parameters, respectively. All the derived PTFs underestimated the Kfs and * parameters.

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Free and uncontrolled pasture grazing by animals may decrease soil aggregate stability through reductions in plant cover and subsequent soil organic C, and trampling. This could expose the soil surface layer to degradation and erosion. The objective of this study was to determine the influence of pasture management (free grazing, controlled grazing and long-term non-grazing regimes) on aggregate-size distribution and aggregation parameters by wet and dry sieving methods in two native pastures, protected areas in Chaharmahal va Bakhtiari province. The studied pastures were 1) SabzKouh pastures protected from grazing for 20 years, and 2) Boroujen pastures protected from grazing for 25 years. Soil samples were collected from 0-15 cm depth during the grazing season in summer 2008. Samples (finer than 2 mm) were analyzed for aggregate-size distribution and aggregation parameters by wet and dry sieving methods. Results showed that pasture management had a significant influence on aggregate-size distribution and aggregation parameters in the two areas. The two methods indicated that macro-aggregates in non-grazing and controlled grazing regimes were higher than those in free grazing regime, whereas in free grazing management micro-aggregates showed an opposite trend, and were greater compared with the other grazing regimes. Similarly, soil aggregate stability indices (i.e. mean weight diameter, aggregate geometric and ratio mean diameter) were all improved by non-grazing regimes, suggesting that animal grazing and trampling break down large soil aggregates due largely to compaction and reduced plant coverage. However, the extent to which grazing affects soil aggregation depends in large part on grazing intensity and duration, and the area involved.

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Change in land use and tillage practices has great influence on soil physical and chemical properties. The present study has focused on the effects of converting undisturbed soil to agricultural lands. Chemical and physical soil properties, infiltration, cation exchange capacity (CEC), electrical conductivity, pH, bulk density, porosity, sodium, potassium, total Ca + Mg, organic matter percentage, sodium adsorption ratio (SAR) and lime percentage were measured using standard frequently used methods. Fifty soil samples from agriculture land and other 50 soil samples from undisturbed land were collected from 0 – 30 cm depth and different statistical analysis were performed. Agriculture land is Cultivated for more than 20 years. The results showed that change in land use from undisturbed to disturbed soil did not significantly changed soil organic matter content. Also, soil electrical conductivity showed a huge increase whereas pH showed non-significant changes due to land use change. Unlike pH, SAR, organic matter percentage and lime percentage, some other soil parameters showed significant decrease in quality through land use change. Correlation coefficients of the effective factors were calculated to explain the main reason for lowering soil quality. The results showed that sodium in EC bulk density in porosity and CEC sodium and Ca+Mg in SAR EC in soil infiltration and Ca+Mg in organic matter showed the most correlation.