Munir J. Mohammad

Changes in soil fertility parameters in response to irrigation of forage crops with secondary treated wastewater

Field experiments were conducted to evaluate the effect of irrigation with treated wastewater on soil fertility and chemical characteristics. Three field experiments were conducted at a farmers field near Ramtha Wastewater Treatment Plant. Corn (Zea mays) was planted for two seasons as a summer crop while vetch (Vicia sativa) for one season as a winter crop. Plots were irrigated with either potable water (PW) or wastewater (WW) in amount according to the following treatments: i) potable water equivalent to 100% class A pan reading (PW); ii) wastewater equivalent to 100% class A pan reading (WW1); iii) PW with application fertilizer equivalent to N and P content of WW (PWF) and iv) wastewater equivalent to 125% class A pan reading (WW2). Treatments were replicated 4 times in a randomized complete block design. Soil samples were taken before and at the end of the growing season and were analyzed for soil parameters. WW samples were taken and analyzed periodically for major characteristics. WW analysis indicates inefficient treatment and high values of Biological Oxygen Demand, salt content and reduced form of nitrogen. The results of the field experiments indicate that WW irrigation decreased soil pH and increased soil salinity, soil phosphorus (P), potassium (K), iron (Fe), and manganese (Mn) levels. Soil organic matter increased only in the topsoil and by the highest rate of WW irrigation. This effect could be attributed either directly through the addition of the nutrients and organic compounds to the soil or indirectly through enhancing solubility of soil nutrients. Soil zinc (Zn) and copper (Cu) were not significantly affected by WW irrigation. It can be concluded that secondary treated WW can improve soil fertility parameters, however, more efficient treatment is recommended to reduce salt content. In addition, proper irrigation management and periodic monitoring of soil quality parameters are required to minimize adverse effect on the soil.

TOMATO ROOT AND SHOOT RESPONSES TO SALT STRESS UNDER DIFFERENT LEVELS OF PHOSPHORUS NUTRITION

Abstract Crops differ in their ability to grow under saline conditions and their responses are quite variable and not fully understood. This study was conducted to evaluate the root and shoot responses of tomato to salt stress conditions under different levels of phosphorus (P) nutrition. Tomato seedlings (cv Riogrande) were grown in 500 mL glass jars containing Hoaglands solutions which were salinized by four levels of NaCl salt (0,50,100, and 150 mM NaCl) and/or enriched with three P levels (0.5,1, and 2 mM P) making nine combination treatments. Plants were harvested at the vegetative growth stage and data were collected for root and shoot characteristics. The results indicate that increasing salinity stress was accompanied by significant reductions in shoot weight, plant height, number of leaves per plant, and a significant increase in leaf osmotic potential and peroxidase activity regardless of the level of P supplied. Both root length and root surface area per plant were decreased significantly unde...

Effects of Arbuscular Mycorrhizal Fungi and Phosphorus Fertilization on Growth and Nutrient Uptake of Barley Grown on Soils with Different Levels of Salts

Abstract Greenhouse experiment was conducted to evaluate the effect of arbuscular mycorrhizal fungi (AMF) on plant growth, and nutrient uptake in saline soils with different salt and phosphorus (P) levels. The following treatments were included in this experiment: (i) Soil A, with salt level of 16.6 dS m−1 and P level of 8.4 mg kg−1; (ii) Soil B, with salt level of 6.2 dS m−1 and P level of 17.5 mg kg−1; and (iii) Soil C, with salt level of 2.4 dS m−1 and P level of 6.5 mg kg−1. Soils received no (control) or 25 mg P kg−1 soil as triple super phosphate and were either not inoculated (control) or inoculated with a mixture of AM (AM1) and/or with Glomus intraradices (AM2). All pots were amended with 125 mg N kg−1 soil as ammonium sulfate. Barley (Hordeum vulgar L., cv. “ACSAD 6”) was grown for five weeks. Plants grown on highly saline soils were severely affected where the dry weight was significantly lower than plants growing on moderately and low saline soils. The tiller number and the plant height were also lower under highly saline condition. The reduced plant growth under highly saline soils is mainly attributed to the negative effect of the high osmotic potential of the soil solution of the highly saline soils which tend to reduce the nutrient and water uptake as well as reduce the plant root growth. Both the application of P fertilizers and the soil inoculation with either inoculum mixture or G. intraradices increased the dry weight and the height of the plants but not the tiller number. The positive effect of P application on plant growth was similar to the effect of AM inoculation. Phosphorus concentration in the plants was higher in the mycorrhizal plant compared to the non mycorrhizal ones when P was not added. On the other hand, the addition of P increased the P concentration in the plants of the non mycorrhizal plants to as high as that of the mycorrhizal plants. Iron (Fe) and zinc (Zn) uptake increased with AM inoculation. The addition of P had a positive effect on micronutrient uptake in soil with low level of soil P, but had a negative effect in soil with high level of soil P. Micronutrient uptake decreases with increasing soil salinity level. Inoculation with AMF decreases sodium (Na) concentration in plants grown in soil of the highest salinity level but had no effect when plants were grown in soil with moderate or low salinity level. The potassium (K) concentration was not affected by any treatment while the K/Na ratio was increased by AM inoculation only when plant were grown in soil of the highest salinity level.

Forage Yield and Nutrient Uptake as Influenced by Secondary Treated Wastewater

Abstract The effect of irrigation of forage crops with treated wastewater on the yield and nutrient uptake was evaluated under field conditions. Three field experiments were conducted at a farmers field near Ramtha Wastewater Treatment Plant, Jordan. Corn (Zea mays) was planted for two seasons as a summer crop while vetch (Vicia sativa) was planted for one season as a winter crop during 1994–1995. Plots were irrigated with either potable water (PW) or wastewater (WW) in amounts according to the following treatments: (i) PW equivalent to 100% class A pan reading (PW); (ii) WW equivalent to 100% class A pan reading (WW1); (iii) WW equivalent to 125% class A pan reading (WW2), and (iv) PW with application fertilizer equivalent to nitrogen (N) and phosphorus (P) content of WW1 (PWF). Treatments were replicated four times in randomized complete block design. Plant samples were taken during the growing seasons and were analyzed for dry weight, yield, yield components, and nutrient uptake. The results indicate that WW irrigation increased the yield of both corn and vetch. Both rates of WW application had similar effect on crop production. Supplemental fertilization with the potable water irrigation (PWF) enhanced vetch production and increased grain weight for corn in the second season (1995). The uptake of macronutrients and micronutrients by corn increased with WW irrigation, while the uptake by vetch increased with both WW irrigation and PW supplemented with fertilization. It was concluded that under the conditions of this study, secondary treated WW could be a source of plant nutrients and can be reused for irrigation to increase forage crop production.

Seasonal mycorrhizal colonization of winter wheat and its effect on wheat growth under dryland field conditions

Abstract A field experiment was conducted to determine the seasonal patterns of arbuscular mycorrhiza (AM) in a dryland winter wheat (Triticum aestivum L.) system and to determine wheat growth and P uptake responses to inoculation with mycorrhizal fungus. Broadcast-incorporated treatments included (1) no inoculation with mycorrhizal fungus, with and without P fertilizer, and (2) mycorrhizal fungal inoculation at a rate of 5000 spores of Glomus intraradices (Schenck and Smith), per 30 cm in each row, with and without fertilizer P. Winter wheat was seeded within a day after treatments were imposed, and roots were sampled at five growth stages to quantify AM. Shoot samples were also taken for determination of dry matter, grain yield and yield components, and N and P uptake. No AM infection was evident during the fall months following seeding, which was characterized by low soil temperature, while during the spring, the AM increased gradually. Increases in wheat grain yields by enhanced AM were of similar magnitude to the response obtained from P fertilization. However, responses differed at intermediate growth stages. At the tillering stage, P uptake was mainly increased by P fertilization but not by fungal inoculation. At harvest, enhanced AM increased P uptake regardless of whether or not fertilizer P was added. The AM symbiosis increased with rising soil temperatures in the spring, in time to enhance late-season P accumulation and grain production.

Utilization of applied fertilizer nitrogen and irrigation water by drip-fertigated squash as determined by nuclear and traditional techniques

Field experiments were conducted to evaluate utilization of applied nitrogen (N) and irrigation water to squash in response to method of fertilizer application and rates of fertigation N. The following treatments were studied in a randomized complete block design with four replications: zero N (N0), 50 (N1), 100 (N2) and 150 (N3) mg N L−1 in the irrigation water (IW). Additional soil application treatment (NS) equivalent to N2 was included. The fertilizers were either injected into IW by means of an injection pump for the fertigation treatments or applied directly to the soil followed by irrigation for the soil application treatment. Squash was planted in plots with four rows per plot. Each plant row had its own irrigation line and each plant its own dripper. Irrigation was applied to replenish 80% of the Class A pan evaporation twice a week. Neutron probe readings were taken before and after each irrigation at 15, 30, 45, 60 and 90 cm soil depth. 15N labeled fertilizers were applied to microplots which contained four plants within each plot. At harvest, plant samples were taken from the microplots for the 15N measurements and from the mainplot for yield determination and chemical analysis. Nitrogen uptake and % of N derived from fertilizers (%Ndff) increased with fertigation compared to soil application treatment. N uptake dff had a similar trend as the Ndff. Fertilizer N utilization efficiency (FNUE) by fruits as determined 15N was lower with the soil application than with fertigation treatments and tends to decrease with increasing N fertigation rates. FNUE values calculated by the difference method were higher than those determined by 15N data. All components of FNUE except the recovery efficiency decreased with the soil application method and with increasing fertigation N rates. FNUE correlated positively with squash yield in both seasons but was stronger in the second season. Water consumption increased with increasing N rates. Water use efficiency increased with N application and was higher with fertigation treatment. Water depletion was maximum in the 30 cm topsoil, suggesting the depth of maximum roots growth. It was concluded that yield, FNUE and WUE increased with N fertigation compared to soil application. The difference method tends to give higher FNUE values under relatively less favorable climatic conditions compared to those measured by 15N data. Overall, the results indicate that fertigation is a more efficient technique for fertilizer application to squash.Field experiments were conducted to evaluate utilization of applied nitrogen (N) and irrigation water to squash in response to method of fertilizer application and rates of fertigation N. The following treatments were studied in a randomized complete block design with four replications: zero N (N0), 50 (N1), 100 (N2) and 150 (N3) mg N L−1 in the irrigation water (IW). Additional soil application treatment (NS) equivalent to N2 was included. The fertilizers were either injected into IW by means of an injection pump for the fertigation treatments or applied directly to the soil followed by irrigation for the soil application treatment. Squash was planted in plots with four rows per plot. Each plant row had its own irrigation line and each plant its own dripper. Irrigation was applied to replenish 80% of the Class A pan evaporation twice a week. Neutron probe readings were taken before and after each irrigation at 15, 30, 45, 60 and 90 cm soil depth. 15N labeled fertilizers were applied to microplots which contained four plants within each plot. At harvest, plant samples were taken from the microplots for the 15N measurements and from the mainplot for yield determination and chemical analysis. Nitrogen uptake and % of N derived from fertilizers (%Ndff) increased with fertigation compared to soil application treatment. N uptake dff had a similar trend as the Ndff. Fertilizer N utilization efficiency (FNUE) by fruits as determined 15N was lower with the soil application than with fertigation treatments and tends to decrease with increasing N fertigation rates. FNUE values calculated by the difference method were higher than those determined by 15N data. All components of FNUE except the recovery efficiency decreased with the soil application method and with increasing fertigation N rates. FNUE correlated positively with squash yield in both seasons but was stronger in the second season. Water consumption increased with increasing N rates. Water use efficiency increased with N application and was higher with fertigation treatment. Water depletion was maximum in the 30 cm topsoil, suggesting the depth of maximum roots growth. It was concluded that yield, FNUE and WUE increased with N fertigation compared to soil application. The difference method tends to give higher FNUE values under relatively less favorable climatic conditions compared to those measured by 15N data. Overall, the results indicate that fertigation is a more efficient technique for fertilizer application to squash.

Yield response and nitrogen utilization efficiency by drip-irrigated potato

Two field experiments were conducted in the Jordan Valley to evaluate potato response to N fertigation. Nitrogen as ammonium sulphate was supplied through irrigation water (fertigation) at rates of 0, 35, 70 and 105 mg N l-1. Soil N application treatment equivalent to the fertigation treatment of 70 mg N l-1 was included. 15N labelled ammonium sulphate was used to evaluate the N recovery and utilization efficiency. Yield increased by the N rate. The soil N application gave higher yield than the zero N and lower than the fertigated treatments. The increase in yield was due to the increase in the size of the tubers. The specific gravity was the highest with the zero N. The index ratios of potato tubers were similar with all treatments. The N derived from fertilizers by both tubers and shoots, increased with the N rate regardless of the method of application. The soil application treatments had fertilizer utilization as high as the fertigation treatments and produced total tuber yield not significantly different from that obtained by the fertigation treatment with similar rate. This might be attributed to the poor fertilizer distribution in the root zone in the fine textured soil. The low value of the fertilizer utilization of the plant receiving the 15N in the preceding season suggested possibilities of rapid transformation and immobilization by the soil microorganisms.

Response of bell pepper grown inside plastic houses to nitrogen fertigation

Abstract Two field experiments were conducted for two consecutive seasons inside plastic houses to evaluate bell pepper (Capsicum annuum) response to nitrogen fertigation. Nitrogen fertilizers were applied through irrigation water at rates of zero, 150, 250, and 350 N kg ha‐1. The crops were irrigated in weekly bases with the amount of water equivalent to 80% of the E Pan reading. All treatments were replicated four times in a randomized complete block design. Five plants were sampled from each experimental unit at 30, 60, 90, 120, 150, and 180 days after planting. Growth rate, nutrient uptake and yield were determined. The results indicate that the yield and marketable number of fruits in both seasons increased with the addition of nitrogen. The highest yield was obtained with the addition of 150 kg N ha‐1. The maximum growth rate and the maximum rate of accumulation of dry matter in the fruits occurred during the period of 90 to 150 days after planting. This may indicate that the peak of the pepper N re...

Squash yield, nutrient content and soil fertility parameters in response to methods of fertilizer application and rates of nitrogen fertigation

Two field experiments were conducted to evaluate squash yield and nutrient content in response to different fertigation nitrogen (N) rates and method of fertilizer N application. The following treatments were studied in a randomized complete block design with four replications: zero N (N0), 50 (N1), 100 (N2) and 150 (N3) mg l−3 N concentration in the irrigation water (IW) (fertigation treatments) and a soil application treatment (NS) equivalent to the N2 treatment. Irrigation was applied to replenish 80% of the Class A pan evaporation twice a week. Compared to the control (N0), shoot dry matter and yield were increased by all fertigation N rates and by the soil application treatment. However, soil application gave a lower yield than the equivalent fertigation N rate, indicating the comparative advantage of fertigation. The lowest fertigation N rate was adequate to give the highest yield in the first season, while in the second season a higher rate was necessary to achieve the maximum yield. The growth and fruit yield were higher in the second season as a result of the more favorable climatic conditions. Regression relationships indicate that the yield and the shoot dry weight were related to the fertigation N rates by polynomial quadratic relationships. The response to N in the second season was greater, as indicated by the steeper positive slope. The fruit yield was linearly related to both fruit number and fruit size in both seasons. N contents in shoots increased with N addition and were higher in both fruit and shoot during fruiting with the fertigation method. Soil salinity slightly increased with N application, especially in the top 15 cm, but remained low and acceptable for normal plant growth. Soil P increased mainly in the top soil following phosphoric acid application to all plots. Restricted P movement to deeper soil is attributed to the expected precipitation and/or sorption reactions with Ca and Mg in calcareous soils. It can be concluded that fertigation is more effective than soil application in increasing the yield and with fertigation lower N rates would be adequate to produce higher yield, thus lowering fertilization cost and minimizing environmental impact of over-fertilization.Two field experiments were conducted to evaluate squash yield and nutrient content in response to different fertigation nitrogen (N) rates and method of fertilizer N application. The following treatments were studied in a randomized complete block design with four replications: zero N (N0), 50 (N1), 100 (N2) and 150 (N3) mg l−3 N concentration in the irrigation water (IW) (fertigation treatments) and a soil application treatment (NS) equivalent to the N2 treatment. Irrigation was applied to replenish 80% of the Class A pan evaporation twice a week. Compared to the control (N0), shoot dry matter and yield were increased by all fertigation N rates and by the soil application treatment. However, soil application gave a lower yield than the equivalent fertigation N rate, indicating the comparative advantage of fertigation. The lowest fertigation N rate was adequate to give the highest yield in the first season, while in the second season a higher rate was necessary to achieve the maximum yield. The growth and fruit yield were higher in the second season as a result of the more favorable climatic conditions. Regression relationships indicate that the yield and the shoot dry weight were related to the fertigation N rates by polynomial quadratic relationships. The response to N in the second season was greater, as indicated by the steeper positive slope. The fruit yield was linearly related to both fruit number and fruit size in both seasons. N contents in shoots increased with N addition and were higher in both fruit and shoot during fruiting with the fertigation method. Soil salinity slightly increased with N application, especially in the top 15 cm, but remained low and acceptable for normal plant growth. Soil P increased mainly in the top soil following phosphoric acid application to all plots. Restricted P movement to deeper soil is attributed to the expected precipitation and/or sorption reactions with Ca and Mg in calcareous soils. It can be concluded that fertigation is more effective than soil application in increasing the yield and with fertigation lower N rates would be adequate to produce higher yield, thus lowering fertilization cost and minimizing environmental impact of over-fertilization.

Microbial populations of crude oil spill polluted soils at the Jordan-Iraq desert (the Badia region)

Microbial populations’ inhabitants in crude petroleum contaminated soils were analyzed in relation with the soil characteristics. A noticeable greater decline of bacterial counts and diversity but a prevalence of the genus Pseudomonas over the other identified genera in the fresh contaminated soils as compared to the old ones was observed.