The research study was carried out at the Agricultural Experimental Research Station located at Hada Al-Sham, King Abdulaziz University during two successive seasons (2015-2016 and 2016-2017) to study the effects of different organic fertilizers (cow manure, sheep manure, cow manure + barley straw and sheep manure + barley straw) and NPK (20:20:20), under two irrigation methods (surface and subsurface drip irrigation), and three water supply rates (100%, 80% and 60%), on yield , yield components of Cabbage (Brassica oleraecea L) and soil chemical properties in split- split plot design in 4 replicates. For irrigation systems, the subsurface drip irrigation (SDI) system dominated surface drip irrigation (DI) system, and for IWR, the 100% rate dominated followed by 80% and then 60%, and for organic fertilizers , the NPK dominated , seconded by sheep manure, then cow manure , then sheep manure + barley straw, then cow manure + barley straw, as regards mean values of all cabbage yield and yield components , and soil pH, EC and organic matter (OM).

This study was conducted at the Agricultural Experimental Research Station located at Hada Al-Sham, King Abdulaziz University during two successive seasons (2015-2016 and 2016-2017) to study the effects of different organic fertilizers (cow manure, sheep manure, cow manure + barley straw and sheep manure + barley straw) and NPK (20:20:20), under two irrigation methods (surface and subsurface drip irrigation), and three water supply rates (100%, 80% and 60%), on growth components of Cabbage (Brassica oleraecea L) and soil content of the macro-elements N, P, K in split- split plot design in 4 replicates .The subsurface drip irrigation (SDI) system dominated the surface drip irrigation (DI) system, and the 100% irrigation water rate was better than 80% and then 60%, and the NPK dominated organic fertilizers , seconded by sheep manure, then cow manure , then sheep manure + barley straw, then cow manure + barley straw, as regards mean values of all cabbage growth components of, head ,stem, leaves , root, and total plant fresh and dry weight and the highest soil content of NPK .

Discriminate use of fertilizers gradually damaging biological and physical properties of soil as well as bioavailability of nutrients and organic matter resulting results in low crop yield. So there is needed to equilibrate the application of inorganic fertilizer with organic fertilizers especially in arid region of Saudi Arabia to sustain and conserve soil resources for long term and better yield results. A field experiment was carried out at the Agriculture Research Station of King Abdulaziz University to investigate the effect of different rates of humic acid application along with inorganic fertilizers on growth components of mung bean (Vigna radiata) crop and soil properties. The design of the experiment was a completely randomized design with four replications. Three treatments of humic acid (HA 20, 20kg/ha; HA 40, 40kg/ha and HA 60, 60kg/ha) along with control (HA 0) was applied. Results indicates that humic acid application caused significant improvement in the growth parameters of mung bean crop at all levels and (HA 40) proved to be optimum application rate for growth improvement. Regarding soil parameters, a significant decrease in pH was observed at (HA 40), while significant decrease in EC was observed at (HA 40). For soil fertility parameters, HA 40 (40 kg/ha) and HA 60 (60 kg/ha) significantly increase the availability of primary macronutrients (N, P and K) in the soil. The results suggested that application of humic acid at optimum rate HA 40; 40 kg/ha) improves plant and soil attributes to play an important role in sustainable agriculture.

Proper management and use of resources is well necessary to obtain sustainable and economic results especially in marginal land areas like arid lands of Saudi Arabia. To attain the above mention feathers a field experiment was carried out at the Agriculture Research Station of King Abdulaziz University to evaluate the comparative effect of humic acid application methods and rates on seed yield and yield components of mungbean and some soil micronutrients in arid region of Saudi Arabia. A two factor factorial under randomized complete block design was used in this experiment with four replications. Two methods of humic acid application (solid vs liquid) and Three treatments of humic acid (HA 20, 20kg/ha; HA 40, 40kg/ha and HA 60, 60kg/ha) along with control (HA 0) were applied. Results indicate that application of humic acid in solid form resulted in significant improvement in yield and yield components (shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, hundred seed weight and seed yield). Regarding rates, increasing HA ratesincreased all yield and yield components. Significant increase in all yield components was observed at first three levels of humic acid rates (HA 0 kgha-1 To HA 40 kgha-1), while increasing humic acid rate from (40 to 60 kgha-1) all yield and yield components were statistically similar except seed yield. It is concluded that interaction of solid application method with increasing rates of humic acid upgraded yield and yield component of mungbean and enhance the micronutrients (Cu, Zn and Mn) status in soil solution under arid land region of Saudi Arabia.

A field experiment was carried out at Agriculture Research Station of King Abdulaziz University, Jeddah, Saudi Arabia to study the effect of fine particles, tillage system, and polyacrylamide application rate on the soil penetration resistance during the two seasons (2015/16 – 2016/17). Experimental design was split-split plot with four replications. Main plot included two percent of fine particles, (A = 25.2 silt + clay) and (B = 38.5 silt + clay). Sub-main plots included three tillage systems; no-tillage (NT), moldboard plowing with rotor tiller (CT1), and chisel plowing with disk harrow (CT2). Sub-sub plots were three polyacrylamide (PAM) rates; 0, 10 and 20 kg ha-1. Both locations were cultivated by wheat crop for two consecutive seasons. Results revealed that tillage system affected soil penetration resistance. Penetration resistance results revealed the existence of compacted layer beneath the tilled depth in all treatments in both locations. However, its hardness in location A was higher than in location B. The CT1 treatment had the highest value of cone index; however, the penetration resistance of CT2 and NT treatments was similar. High rate of PAM application improved penetration resistance especially with CT2 tillage system.

A field experiment was carried out at the Agriculture Research Station of King Abdulaziz University to study the effects of fine soil particles, tillage system and polyacrylamide on wheat production and some soil chemical properties. The design of the experiment was a split-split plot with four replications. The main plot included two soils A and B, (A with 25.2 % silt+ clay while B with 38.5 % silt+ clay). Sub plot included three tillage systems namely: No-tillage (NT), Moldboard ploughing with rotor tiller (CT1) and Chisel ploughing with disk harrow (CT2). The sub-sub plot included three polyacrylamide (PAM) rates and were 0, 10 and 20 kg/ha. The obtained results indicated that soil of location B was better than the soil A because wheat production in location B was significantly higher than that of location A. CT2 produced the highest grain yield for wheat crop followed by NT and CT1 tillage systems respectively. Application of different rates of PAM (10 and 20 kg/ha) increased yield production compared with 0 kg/ha. Soil nutrients including N, P and K were significantly increased in the soil of location B compared to location A. The nutrients also increased by increasing PAM rates in both locations.

Field experiments were carried out for two consecutive seasons at the Experimental Station of Soil and Water Department‚ Faculty of Agricultural‚ Assiut University, to study the effect of both irrigation intervals and methods of potassium application on yield and yield components of wheat (Triticum aestivum L.) beside potassium content in plant and soil. The experimental design was a split plot design with four replications. The main plots were three irrigation intervals (15, 21 and 28 days), while the sub- plots contained two methods of potassium application (side dressing and fertigation). Results indicated that, shorter irrigation intervals improved yield and yield components of wheat crop. The best yield was obtained from 15 days irrigation interval followed by 21 days. Longer irrigation interval (28 days) produced the least yield and yield components due to water stress conditions. Applying potassium with irrigation water improved yield of wheat crop and potassium contents in grain and straw yields compared to side dressing application. Also it increased the available potassium in soils.

Field experiments were carried out for two consecutive seasons at the Experimental Station of Soil and Water Department‚ Faculty of Agricultural‚ Assiut University, to study the effect of both irrigation intervals and methods of potassium application on yield and yield components of wheat (Triticum aestivum L.) beside potassium content in plant and soil. The experimental design was a split plot design with four replications. The main plots were three irrigation intervals (15, 21 and 28 days), while the sub- plots contained two methods of potassium application (side dressing and fertigation). Results indicated that, shorter irrigation intervals improved yield and yield components of wheat crop. The best yield was obtained from 15 days irrigation interval followed by 21 days. Longer irrigation interval (28 days) produced the least yield and yield components due to water stress conditions. Applying potassium with irrigation water improved yield of wheat crop and potassium contents in grain and straw yields compared to side dressing application. Also it increased the available potassium in soils.

Field experiments were carried out for two consecutive seasons at the Experimental Station of Soil and Water Department‚ Faculty of Agricultural‚ Assiut University, to study the effect of both irrigation intervals and methods of potassium application on yield and yield components of wheat (Triticum aestivum L.) beside potassium content in plant and soil. The experimental design was a split plot design with four replications. The main plots were three irrigation intervals (15, 21 and 28 days), while the sub- plots contained two methods of potassium application (side dressing and fertigation). Results indicated that, shorter irrigation intervals improved yield and yield components of wheat crop. The best yield was obtained from 15 days irrigation interval followed by 21 days. Longer irrigation interval (28 days) produced the least yield and yield components due to water stress conditions. Applying potassium with irrigation water improved yield of wheat crop and potassium contents in grain and straw yields compared to side dressing application. Also it increased the available potassium in soils.

This study was performed to evaluate the effect of both cow and chicken manures application on the immobilization of Ni and Zn in soils. Effect of cow and chicken manures on the bulk density, pH and the distribution of Ni and Zn in various chemical fractions of an alkaline, sandy loam soil was explored in a PVC columns study. Cow and chicken manures were mixed at rates of 10, 20 and 30 g/kg of soil. The soil-manure mixture was incubated for two months at room temperature. Sequential extraction procedure was performed on all samples from each column to determine Zn and Ni in different fractions (soluble-exchangeable, organic, carbonates and residual). Results obtained showed a decrease in soil bulk density with an increase of 0.3 units in soil pH as compared to the control. After 60 days of incubation, Ni concentrations were found to be 28 and 34% of inorganic fraction, while the residual reaction accounted for 58 and 53% for cow and chicken manure respectively as compared to the corresponding control. In case of Zn, soil organic matter fraction accounted for 53-57% of the total Zn. The soluble and exchangeable fraction which, although, slightly increased with time remained very low (2-4%) for the two metals. Therefore, the addition of the manures resulted in improved soil bulk density and showed a good potential in immobilizing both two metals in the studied soil.