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A field experiment was conducted on a gypsiferous sandy clay loam soil to examine the effects of blending Triple superphosphate (TSP) with urea on N, P concentrations in plant and growth parameters of broad bean. The experiment was a factorial randomized complete block design (RCBD) with three replicates. The first factor was type of application as briquettes which include T1 (one layer of TSP between two layers of urea) and T2 (one layer of urea between two layers of TSP), the second factor was application depth (5 and 10 cm D1 and D2), and the third factor was application rate (1.0, 1.25, and 1.50 as much as N and P fertilizer recommended for broad bean, R1, R2 and R3). Broad bean was planted and the following growth parameters were taken: plant height, no. of leaves, plant dry weight, chlorophyll content, leaf area, N and P concentration in plant. Results showed that the following treatments: T1 of blending (briquette no. 1), D1 and R2 were significantly superior over other treatments in all growth parameters and N, P concentration in plant. The triple interaction treatment T1D1R2 was significantly superior over other treatments with values reached 60.99 cm, 442.7 leave plant-1, 20.32 cm2, 63.87 Spad, 5.59 g plant-1, 5.55 %, and 0.27 %, respectively for plant height, no. of leaves plant-1, leaf area, chlorophyll content, plant dry matter, N and P conc. in plant.

Gypsiferous soils in Iraq are suffering from low fertility due to low levels of organic matter and limited availability of nutrients especially phosphorus (P). Therefore, two experiments were conducted to study the impact of combination of low cost phosphate rock (PR) and organic materials (OM) on soil organic carbon (SOC) and P status. The first experiment was an incubation experiment which was conducted to determine level of organic carbon (OC) required for the second experiment, this experiment was consisted of two factors the first was level of OC (as sheep manure) applied at nine levels viz: 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, and 0.60% of soil weight, the second factor was level of PR (0, 20, 40, and 60 mg P kg-1 soil). The second experiment was a greenhouse pot experiment with two factors, the first was P source [Triple Super Phosphate (TSP), PR, PR+ Peat, and PR+ Manure), the second factor was P level (0, 30, 60, and 90 mg P kg-1 soil). Wheat (Triticum aestivum) was grown in the second experiment. Results from incubation experiment showed that increasing OC application increased available P (Avail. P) and Water Soluble P (WSP) as expressed by power and exponential models, respectively. Available P was also increased linearly by increasing P level in soil (incubation experiment). Results of pot experiment revealed that the fourth treatment (PR+manure) was significantly superior over other treatments in increasing root weight, organic P (OP), and Avail. P, while the third treatment (PR+Peat) was significantly superior over other treatments in increasing SOC.