Effect of different doses of superabsorbent polymer (SAP) on water and nitrogen retention in soil, and on the growth and development of tomato and determination of optimal rate of SAP

In areas of dry climates, water scarcity is an important constraint for food production. The other fundamental factor that limits crop production is availability of nutrients. Balancing the amount of Nitrogen needed for optimum plant growth while minimizing the nitrogen leaching into surface water remains a major challenge. Super-absorbent polymers (SAPs) are known to be soil conditioners which reduce soil water loss and increase crop yield. Use of SAP’s may effectively increase nitrogen use efficiency by minimizing leaching and enhancing nitrogen and water retention. We evaluated total nitrogen and water retention in soils amended with different rates of SAP (0kg of SAP/1000kg of soil without fertilizer (control), 0kg of SAP/1000kg of soil with fertilizer, 0.5kg of SAP/1000kg of soil, 1kg of SAP/1000kg of soil, 1.5kg of SAP/1000kg of soil, 2kg of SAP/1000kg of soil). We determined the effects of the treatments on growth and development of Lycopersicon esculentum Mill. The results indicate that the application of SAP's increased the water holding capacity of the soil. The mean volume of water and nitrates retained in the soils amended with different concentration of SAP’s were significantly different between the treatments(P<0.0001). The results also indicate that incorporating the SAP in the soil significantly improved plant growth parameters like number of leaves, plant height and chlorophyll level(P<0.0001) and yield parameters like number of flowers and fruits(P