Journal of Agricultural Science; Vol. 7, No. 3; 2015 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 66 Interaction of Phosphorus and Potassium on Maize (Zea mays L.) in Saline-Sodic Soil Z. Hussain 1 , R. A. Khattak 2 , I. Fareed 3 , M. Irshad 4 & Q. Mahmood 4 1 Department of Development Studies, COMSATS Institute of Information Technology (CIIT), Abbottabad, Pakistan 2 CECOS University of Information Technology and Emerging Sciences, Hayatabad Peshawar, Khyber Pakhtunkhwa, Pakistan 3 Department of Natural Resources Engineering and Management, University of Kurdistan, Hewler, Iraq 4 Department of Environmental Sciences, CIIT, Abbottabad, Pakistan Correspondence: M. Irshad, Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad, Pakistan. E-mail: mirshad@ciit.net.pk Received: December 8, 2014 Accepted: January 6, 2015 Online Published: February 15, 2015 doi:10.5539/jas.v7n3p66 URL: http://dx.doi.org/10.5539/jas.v7n3p66 Abstract Salinity and nutrient deficiencies are the main constraints for high crop productivity. Interaction of diammonium phosphate and potassium sulphate in saline-sodic soil for maize (Zea mays L.) crop was investigated. The results demonstrated that maize responded well to K and P fertilization in saline-sodic soils. The effects of salinity and sodicity were ameliorated by the application of K and P fertilizers resulting in higher yield. K had greater influence on grain yield than P level. K application increased yield related parameters. The addition of P significant affected leaf [P] and [Na] content, Na:K and Ca:Na ratios. Potassium levels had significant effects on [Na], [K], [Mg] and Na:K ratio. Phosphorus and K interactions did not affect leaf chemical composition except Mg content. The P application resulted in an increase of [P] in maize leaf tissue as compared to control. A decrease in [Na] and Na:K ratio was observed with the addition of K. There was positive relationship between grain yield (R 2 = 0.67), dry matter yield (R 2 = 0.76) and leaf [P], respectively in soils treated with P. The tissue [Ca], ratios of Ca:K and Ca:P were non-significantly affected by the K and P treatments. Extractable [P] increased after P treatments in the soil. The application of K significantly decreased Na:K ratios in the soil. The decreasing trends of [Na] and Na:K ratios depicted a negative (R 2 = 0.91) correlation between Na:K and soil [K]. Such interaction of K and P could mitigate the adverse effects of salinity and sodicity. Keywords: saline-sodic soil, maize, plant growth, phosphorus, potassium, nutrient concentration 1. Introduction Global estimates on the soil salinity greatly vary for various regions (Flowers et al., 1986). About one-third of total global 160 million ha irrigated land (equivalent to 53 million ha), is salt-affected, which is a major constraint for sustainable agricultural activities and crop yields (Greenland, 1984). Poor management practices along increased use of saline water for irrigation have aggravated the problem (Framji, 1976). The accumulation of excessive soluble salts and/or exchangeable sodium is confined to arid and semi-arid lands. In the Indian subcontinent, highly salt-affected soils occur in India and Pakistan (Rashid, 2006). In addition to other soil physic-chemical stresses which decrease crop yields; salinity and sodicity also adversely affect soil fertility (Rashid, 2006). Intensive cropping and severe climatic conditions affect the land use due to poor fertility status of the soils. The production demands are increasing due to the growing human population. The immense potential of salt affected soils for much needed food production, fibre, fuel and forage crops is now more desirable than ever. The researchers and scientists continue their efforts to find out the proper management of degraded and salt affected lands for better crop production. Understanding the salt and nutrient interaction are important to evaluate the impacts on crop productivity under such soil conditions. The salt tolerance of a crop depends upon whether salinity or nutrition is limiting the growth of plant (Maas & Hoffman, 1977). Studies related to salinity and nutrient interaction are commonly performed either in nutrient culture or soil culture both in the laboratory and glasshouse and sometimes in the field depending upon the