1. Al-Omran AM, Sheta AS, Falatah AM, Al-Harbi AR (2005) Effect of drip irrigation on squash (Cucurbita pepo) yield and water-use efficiency in sandy calcareous soils amended with clay deposits. Agric Water Manag 73:43–55
2. Al-Omran AM, Sheta AS, Falatah AM, Al-Harbi AR (2007) Effect of subsurface amendments and drip irrigation on tomato growth. WIT Trans Ecol Environ 103:593–601
3. Al-Omran AM, Al-Harbi AR, Wahb-Allah MA, Mahmoud N, Al-Eter A (2010) Impact of irrigation water quality, irrigation systems, irrigation rates and soil amendments on tomato production in sandy calcareous soil. Turk J Agric For 34:59–73
4. Baligar VC, Bennett OL (1986a) NPK-fertilizer efficiency- a situation analysis for the tropics. Fertil Res 10:147–164
5. Baligar VC, Bennett OL (1986b) Outlook on fertilizer use efficiency in the tropics. Fertil Res 10:83–96