Potassium and calcium nutrition improves potato production in drip-irrigated sandy soil

Abstract

The response of Spunta potato (Solanum tuberosum L.) plants to different rates of potassium (60 and 120 kg Fed-1 ) in presence or absence of Ca nutrition was studied. The study was performed in sandy-loam soil under a drip-irrigation system during fall seasons of 1996 and 1997 years. Plants fertilised with high rate of K (120 kg K. Fed-1) showed 25-30% increase in fresh weight of tubers and lower fresh weight of foliage at 75 and 90 days after planting (DAP) as compared to those of low K (60 kg K. Fed-1). This resulted in at least 50% higher tuber/foliage ratio of high K treated plants at 75 and 90 DAP. Also, plants that received higher rate of K showed 10-20% increase in multiplication rate as compared to those plants that received low K. High K fertilised plants consistently gave 10-20% more tuber yield than those receiving lower dosage. The marketable yield exhibited the same trend as total yield. Compared with low rate of K application, high rate increased yield of medium (28-60 mm) and over-sized tubers (> 60 mm) by about 15 and 40%, respectively. Calcium showed fluctuating effect on all yield parameters during the two seasons of study. The injection of soluble form of calcium fertiliser increased calcium concentration in peel and medulla tuber tissues as compared to non-calcium treated plants even in soil which contained enough calcium for vegetative growth. It is concluded that K nutrition is a key factor for potato production in sandy soils and studies with emphasis on the relationship between soil exchangeable K and K fertilisation rate as well as variety requirement for different production purposes should be continued. Our results also suggest a potential for improving tuber Ca-content by application of soluble form of calcium fertiliser during bulking even in soil containing sufficient calcium for optimum vegetative growth.



Key Words: Egypt, mineral nutrition, sandy soils, spunta potato


(African Crop Science Journal 2001 9(1): 147-156)