Kajian Hubungan Populasi Tanaman dengan Neraca Unsur Hara Nitrogen dan Fosfor pada Sistem Vertikultur Sawi Hijau (Brassica juncea L) dan Kangkung (Ipomea reptana)

The relationship between crops density and the balancing of both soil nitrogen and phosphorus in verticulture system remained to be important issue. A glasshouse experiment had carried out from October 2014 to March 2015 in order to determine (1) the optimum population density of both mustard greens (Brassica juncea L) and kale (Ipomea reptana), (2) soil total-N or available-P balance, and (3) the relatiohships between plants populations and soil nutrients balance. A split plot experiment under complete block design was applied to examine the effect of the main plot (crops type i.e. mustard green and kale) and sub plot (crops population i.e 10, 15, 20,25, and 30 crops per planting container 0,12 m2 in size). The results showed that no optimal crops population density had achieved. The maximum crops population was 30 for both mustard greens and kale. The soil total-N balance was negative while these was positive for soil available-P balance of P and N negative. A logarithmic relationships was calculated between soil total-N balance with mustard green, while linier patterns were significant for soil-N balance with kale and available-P balance with both mustard greens and kale.