Response of Spinach to Nitrogen from Different Nitrogen Sources
Abstract
Nitrogen is a vital mineral element for plant survival especially in vegetables. Spinach is greatly
responsive to nitrogen fertilization and is one of the highest nitrate (NO3) accumulator plants due
to a very efficient uptake system and inefficient reductive systems. A research was carried out at
Makerere University Agricultural Research Institute, Kabanyolo to find out the response of
spinach to nitrogen (N) from different N sources. The main objectives of this research were; (i)
To determine the effect of foliar fertilizer, cow manure and Urea on the growth and yield of
spinach and (ii) To compare the Nitrogen Use Efficiency of Spinach to N from foliar fertilizer,
cow manure and Urea. Three nitrogen sources; Cow manure, Foliar NPK and Urea were used
along with the control to study the response and nitrogen use efficiency of spinach. The
treatments were laid out in a Randomized Complete Block Design and data was collected
periodically within four weeks. The results indicate that Cow manure showed great performance
for all growth parameters with;
plant height (3.573 cm), leaf area (0.196 cm2
) and number of leaves (3.76 leaves), while Urea
showed the least performance for most of the growth parameters with; plant height (3.38 cm),
leaf area (0.097 cm2
) and number of leaves (2.67 leaves). Nitrogen utilization efficiency was
negative in most of the soil amendments except for cow manure and the control. Therefore, soil
laboratory analysis should always be carried out before cultivating land to plant vegetables such
as spinach to avoid excess nitrogen application in the soil due to diverse impacts on both soil and
human health. Organic nitrogen sources such as cow manure are recommended since the plant
nutrient requirement coincided with nitrogen supply due to the slow release, resulting in a better
performance than the other N sources. However, Foliar NPK could be applied when N is
deficient but only at the highest growth stage of the Vegetable.