Oil palm leaf ash's effect on the growth and yield of Chinese cabbage (Brassica rapa L.)

The production of Chinese cabbage (Brassica rapa L.) has not been able to keep up with consumers' demand. Appropriate application of fertilizers is a key element in boosting plant productivity. One of the problems faced when fertilizing is that plant nutrient uptake has low efficiency. The application of basic nitrogen–phosphorus–potassium (NPK) fertilizers is typically the main emphasis of traditional agriculture, whereas the need for micronutrients, including Si, receives less consideration. Organic and inorganic materials are sources of Si nutrients. Currently, organic materials include straw or rice husks. The use of oil leaf palm waste as a source of nutrients is relatively still rare. The oil palm leaf ash in the production of Chinese cabbage is still not yet been researched. This analysis aims to know the optimal of oil palm leaf ash for the growth and yield of Chinese cabbage. The growth parameters measured 40 days after planting: leaf number, plant height, crown diameter, and fresh weight were impacted by the usage of oil palm leaf ash. A combination of oil palm ash at a concentration of 3.75 kg/m2 and manure at a concentration of 1500 kg/m2 produced the greatest results. In general, the usage of oil palm leaf ash affected the growth of Chinese cabbage, but the results could not be statistically separated from the role of manure as a source of NPK for plants. It was also demonstrated that the use of oil palm leaf ash increased the resistance of Chinese cabbage to armyworms. Therefore, Si for agriculture it can be utilized from oil palm leaf ash as a natural source.