Use of Azolla in organic farming on availability and uptake of N, P, K of rice paddy (Oryza Sativa, L.)

Organic fertilization is very important to maintain sustainable land and environmental productivity. Organic fertilizer from Azolla has the advantage of increasing soil fertility by increasing nutrient availability. This study aimed to determine the effect of Azolla application on the availability and uptake of N, P, and K of Inpari 32 variety rice plants. This research used 9 treatments: (T0= control, T1= 90 kg/h NPK, T2= 45 kg/h NPK, T3= 10 t/h Manure, T4= 2 t/h Manure + 90 kg/h NPK, T5= 10 t/h Rice straw compost, T6= 2 t/h Rice straw compost + 90 kg/h NPK, T7= 10 t/h Azolla, T8= 2 t/h Azolla + 90 kg/h NPK) with as control and 3 replications, so there were 27 experimental plots. This research was located in the paddy field of Madiun Regency, East Java. The results showed that Azolla, manure, and straw compost at a dose of 10 t/ha increased soil C-organic, soil Cation Exchange Capacity (CEC), and soil pH, which was still in the neutral range. Azolla fertilizer increased the highest soil total N compared to cow manure and straw compost and increased the efficiency of NPK fertilizer use. Azolla (T7) increased soil available P (27.02 ppm) and exchangeable K (17.63 me/100g soil). Azolla had the highest available P effect. Azolla (T7) and manure (T4) were affected by increasing K-exchange. Azolla fertilizer, manure, and rice straw compost increased vegetative plant growth (plant height, number of tillers, shoot and root biomass). Among the three, Azolla fertilizer had the highest effect. Organic fertilization affected N, P, and K uptake, which was highest in Azola fertilizer (T7). For manure, varied NPK fertilizer (T4) just showed an increase in P uptake, and compost fertilizer varied NPK fertilizer (T6) showed a rise in K uptake. A positive relationship existed between the availability and uptake of nutrients N, P, and K.