EFFECT OF FRESH AND COMPOSTED AZOLLA ON RICE GRAIN YIELD AND QUALITYTiemour Razavipour, Mojtaba Rezaeii, Ebrahim Amiri and Hassan Ebrahimi Rad
Composting fresh Azolla with rice straw can be an effective way for facilitating the N usage by the paddy crop. A study was initiated to compost fresh Azolla with rice straw and compare the effectiveness with fresh Azolla at different dosage levels on paddy grain yield and grain quality. A suitable dosage of composted Azolla with rice straw (ARS) as a bio-fertilizer was identified for popularly grown rice variety Hashemi with and without use of supplementary chemical fertilizers by laying out an experiment in factorial randomized complete block design with three replications in silty clay soils of Guilan province, Iran. The six treatments were T1 to T4 included 3, 5, 7, 10 and 12 tones of composted ARS respectively, T5 treatment was tonnes of composted ARS with Urea=120 kg given in two equal splits at basal and one month after transplanting and T6 treatment was 6 tonnes of fresh Azolla. These treatments were effectively compared with the control I without any fertilizer and control II with recommended dosage of chemical fertilizer for grain yield. ANOVA results clearly revealed that the bio-fertilizer treatments differed significantly for only for grain yield however for all other traits it showed non significant differences. Highest grain yields were observed in T5 treatment. However, the composted ARS treatments with 5, 7, 12 tones gave significantly higher grain yields as compared to control I. Interestingly, 6 tonnes of fresh Azolla (floating) was observed to be detrimental to grain yield in Iranian conditions as its yields were significantly lower than the control- I. Nutritional source to the plant from soil or chemical or bio-fertilizers had no significant effect on grain quality i.e. PC, AC, GT, GC of rice. We recommend applying of 5 tonnes composted ARS with Urea=120 kg given under Iranian conditions to save completely on P and K and other micronutrients as compared to recommended N.P.K. for getting a yield advantage of 10 %. The same treatment is beneficial for grain yield over control I by 29%.
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