Standardisation of nutrient and weed management techniques for organic rice

Abstract

The present investigation on “Standardisation of nutrient and weed management techniques for organic rice” was conducted at the Department of Agronomy, College of Agriculture, Vellayani, during 2012-2013. The objectives were to standardise the nutrient schedule, spacing and weed management techniques for organic rice and to assess the economic feasibility of the organic package. The experiment was laid out in the field in split plot design with combination of spacing, S (S1-20 cm x 15 cm and S2-15 cm x 15 cm) and weed management techniques, W (W1-stale seedbed and W2-hand weeding) as main plot treatments and nutrient schedule, N (N1-option-1 of the ad hoc recommendation of KAU: FYM 5 t + 800 kg oil cakes ha-1 (1/2 basal + 1/2 top dressing at active tillering stage), N2-option-2 of the ad hoc recommendation of KAU: FYM 1 t + green leaf manure 1t + dual culture of azolla + 2 kg Azospirillum + 2 kg P solubilizing bacteria + 1kg PGPR (mix 1) ha-1, N3-option-3 of the ad hoc recommendation of KAU: 1/3rd RDN as FYM, 1/3rd as vermicompost and 1/3rd as neem cake + 2 kg Azospirillum + 2 kg P solubilizing bacteria ha-1, N4-soil test based application–half as vermicompost and half as neem cake). The KAU Package of Practices Recommendation (FYM 5 t + 90:45:45 kg NPK ha -1) was taken as control. Closer spacing (S2-15cm x 15 cm), hand weeding (W2) and option-3 of the ad hoc recommendation of KAU (N3) significantly influenced plant height and DMP, while closer spacing (S2-15cm x 15 cm) and option-3 of the ad hoc recommendation of KAU (N3) only had significant influence on tiller production and LAI. Stale seedbed (W1) and closer spacing (S2-15 cm x 15 cm) had significant influence on most of the yield attributing characters, while, among nutrient schedule, N3 (option-3 of the ad hoc recommendation of KAU) attributed the maximum for yield contributing characters, but was on par with N4 (soil test based application) and also with N1 (option-1 of the ad hoc recommendation of KAU) for grain yield. The results on weed control revealed the superiority of closer spacing (S2-15 cm x 15 cm) and stale seedbed technique (W1) over others in controlling the weeds throughout the growth stages. However the weed control efficiency was the lowest in conventional (Control-KAU Package of Practices Recommendation) compared to the organic throughout the growth stages. The nutrient uptake was the highest in N3 (option-3 of the ad hoc recommendation of KAU) and the lowest in N2 (option-2 of the ad hoc recommendation of KAU). However, uptake study had also revealed the superiority of conventional (Control-KAU Package of Practices Recommendation) over organic in the uptake of nutrients. The net returns and B:C ratio were the highest in closely spaced plants (S2-15 cm x 15 cm) and in N3 (option-3 of the ad hoc recommendation of KAU). From the study it can be concluded that for realising higher grain yield in organic rice, a closer spacing of 15 cm x 15 cm (S2) is ideal. Any of the two weed management techniques, i.e., either stale seedbed (W1) or hand weeding (W2) can be practiced for controlling weeds. Option-3 of the ad hoc recommendation of KAU (N3-1/3rd RDN as FYM, 1/3rd as vermicompost and 1/3rd as neem cake + 2 kg Azospirillum + 2 kg P solubilizing bacteria ha-1) is the best nutrient schedule for realizing maximum yield from organic rice. The most economic package for organic rice production is the combination of closer spacing of 15 cm x 15 cm (S2), with stale seedbed technique (W1) of weed control and option-3 of the ad hoc recommendation of KAU (N3-1/3rd RDN as FYM, 1/3rd as vermicompost and1/3rd as neem cake + 2 Kg Azospirillum + 2 Kg P solubilizing bacteria ha-1) as nutrient schedule. The organic package was economically significantly superior to conventional package due to the premium price fetched by organic rice.