PHOSPHORUS MANAGEMENT IN RICE-SORGHUM SEQUENCE
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Date
2018
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Acharya N.G. Ranga Agricultural University
Abstract
A field experiment entitled “Phosphorus management in rice-sorghum sequence” was conducted for two consecutive years (2016-17 and 2017-18) on clay loam soils of Agricultural College Farm, Bapatla. The soil pH was slightly alkaline in reaction and low in organic carbon, low in available nitrogen, medium in available phosphorus and high in potassium.
The experiment consisted of four sources of phosphorus as main plot treatments viz., inorganic fertilizer phosphorus through SSP (M1), green manuring in-situ with dhaincha @ 25 kg ha-1 (M2), phosphorus solubilizing bacteria biofertilizer @ 750 ml ha-1 (M3) and green manuring in-situ with dhaincha @ 25 kg ha-1 + phosphorus solubilizing bacteria biofertilizer @ 750 ml ha-1 (M4); three phosphorus levels to rice as sub plot treatments viz., 50 (S1), 100 (S2) and 150 % RDP (S3) and three phosphorus levels as sub-sub plot treatments viz., 0 (F1), 50 (F2) and 100 % RDP (F3) to succeeding sorghum. All treatments are randomly allocated in three replications in a split plot design for kharif season and split-split plot design for rabi season in both the years of study. The most popular and fine grain quality rice variety i.e., BPT-5204 and popular sorghum hybrid CSH-16 were used during the experimental period.
Data collected on growth parameters, yield attributes, yield and nutrient uptake of rice were subjected to statistical analysis which indicated that all the characters studied were significantly higher with the application of green manuring + PSB (M4) over other sources of phosphorus; however, it was found on a par with that of green manuring (M2) alone whereas significantly lower values were observed with the application of inorganic fertilizer phosphorus through SSP during both the years of study and in pooled data.
Growth and yield parameters of rice were not significantly affected by different levels of phosphorus; however, maximum value was found with 150 % RDP followed by 100 and 50 % RDP during both the years of study and in pooled data.
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A significant interaction between source and levels of phosphorus in rice was observed for drymatter accumulation, the interaction was found to be significant at 60 DAT during 1st year of study with a treatmental combination of green manuring + PSB along with 150 % RDP (M4S3) which was on a par with M4S2, M4S1, M2S3, M2S2 and M2S1 and significantly superior to other treatmental combinations.
Number of grains panicle-1 during 2016-17, grain yield during 2016-17 and 2017-18 showed significant interaction with green manuring + PSB along with 150 % RDP (M4S3) than other treatmental combinations which was at par with M4S2, M4S1, M2S3, M2S2 and M2S1 and significantly superior to rest of the treatmental combinations.
Partial factor productivity for phosphorus was higher with green manuring + PSB (M4) followed by application of green manuring alone (M2). Among the phosphorus levels, 50 % RDP showed higher partial factor productivity during both the years of study.
Growth parameters, yield attributes, grain yield, stover yield, nutrient uptake and economic returns of sorghum were significantly influenced by the source of phosphorus applied to preceding rice but levels of phosphorus did not show any significant effect. Interaction between sources and levels of phosphorus in rice on succeeding sorghum was significant in terms of grain yield during 2016-17 only. With regard to P levels to sorghum, 100 % RDP (F3) was found to be superior over 0 % RDP (F1) but was comparable with 50 % RDP (F2). There was no significant interaction on growth and yield parameters of sorghum among the sources and levels of phosphorus given to rice and levels of phosphorus to sorghum.
The availability of N, P and K status after harvest of sorghum decreased due to high uptake of nutrients during both the years of study. Highest P availability was observed with the treatmental combination of 150 % RDP to rice and 100 % RDP to sorghum (S3F3) which was comparable with S3F2 and significantly superior to other treatmental combinations.
Pooled data of 2016-17 and 2017-18 showed that maximum return per rupee invested of rice-sorghum sequence was recorded with treatment combination of green manuring + PSB, 50 % RDP to rice and 50 % RDP to sorghum (M4S1F2).
From the investigation of two consecutive years with source and levels of phosphorus to rice and levels of phosphorus applied to succeeding sorghum, it can be concluded that the rice-sorghum sequence was profitable with incorporation of green manuring in-situ with dhaincha + PSB along with 50 % RDP to rice, 50 % RDP to succeeding sorghum in Krishna zone of Andhra Pradesh instead of going for higher levels of phosphatic fertilizers thereby getting optimum yield of rice and sorghum and improved soil health.
Description
D5613
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