INTEGRATED NUTRIENT MANAGEMENT OF rabi SWEET SORGHUM (Sorghum bicolor L. Monech) IN PONGAMIA BASED AGRISILVICULTURE SYSTEM
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Date
2009
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD
Abstract
The present study entitled “Integrated nutrient management of rabi Sweet
sorghum (Sorghum bicolor L. Monech) in Pongamia based agrisilviculture system” was
conducted in red sandy loams in Agroforestry research block, Acharya N.G. Ranga
Agricultural University campus, Rajendranagar, Hyderabad. The field experiment was
laid out in randomised block design with 9 treatments replicated thrice. The treatments
consists of combination of three types of manures such as poultry manure (PM),
vermicompost (VC), FYM and two types of biofertilizers Azospirillum and VAM with
75 % recommened dose of N, besides individual 100 % RDF (NPK @ 80-60-40 kg ha-1)
and FYM @ 10 t ha-1 compared to control without manure and fertilizer.
Integrated use of 75 % RDN along with 25 % N through PM significantly
influenced the dry matter production (18.56 q ha-1) on par with 100 % RDF (17.53 q ha-1)
closely followed by 75 % RDN + 25 % N through VC (16.01 q ha-1) at 60 DAS. Plant
nutrient composition of N, P, K and Zn, Fe, Cu, Mn was significantly influenced by
different treatments over control. The highest content was recorded due to combination
of 75 % RDN + 25 % N through PM with a values 3.55, 0.325, 3.55 % and 31.85, 86.72,
6.01, 53.28 mg kg-1 respectively. The increase in concentration of nutrients appears to be
due to enhanced availability of nutrients, uptake of nutrients and increased plant growth.
The uptake of nutrients in Sweet sorghum was significantly more in conjoint use of 75 %
RDN along with 25 % N through PM at 60 DAS.
The grain and stover yield at harvest was effected significantly by different
treatments over control. Application of 100 % RDF (NPK @ 80-60-40 kg ha-1) registered
highest grain (30.78 q ha-1) and stover yield (92.25 q ha-1) followed by 75% RDN + 25 %
N through PM (28.50 and 84.65 q ha-1). Regarding quality parameters the maximum brix
(12.40 %) and sucrose content (9.86 %) was recorded in combined treatment i.e. 75 %
RDN + 25 % N through PM which was significantly superior over control.
Irrespective type of manure and biofertilizer combination with inorganic fertilizer
significantly increased the nutrient concentration and uptake of nutrients by grain and
stover. Among them the best nutrient management treatment is 75 % RDN + 25 % N
through PM followed by 75 % RDN + 25 % N through VC. Total uptake of nutrients by
Sweet sorghum also showed similar pattern as was observed in corresponding grain and
stover uptake.
The soil pH and EC at both 60 DAS and harvest was not changed significantly by
different treatments over initial values. The organic carbon content indicate that there was
significant effect by different treatments over control in general. But, in particular high
OC content was observed in manurial treatment combinations. Out of which maximum
OC content and moderate build up over control was registered in 75 % RDN + 25 % N
through PM at 60 days period and harvest (0.57 and 0.63 %).
The status of available nutrients (N, P, K) was significantly influenced by type of
manure and biofertilizer with inorganic fertilizer. Among them the highest content was
found under nutrient management practice followed by 75 % RDN + 25 % N through
PM at both 60 DAS and harvest (215.49, 22.84, 228.36 kg ha-1 and 242.72, 23.96, 233.44
kg ha-1). The superiority of poultry manure than other two manures is due to higher
nutrient composition, faster mineralization and low C:N ratio. Similar pattern was
followed in the same treatment with respect to available Zn, Fe, Cu and Mn at both 60
DAS and harvest (1.38, 9.53, 2.24, 14.56 mg kg-1 and 1.72, 9.72, 2.28, 14.68 mg kg-1
respectively). Between biofertlizer combination treatments, inoculation of both
Azospirillum + VAM @ 5 kg ha-1 each with 75 % RDN was relatively better than non
inoculation and sole application of FYM 10 t ha-1 in terms of available major and micro
nutrients at both 60 DAS and post harvest stage.
Different types of manure and biofertilizer combination with chemical fertilizer
significantly influenced the soil enzyme activity such as urease, dehydrogenase, acid and
alkaline phosphatase at 60 DAS and harvest. The soil enzyme activity was maximum at
60 days duration of crop growth and gradually decreased up to harvest stage of crop
growth. The highest content of different soil enzyme activity was observed with conjoint
use of 75 % RDN + 25 % N through PM at both 60 DAS and harvest.
Based on the results it was concluded that integrated use of 75 % RDN along with
25 % N through poultry manure increased the grain and stover yield as well as brix and
sucrose content. Besides, nutrient concentration, uptake, soil enzymatic activity and
available nutrient status also increased. Combined application of chemical fertilizer with
manures and biofertilizers showed an added advantage by improving the yields and
sustaining the fertility in Sweet sorghum. Thus indicating the possibility of substituting
about 25 % organic N fertilizer through poultry manure or vermicompost.
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Keywords
INTEGRATED, NUTRIENT, MANAGEMENT, rabi, SWEET, SORGHUM, PONGAMIA, BASED, AGRISILVICULTURE, SYSTEM