PhD

An investigation was carried out during 1995-96 and 1996-97 at the Instructional
Farm attached to College of Agriculture, Vellayani to study the efficacy of different levels of
N applications (200, 250 and 300 kg N ha") in different ratios of organic - chemical N
substitutions (l : 1, 1:2 or 2: 1) at different frequencies (F I - full quantity of organic source as
basal, F2 - organic source at basal and at 40th and 70th DAS, F3 - organic source as basal
+ fortnightly equal splits and chemical N source as basal + fortnightly intervals in equal
splits in all the frequencies) of application. Two different organic sources ie. farm yard
manure and poultry manure were used in two simultaneous experiments viz. Experiment I
and 11. The experiments were separately and simultaneously laid out as confounded 33
design in 9 plot blocks with 2 replications, confounding LR2F in RI and LRF2 in R 11.
Higher levels ofN nutrition was found to reduce days taken to flower in farm yard
manure applied trial while sex ratio was narrowed at 90 DAS in poultry manure applied
experiment. Higher jassid population was noticed at 60 DAS when higher levels ofN
was supplied predominantly through organic source as farm yard manure. Fungal leaf spot
infestation was higher with the application of200 kg N at 90 DAS and was also more with
split applications of both farm yard manure and chemical N source at early stages of growth.
Full basal application of poultry manure was found to promote the per hectare
yield of fruits, fruit yield planr I and number of fruits planr I compared to its split applications.
When highest level ofN (300 kg) was supplied through 2: 1 ratio of organic - chemical N
substitution using poultry manure as organic source, it effectively increased the fruit yield
and number of fruits plant".

2
Shelf life of fruits at room temperature was more when nutrient N was supplied
through 2: 1 ratio of organic - chemical N substitution using farm yard manure or poultry
manure as an organic source. When N level was increased beyond 200 kg, shelf life of
fruits at room temperature slightly decreased even when it was predominantly supplied
through organic source of farm yard manure or poultry manure. Similar trend was noticed
at refiigeratory condition too.
Nitrogen nutrition showed depressing effect on ascorbic acid or vitamin-C content
of fruits in Experiment I. Iron content in fruits was more with the application of 200 or
300 kg N level in Experiment ll. When 300 kg N was applied through a major source of
poultry manure (2: 1 ratio) it produced higher iron content in fruits.
Higher nitrogen levels or nitrogen nutrition through 2: 1 ratio of substitution promoted
the soil bacterial population in both Experiment I and II. Full basal application of farm yard
manure or poultry manure favourably influenced the soil bacterial population. Nitrogen
nutrition showed depressing effect on fungal population of soil in Experiment I while it
stimulated the fungal growth in Experiment 11. Soil actinomycetes population was higher
with 2: 1 substitution ratio using farm yard manure as organic source ofN.
When farm yard manure or poultry manure as organic source was used in equal
or higher proportion with chemical N source, it showed moderating effect on the soil
acidity. Full basal application of farm yard manure also enhanced the soil pH from the
acidic range and the organic carbon content.
Application of higher levels ofN increased the net loss ofN, P and K of soil in
both the Experiment I and H. Net loss ofN was higher with 1:2 ratio ofN substitution or
few or more split applications of organic source (farm yard manure) in Experiment 1. Net
loss of nutrients was moderated during the second year of field experimentation. Nitrogen

3
nutrition in 1:2 ratio of substitution enhanced the net loss ofN in Experiment H. Nitrogen
nutrition through 2: 1 ratio ofN substitution or basal + 2 split doses of farm yard manure
increased the net loss of P in soil. The net loss of K in soil was more when farm yard
manure and chemical N sources were applied in 2: 1 or 1: 1 ratio of substitution. Net gain of
K was observed in Experiment H, when chemical N source was substituted in higher
proportion compared to poultry manure or when full dose of poultry manure was applied
as basal dressing.
Higher levels ofN application have resulted in negative net energy returns or
energy loss in both the experiments. The 1: 1 or 1 :2 ratio ofN substitution caused higher
net energy losses in Experiment I while split applications of poultry manure resulted in more
energy loss in Experiment H. Total energy output was higher with full basal application of
poultry manure in Experiment I. Energy ratios registered a negative value and was higher
with low level ofN application in Experiment I and II.
Higher gross returns were obtained when full quantity of poultry manure was applied
as basal dose in Experiment 11. Application of300 kg N through 2: 1 ratio of organic-
chemical N substitution registered higher gross returns in Experiment II. Net returns was
higher when 200 kg N ha! was applied. Increasing N level beyond 200 kg was not
economic in Experiment I using farm yard manure as organic source. When full quantity of
poultry manure was applied completely as basal dose, higher net returns was obtained in
Experiment H. Benefit-cost ratio decreased when N level was enhanced beyond 200 kg
ha' in Experiment I. Higher benefit - cost ratio was recorded when poultry manure was
applied in full dose as basal dressing.
Study revealed the favourable influence of organic sources; farm yard manure and
poultry manure on fruit quality, shelf life and soil properties. The suitability of poultry manure
as organic source for vegetable cultivation was also established by this study.