MSc

The study entitled “Nutrient budgeting in rice based farming system” was
undertaken at College of Agriculture, Vellayani during 2015 –’17.The main
objectives were to study the effect of component crops on soil nutrient status, to
characterize and study the effect of trench silt on the performance of rice and to work
out the nutrient balance sheet of the rice based farming systems.
The field experiment was conducted as a part of an ongoing experiment under
the AICRP on Integrated Farming Systems (ICAR), at the Integrated Farming System
Research Station (IFSRS), Karamana, Thiruvananthapuram. The experiment was laid
out in randomised block design with seven treatments, replicated thrice. The
treatments
comprised
seven
rice
[T1 : rice-rice-fallow; T2 : rice-rice-amaranthus;
based
farming
systems
T3 : rice-rice-culinary melon;
T4 : rice-rice-fodder cowpea; T5 : (rice + fish)-(rice + fish)-(amaranthus + fish); T6 :
(rice + fish)-(rice + fish)-(culinary melon + fish); T7 : (rice + fish)-(rice + fish)-
(fodder cowpea + fish). The present study was undertaken during the summer 2015-
’16 (February to May) and Virippu 2016-’17 (June to October) seasons. The varieties
of rice, amaranthus, culinary melon and fodder cowpea were Uma, Arun, Vellayani
local and Aiswarya respectively. The fishes viz., catla (Catla catla) and rohu (Labio
rohita) were introduced into the trenches(6m x 3m x 1m) after transplanting Virippu
crop and were harvested after the summer crop. After summer season, the trenches
were desilted and the silt was added to the respective plots, before raising Virippu
rice. The soil nutrient status of Mundakan season 2015-‘16 was also taken into
account for working out the nutrient balance sheet of the systems.
In summer, fodder cowpea grown as a sole crop recorded the highest yield
(23703 kg ha-1) and total dry matter production. Among the treatments integrated
with fish, culinary melon + fish (T6) gave higher yield compared to amaranthus and
fodder cowpea. The productivity of amaranthus and culinary melon was found to
increase to the tune of 208.80 per cent and 256.43 per cent respectively,with fish
integration. Rice equivalent yield was significantly higher (13.57 t ha-1) for culinary
melon + fish (T6).
After the summer season, the trench water and trench silt were analysed. The
trench water had near neutral pH (7.18) and had higher contents of N, P and K.
Substantial quantity of trench silt (20.93 t per 0.5 ha on dry weight basis) was added
to the plots with fish integration and incorporated, before raising the Virippu rice.
Trench silt was found to be clayey in texture with lower bulk density (0.78 Mg m-3),
higher water holding capacity (47.38 %) and rich in N, K, S and Zn.
In Virippu rice,grain weight panicle-1(4.08 g), total number of grains panicle-1
(159.80),
filled grains panicle-1 (144.35) and grain yield (6.62 t ha-1) were
significantly higher in T7 (rice + fish succeeding fodder cowpea + fish). It was on a
par with T5 (rice + fish succeeding amaranthus + fish) and T6(rice + fish succeeding
culinary melon + fish). Sterility percentage decreased with fish integration and it was
the lowest (5.69 %) in T5and remained at par with T6.In general, productivity of rice
was 15.56 per cent higher with fish integration.
Among the summer crops, the uptake of N, P, K, Mg, S, B and Zn was
significantly higher in amaranthus and culinary melon integrated with fish as
compared to the respective sole crops. While, fodder cowpea grown as sole crop
recorded the highest content and uptake of Ca. In Virippu rice, significantly higher
uptake of nitrogen and phosphorus was observed in T7 (rice+fish succeeding fodder
cowpea+fish).
Soil chemical properties were analysed before and after each component crop.
Soil reaction (pH) was significantly higher (less acidic) in T5 (rice+fish)-(rice+fish)-
(amaranthus+fish). In general, treatments with fish integration recorded higher soil
pH compared to treatments without fish. The treatment T1 (rice-rice-fallow) recorded
the highest electrical conductivity after Mundakan and summer seasons and T2 (rice-
rice-amaranthus) recorded the same after Virippu season. Organic carbon content of
soil was higher in T1 (rice-rice-fallow) before and after summer season. The highest
soil available N was recorded in T2 (rice-rice-amaranthus) before and after summer
and in T5after Virippu seasons. Available P was the highest in T5 before and after
summer crop. Significantly higher available K content was observed in T5 before
summer crop. Exchangeable Ca, exchangeable Mg, S and Zn were found highest in
T5. Rice + fish integration (T5, T6and T7) resulted in significantly higher B content in
soil. In general, fish integration was observed to improve the soil nutrient status.
Nitrogen balance was positive after summer with fodder cowpea irrespective
of fish integration. A positive N balance was recorded in T1 (rice-rice-fallow) after
the Virippu season. The P balance was observed to be negative in all the treatments
after summer and Virippu seasons, except in T1 (rice-rice-fallow) after summer. Fish
integration resulted in a positive balance for K after summer in T5, T6 and T7. All the
treatments recorded a positive balance for K and Mg after the Virippu season. After
summer, T1, T4 and T7 recorded positive balance, while after Virippu all the
treatments except T2recorded positive balance for Ca. Balance sheet was negative for
S and Zn. A varying trend was observed for B.
The present study revealed that integrating fish in rice based farming systems
resulted in higher soil residual nutrient status (P, Ca, Mg, S and Zn). The trench silt
had low bulk density, high water holding capacity and was rich in N, K, S and Zn.
Fish integration and consequent trench silt incorporation increased the rice yield by
15.56 per cent as compared to sole crop of rice. Fodder cowpea grown as component
crop in rice based farming system resulted in positive balance for N, K and Ca.
Integration of fish resulted in positive balance for K. The balance sheet of P, Mg, S
and Zn was observed to be negative.
സംഗ്രഹം
നെല്ലധിഷ്ടിത
ബജറ്റിങ്എന്ന
കൃഷി
സമ്പ്രദായങ്ങളില്‍
വിഷയനെ
സർവകൊാാെയുന
സംബന്ധിച്ച
ധധനെതയില്‍
മണ്ണിനെ
ഒരു
ഠെം
തിരുവെന്ത ുരം
പ ാഷക
പകരള
മൂെക
The study entitled “Nutrient budgeting in rice based farming system” was
undertaken at College of Agriculture, Vellayani during 2015 –’17.The main
objectives were to study the effect of component crops on soil nutrient status, to
characterize and study the effect of trench silt on the performance of rice and to work
out the nutrient balance sheet of the rice based farming systems.
The field experiment was conducted as a part of an ongoing experiment under
the AICRP on Integrated Farming Systems (ICAR), at the Integrated Farming System
Research Station (IFSRS), Karamana, Thiruvananthapuram. The experiment was laid
out in randomised block design with seven treatments, replicated thrice. The
treatments
comprised
seven
rice
[T1 : rice-rice-fallow; T2 : rice-rice-amaranthus;
based
farming
systems
T3 : rice-rice-culinary melon;
T4 : rice-rice-fodder cowpea; T5 : (rice + fish)-(rice + fish)-(amaranthus + fish); T6 :
(rice + fish)-(rice + fish)-(culinary melon + fish); T7 : (rice + fish)-(rice + fish)-
(fodder cowpea + fish). The present study was undertaken during the summer 2015-
’16 (February to May) and Virippu 2016-’17 (June to October) seasons. The varieties
of rice, amaranthus, culinary melon and fodder cowpea were Uma, Arun, Vellayani
local and Aiswarya respectively. The fishes viz., catla (Catla catla) and rohu (Labio
rohita) were introduced into the trenches(6m x 3m x 1m) after transplanting Virippu
crop and were harvested after the summer crop. After summer season, the trenches
were desilted and the silt was added to the respective plots, before raising Virippu
rice. The soil nutrient status of Mundakan season 2015-‘16 was also taken into
account for working out the nutrient balance sheet of the systems.
In summer, fodder cowpea grown as a sole crop recorded the highest yield
(23703 kg ha-1) and total dry matter production. Among the treatments integrated
with fish, culinary melon + fish (T6) gave higher yield compared to amaranthus and
fodder cowpea. The productivity of amaranthus and culinary melon was found to
increase to the tune of 208.80 per cent and 256.43 per cent respectively,with fish
integration. Rice equivalent yield was significantly higher (13.57 t ha-1) for culinary
melon + fish (T6).
After the summer season, the trench water and trench silt were analysed. The
trench water had near neutral pH (7.18) and had higher contents of N, P and K.
Substantial quantity of trench silt (20.93 t per 0.5 ha on dry weight basis) was added
to the plots with fish integration and incorporated, before raising the Virippu rice.
Trench silt was found to be clayey in texture with lower bulk density (0.78 Mg m-3),
higher water holding capacity (47.38 %) and rich in N, K, S and Zn.
In Virippu rice,grain weight panicle-1(4.08 g), total number of grains panicle-1
(159.80),
filled grains panicle-1 (144.35) and grain yield (6.62 t ha-1) were
significantly higher in T7 (rice + fish succeeding fodder cowpea + fish). It was on a
par with T5 (rice + fish succeeding amaranthus + fish) and T6(rice + fish succeeding
culinary melon + fish). Sterility percentage decreased with fish integration and it was
the lowest (5.69 %) in T5and remained at par with T6.In general, productivity of rice
was 15.56 per cent higher with fish integration.
Among the summer crops, the uptake of N, P, K, Mg, S, B and Zn was
significantly higher in amaranthus and culinary melon integrated with fish as
compared to the respective sole crops. While, fodder cowpea grown as sole crop
recorded the highest content and uptake of Ca. In Virippu rice, significantly higher
uptake of nitrogen and phosphorus was observed in T7 (rice+fish succeeding fodder
cowpea+fish).
Soil chemical properties were analysed before and after each component crop.
Soil reaction (pH) was significantly higher (less acidic) in T5 (rice+fish)-(rice+fish)-
(amaranthus+fish). In general, treatments with fish integration recorded higher soil
pH compared to treatments without fish. The treatment T1 (rice-rice-fallow) recorded
the highest electrical conductivity after Mundakan and summer seasons and T2 (rice-
rice-amaranthus) recorded the same after Virippu season. Organic carbon content of
soil was higher in T1 (rice-rice-fallow) before and after summer season. The highest
soil available N was recorded in T2 (rice-rice-amaranthus) before and after summer
and in T5after Virippu seasons. Available P was the highest in T5 before and after
summer crop. Significantly higher available K content was observed in T5 before
summer crop. Exchangeable Ca, exchangeable Mg, S and Zn were found highest in
T5. Rice + fish integration (T5, T6and T7) resulted in significantly higher B content in
soil. In general, fish integration was observed to improve the soil nutrient status.
Nitrogen balance was positive after summer with fodder cowpea irrespective
of fish integration. A positive N balance was recorded in T1 (rice-rice-fallow) after
the Virippu season. The P balance was observed to be negative in all the treatments
after summer and Virippu seasons, except in T1 (rice-rice-fallow) after summer. Fish
integration resulted in a positive balance for K after summer in T5, T6 and T7. All the
treatments recorded a positive balance for K and Mg after the Virippu season. After
summer, T1, T4 and T7 recorded positive balance, while after Virippu all the
treatments except T2recorded positive balance for Ca. Balance sheet was negative for
S and Zn. A varying trend was observed for B.
The present study revealed that integrating fish in rice based farming systems
resulted in higher soil residual nutrient status (P, Ca, Mg, S and Zn). The trench silt
had low bulk density, high water holding capacity and was rich in N, K, S and Zn.
Fish integration and consequent trench silt incorporation increased the rice yield by
15.56 per cent as compared to sole crop of rice. Fodder cowpea grown as component
crop in rice based farming system resulted in positive balance for N, K and Ca.
Integration of fish resulted in positive balance for K. The balance sheet of P, Mg, S
and Zn was observed to be negative.