Section 3 (Crop Management)

Ameta and Sharma
cm) intercropped with soybean in 2:2 row ratios followed by wheat. This was significantly superior to the
rest of the intercropping treatments, which was higher by 20.32 per cent over that calculated under the
check plot (62.87 q/ha). Maize equivalent yield significantly increased with increasing level of nitrogen
up to 160 kg N/ha (78.10 q/ha ) however, the B:C ratio declined beyond the level of 100 kg N / ha .Net
returns and B:C ratio analysis indicated that the highest maize equivalent yield (75.65 q/ha) with the
maximum net returns of Rs. 23,670 / ha having a B:C ratio of 1.99 was calculated when maize in paired
rows was intercropped with soybean in 2:2 row ratios, followed by wheat. Blackgram intercropping in a
similar fashion was the next best treatment (Rs. 22,496 /ha) in sustaining productivity of wheat as
compared to the check (Rs.19,675 /ha ). These results are in conformity with the findings of Shah et al.,
1991 and Das and Mathur 1980.
Nutrient studies
Organic corbon contents varied with different inter-cropping treatments (Table-3). After completion
of the study the check plot, having pure maize-wheat rotation, showed a decline in soil organic corbon of
3.84%, while blackgram and soybean inter-cropping with maize in paired rows in 2:2 row ratio followed
by wheat analyzed increased content of organic corbon in soil as 0.65 and 0.67%, respectively, compared
to initial values of 0.52%. Total nitrogen content of soil also increased with increasing level of nitrogen
(Table-4) in all the intercropping treatments. The highest total nitrogen (1380 kg/ha) was computed under
maize+soybean (paired rows in 2:2 row ratios (30/90cm)) wheat treatment with net positive N balance of
132 kg/ha under 160 kg N/ha level. This increase in N availability might be due to the decaying of
nodules of legumes. Similar findings were reported by Singh and Awasthi, (1982) and Singh and Bajpai,
(1991). It is evident from the data pertaining to net nitrogen balance (Table-4) that inter-cropping with
soybean/blackgram even at lowest N level (i.e. 40 kg N/ha) had a positive net soil nitrogen balance which
indicates that legume intercrops sustain the maize-wheat production even at low level of nitrogen
application.
Contribution of atmospheric N fixation was computed by different legume intercrops during three
years of experimentation, which varied from 111.67 to 170.67 kg/ha (Table-5). Soybean intercropping
with maize in paired rows in 2:2 row ratios followed by wheat contributed to about 170.67 kg N/ha in
three years of study. Quantity of nitrogen fixed by legumes serves as an input for subsequent crops
depending upon the quantum fixed. These results are in confirmation with Aardesna et al. (1993), who
reported symbiotic nitrogen fixation ranging from 20-300 kg N/ha by Rhizobium-legume symbiotic
association. Thus, intercropping with these legume crops during the rainy season produced highest yields
and maintained soil health.
Conclusion
Maize in paired rows (30/90 cm) with soybean in 2:2 row followed by wheat gives the highest net
return of Rs23,670/ha having a B:C ratio of 1.99 and increased contents of organic carbon in soil as 0.67
percent compared to initial values of 0.52 per cent. Nitrogen balance under different intercropping
treatments was worked out .The highest buildup of soil N (i.e.132 kg N/ha) was obtained under this
intercropping treatment. Contribution of intercrops to fix atmospheric nitrogen during three years of
experimentation was computed, which varied from 109 to 172 kg/ha. This treatment contributed the
highest atmospheric nitrogen in the soil.
Thus, soybean intercropping with maize in paired rows in 2:2 row ratios followed by wheat was
found to be the most sustainable for sub-humid southern zone of Rajasthan, India.
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