| dc.description.abstract | Persistent droughts, soil infertility and reduced land sizes are major limitations to agricultural
productivity in Migori County. Intercropping drought tolerant legumes with cereals such as
sorghum and groundnuts is one of the coping strategies that have been proposed but the
effectiveness of these systems particularly under various sources of nitrogen (N) is not clear.
A study was therefore conducted at Nyabisawa and Piny Oyie in Migori County during the
long rains of 2019 to establish the effect of inorganic and organic N sources on the yield and
yield components, land equivalent ratio (LER) and agronomic efficiency (AE) of sorghum -
groundnut cropping systems. A Randomised Complete Block Design (RCBD) replicated
thrice was used. Treatments included: sole sorghum, sole groundnut and sorghum - groundnut
intercrop supplied with N from two sources, that is, organic (farmyard manure (FYM)) and
inorganic (urea). Crops in the sole sorghum and sorghum - groundnut intercrop received N at
rates of 40 and 80 kg/ha from each source and 40 kg N/ha provided by urea combined with
FYM in equal amounts (20 kg N/ha from each source). Sole groundnuts received at 20 kg N/ha
from each source and 20 kg N/ha provided by urea combined with FYM in equal proportions
(10 kg N/ha from each source). There was a zero N input treatment for each cropping system.
Sowing was at the onset of the rains and harvesting done at physiological maturity. The
effectiveness of intercropping was determined using LER while the agronomic efficiency was
determined using AE. All data were subjected to analysis of variance and the significant
treatment means were separated using LSD (p ≤ 0.05.) Synergism was observed where use of
40 kg N/ha from combined sources significantly increased the sole sorghum plant heights
above the unfertilized sole sorghum and also gave the tallest plants at 4, 6 and 8 WAP and the
highest sorghum grain and stover yields at Nyabisawa and Piny Oyie. In the intercrop however,
the use of N from urea at 40 and 80 kg N/ha from urea and 80 kg N/ha from FYM became
important considering the higher demand for minimal resources available in the intercrop. The
unfertilized intercropped sorghum had the shortest plants and lowest grain and stover yields in
both sites due to the N deficiency which had not been managed thus the need to supply N to
the crops so as to improve their yields. In groundnuts, the yields of sole groundnuts to which
20 kg N/ha from urea was applied were significantly superior compared to those supplied with
20 kg N/ha from FYM. Only FYM applied at 20 kg N/ha on sole groundnuts significantly
increased the groundnut pods per plant and the biomass yields above the unfertilized sole
groundnuts at Nyabisawa. Intercropping was beneficial (LER>1) where 0 kg N/ha, 80 kg N/ha
from urea and 80 kg N/ha from FYM were applied. The AEs decreased with increasing N rates
in the sole sorghum, while in the intercrop, they increased with increasing N rates. This was
observed where sole sorghum that received 40 kg N/ha from urea and the combined sources
had significantly higher AEs than those that received 80 kg N/ha from urea and FYM at
Nyabisawa and those that received 80 kg N/ha from FYM at Piny Oyie. In the intercrop, it was
noted that where 80 kg N/ha from urea and FYM was supplied, the AEs were significantly
higher than those which received 40 kg N/ha from combined sources at Nyabisawa and Piny
Oyie. In sole groundnuts however 20 kg N/ha from urea had a significantly higher agronomic
efficiency compared to all the other treatments since the crops needed N before they were well
established to start fixing their own N. In conclusion, the application of 40 kg N ha–1
from
combined sources in sole sorghum, 20 kg N ha–1
from urea in sole groundnuts and either 80
kg N ha–1
from urea or FYM on the intercropped sorghum and groundnuts gave the best yields
and could be recommended to farmers for adoption especially when production is done under
similar conditions | en_US |
