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EFFECTS OF SALINE WATER AND IRRIGATION INTERVAL ON SOYBEAN (GLYCINE MAX) YIELD AND ALTERING SOIL PHYSICO-CHEMICAL PROPERTIES
(Hawassa University, 2018-10-26) ATALEL AWOKE
The declining availability of fresh water has become a worldwide problem, which maintains
the development of alternative, secondary quality water resources for agricultural use. Several
studies recommend that the need of attention for selected crops that can tolerate water and
salinity stresses when saline water is used for irrigation. In this study, the effects of different
irrigation intervals and salinity levels of irrigation water on Soybean yield and their impacts
on soil physico-chemical properties were investigated using three irrigation intervals (I1
=3days, I2= 4days and I3= 5 days) with four salinity levels (S1= 4dS m-1
, 5dS m-1
and 6 dS m-
1
) in a factorial combination using CRD with three replications. The result showed that
salinity, irrigation interval and their interaction had shown highly significance effects
(p<0.001) on number of pod per plant, number of seed per plant and grain yield of Soybean.
The highest number of pod number (88.33), grain yield (2.31ton/ha) and number of seed per
plant (172.33) was recorded from Soybean which was irrigated with the first salinity level, i.e.
fresh water (S1) with irrigation interval of (3 days), S1I1;while the lowest pod number per plant
(6.67), number of seed per plant (12.67) and minimum grain yield (0.034 ton/ha) were
obtained from Soybean irrigated by salinity level four (S4) with 5 days irrigation interval
(S4I3).Statistical analysis showed that salinity ,irrigation interval and their interaction showed
highly significance effects (p<0.001)on electrical conductivity of soil. Irrigation with highest
salinity level (S4) with five days of irrigation interval resulted in the salt accumulation in the
root zone from 0.41 μS m
-1
(before sowing) up to 13.73 μS/cm at the end of growing period
and exchangeable Sodium of 0.2 cmol/Kg was found before sowing while 0.82cmol/kg was
found after harvesting. Therefore, based on soil salinity and crop yield, irrigation interval of 3
days at lower levels of irrigation water salinities (up to 3 dS m-1
) is suitable for soybean
production in the study area. The study also showed that salinity and irrigation interval
significantly affected the soil nutrients (p< 0.001) despite their interaction were not
significantly affected on soil nutrients. Increasing the concentration of salt in irrigation water
reduce availability of nutrients in the soil. Soil which was irrigated by salinity level four
(S4=6dS/m) had lowest Organic Matter, Organic Carbon, Nitrogen (N), Phosphorus (P) and
Potassium (K) content. Highest Organic Matter, Organic Carbon, N and P content were
observed at soils which were irrigated by fresh water. This indicates that there is a need for
giving attention for management of soil besides achieving Soybean yield production when
saline water is used for irrigation
EVALUATING THE PERFORMANCE OF AQUACROP MODEL IN SIMULATING THE PRODUCTIVITY OF POTATO (Solanum tuberosum L.) CROP UNDER VARIOUS WATER LEVELS AT DEBRE BIRHAN, AMHARA REGIONAL STATE, ETHIOPIA
(Hawassa University, 2019-10-22) TSEGAYE GETACHEW MENGISTU
Agricultural sector face the challenge to produce more yield with less water. In this
regard, simulation models are basic tools in evaluating the effect of water on crop
production. To address this need, FAO has developed yield responses to water model
named AquaCrop, which simulates attainable yields of the major field and vegetable
crops from their physiological and agronomic background perspective at farm level. The
aim of this study was to evaluate the AquaCrop model performance on potato crop
growth parameters under various water levels at Debre Birhan, Ethiopia. The AquaCrop
is a user-friendly, easy to apply, accurate and robust model, and it addresses conditions
where water is a key limiting factor for crop production. The experiment was arranged
with Randomized Complete Block Design, with four replications under different water
levels 100%, 85%, 70% and 55 % of crop water requirement of potato, which were
simulated by the AquaCrop model. The results indicated that the simulated amount of
irrigation water for 100% water level was 377.2 mm of water depth in growing season.
The growth parameter and tuber yield were significant differences among the water
levels at p < 0.05. The fresh potato tuber yield ranges from 35.25 ton/ha to 44.37 ton/ha
was obtained in 55% and 100% water levels respectively. The water productivity ranges
from 11.59 kg/m3
to 12.67 kg/m
3
was obtained in 100%and 55% water level respectively.
Concerning its performance, the AquaCrop model simulated very well in the canopy
cover, dry aboveground and tuber biomass and soil water content of the potato crop. The
statistical indicators; Nash-Sutcliffe efficiency (NSE), Normalized Root mean square
error (NRMSE) index of agreement (d) and Coefficient of determination (R
2
) showed
very well to excellent efficiency observed on dry aboveground and tuber biomass, there
values were found to be in the ranges of 0.78 to 0.94, 35.50 to 16.30, 0.96 to 0.99 and
0.98 to 0.96 respectively. However, for soil water content before irrigation, which was
found to be poor ranges 0.00 to -0.63, 10.2 to 10.8, 0.78 to 0.51, 0.45 to 0.03 were
observed respectively.in the above order. From the results of the study can conclude in
two scenarios: first, in case of water scarce area, it may be more profitable for a
farmer to maximize crop water productivity instead of maximizing the harvest per unit
of land. The saved water can be used to irrigate extra units of land. Second, in case of
no water scarce area, it may be more profitable to maximize the yield harvest than
crop water productivity. Under the first scenario farmers should adopt 70% of crop
water requirement with a 10-days interval, which 16.65% saved water with 10.1% yield
penalty over 100%. On the other hand, they should adopt 100% of crop water
requirement within 10-days interval In the case of no water scarce area. The future studies
shall consider various other stresses such as soil fertility and mulching
CARBON NANOTUBES
(USA, 1996) MORINUBO END0; SUM10 IIJIMA; MILDRED S. DRESSELHAUS
A Laboratory Course in Nanoscience and Nanotechnology
(Taylor & Francis, 2015) Gérrard Eddy Jai Poinern
Modern industrial microbiology and bitechnology
(USA, 2007) Nduka Okafor