Nitrogen use efficiency of rice as affected by the type of urea fertilizers and soil properties in Burkina Faso
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Date
2015-03-02
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Abstract
The loss of nitrogen (N) can be very high in rice (Oryza sativa L.) fields, particularly
in the irrigated rice cropping systems with very poor water control. Previous studies
have reported low (30%) N use efficiencies (NUE) using broadcast application
method of fertilizer N (Urea) in irrigated cropping systems. This low N use
efficiency is associated with low yields. This thesis is addressing strategies to
increase NUE and rice yields in irrigated system. The effect of urea fertilizer type
(prilled urea and urea supergranule) on rice yield performance was investigated in
five studies. Field and pot experiments were carried out in a pilot irrigated scheme
of Sourou valley located in the north western part of Burkina Faso. The studies were
conducted in 2012 and in 2013. The main objective of the study was to optimize
nitrogen use efficiency of irrigated rice production by reducing losses from rice field.
The amounts of total nitrogen, phosphorus and potassium uptake increased in the rice
plant with the use of urea supergranule compared to prilled urea during the different
rice growth stages. Acid soil recorded higher N, P and K uptake compared to alkaline
soil. Maximum nutrient uptake was observed at flowering stage. Soil total N content
was higher with the use USG in acid soil than alkaline soil. Root development and
the number of tillers increased with the use of USG in acid soil compared to alkaline
soil. The highest and lowest ammonium concentrations in floodwater were recorded
with the use of PU at 26 kg N ha
-1
(2.8 mg l
-1
) and USG at 52 kg N ha
-1
(2.26 mg l
-1
)
in the wet season of 2012. The overall concentration of ammonium in floodwater
was higher with the use of PU (1.34 mg l
-1
) than USG (0.98 mg l
-1
) during the wet
season of 2013.
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The increases in grain yield following urea deep placement with USG were 8 to 18%
relative to broadcasting method with PU. The straw yield increased with the use of
USG relative to PU also ranged from 10 to 27% during the three cropping seasons.
The use of USG with FKR 62N produced the highest numbers of tillers and panicles,
leading to higher yields. The application of USG increased grain N uptake by 3%, P
uptake by 6% and K uptake by 80% over PU in the wet season of 2012. The increase
in grain N, P and K uptake with USG over PU were 25, 16 and 42 %, respectively in
the wet season of 2013. The highest grain N and P uptake was obtained with USG.
The agronomic efficiency (AE) significantly by 39 and 46% increased with USG
application in the two wet seasons. The physiological efficiency (PE) and recovery
efficiency (RE) varied between rice varieties during the three seasons. During the dry
season AE, PE and RE were not significant with the use of urea fertilizers. The
combined effect of USG and phosphorus did not affect rice yield. The increases in
grain yield with phosphorus application relative to the control ranged from 25 -107% during the wet and dry seasons and the highest yield was recorded at 50P. The
increases in AE with USG 1.8 g over USG 2.7 were 48.93% in the wet season of
2012 and 24.43% in the dry season of 2013.
Description
A thesis presented to the Department of Crop and Soil Sciences, Faculty of
Agriculture, College of Agriculture and Natural Resources, Kwame Nkrumah
University of Science and Technology, Kumasi, Ghana, in partial fulfilment of the
requirements for the award of the degree of
Doctor of Philosophy
in
Soil Science