This study examined the effect of deficit irrigation on soil properties, physiology, and nutrient assimilation of sweet peppers. Three irrigation treatments were used: T1 (100% crop water requirement), T2 (90% CWR), and T3 (80% CWR). The results showed that higher irrigation amounts (T1) produced lower bulk density and higher porosity compared to the deficit treatments. Dry matter accumulation and harvest index decreased with greater water deficits. Nitrogen, phosphorus, and potassium uptake by the peppers also decreased as the irrigation amounts decreased. While deficit irrigation affected soil physical properties, the effects were not significant. However, available soil moisture had a strong influence on nutrient uptake by the crops.

1. TOPIC
EFFECT OF DEFICIT IRRIGATION ON SOIL PROPERTIES,
PHYSIOLOGY AND NUTRIENT ASSIMLATION OF SWEET
PEPPER (Capsicum annuum)
BY
TABITHA MENSAH

2. INTRODUCTION
 Water supplies are limited worldwide (Postel, 1998) and there is an
urgent need to identify and adopt better irrigation management
strategies.
 Low moisture in the soil may however lead to problems of reduced
growth rate, metabolic activities, development and yield of crops.
 Low soil moisture could also result in total loss of a farmer’s whole
crop or make his crops vulnerable to both biotic and abiotic
complications (Ware and McCollum, 1975).

3. INTRODUCTION CONT’D
 Deficit irrigation, is a practice of reducing the amount of water
supplied to a crop or reducing the frequency of water application.
 It ensures optimum yield in times of drought or make proper use of
irrigation water.
 The application of less water reduces the leaching effects of
nutrients from the root-zone and agrochemicals and the groundwater
quality is preserved (Pandey et al., 2000)..

4. BENEFITS OF SWEET PEPPER
SWEET
PEPPER
Beautification, taste, flavour
Vitamins(thiamin
e, carotene, B12)
Spices, sauce, pickles
Phytochemical
properties

5. PROBLEM STATEMENT
 Relative abundance or scarcity of water as well as the lack of
irrigation knowledge leads to over irrigation or under irrigation.
 This results in leaching of plant nutrients, saturation of soil to create
anaerobic conditions which can result in root damage, reduced root
respiration, and lime hydrolysis as well as denitrification of nitrate
fertilizers.
 Therefore, there is the need to consider measuring the amount of
water applied to crop like sweet pepper which has an extensive
shallow root system, and is susceptible to water logging.

6. OBJECTIVE
 General objective
To examine the effect of deficit irrigation on soil properties,
physiology and nutrient uptake of sweet pepper.
Specific objective
 To assess the effect of deficit irrigation on the harvest index and dry
matter accumulation.
 To assess the effect of nitrogen, phosphorus, potassium uptake by
sweet pepper.
 To assess the effect of deficit irrigation on soil physical properties.

7. JUSTIFICATION
 Several researches have been carried out on deficit irrigation with
resulting indicating 10-15% reduction of crop water requirement had
no significant effect on the yield.
 The interest of the research was to investigate the effect of deficit
irrigation on soil physical & chemical properties and physiology of
sweet pepper which have a direct effect of the yield.

8. STUDY AREA
The study was conducted at the engineering field of the School of
Agriculture Teaching and Research Farm at University of Cape Coast.
AREA FEATURES
 Annual temperature of 23.2-33.2 ºC with an annual mean of 27.6 ºc
 Relative humidity is 81.3-84.4% (Owusu-Sekyere et al 2011).
 The annual rainfall is between 650 and 1100 mm (Alhassan, 2009).

9. EXPERIMENTAL DESIGN
Design
Completely Randomized Block Design (CRBD) with three (3)
treatments (T1-T3) and three (3) replications (R1- R3). Each
replication had 4 (four) plants.
Treatment
T1, 100% of CWR; T2, 90% of CWR; T3, and 80% of CWR.
Planting
Sweet pepper seeds were nursed, and the healthy seedlings were
transplanted into the plastic pots under a rain shed on.

10. DATA PARAMETERS
Data was collected on the following parameters
 Soil physical properties ; bulk density, particle density and
porosity
 Soil chemical properties ; Nitrogen %, potassium and
phosphorus content
 Vegetative parameters ; dry matter accumulation and harvest
index

11. DRY MATTER ACCUMULATION
 Fresh leaves from the top, middle and down part of data plants
randomly selected and weighed.
 Samples were oven-dried at 105 ºC to constant weight to determine
their total dry weight.
 Dm= Total dry weight of sample ×100
Total fresh weight of sample
(Patel & Rajput, 2013)

12. HARVEST INDEX
 Harvest index was calculated by dividing total dry weight of fruit by
total dry weight of plant.

13. BULK DENSITY
Bulk density of soil was determined using the method as described by
(McKenzie et al., 2004).
Bulk density (g/cm3) = (𝐷𝑟𝑦 𝑠𝑜𝑖𝑙 𝑤𝑒𝑖𝑔ℎ𝑡 (𝑔))/(𝑆𝑜𝑖𝑙 𝑣𝑜𝑙𝑢𝑚𝑒 (𝑐𝑚3))
Dry soil weight (g) = W2 – W1
Soil volume (cm3) = 3.14 x r2 x ring height.

14. PARTICLE DENSITY
Particle density was calculated as follows;
 Volume of soil solids = final volume of soil – initial water volume
(50ml)
 Particle density = oven-dry soil weight / volume of soil solids

15. POROSITY
 Porosity of each sample was calculated by finding the ratio of bulk
density to particle density and multiplying by 100 to give the %
solid space. 100 were then subtracted from the % solid space to
obtain the porosity for each sample.
 % solid space = (bulk density / particle density) x 100
 % porosity = 100 - (% solid space)

16. PERCENTAGE NITROGEN
 Micro-Kjedahl method was used for nitrogen determination.
 Steps involved in nitrogen determination are;
 Digestion, Distillation and Titration
 𝑁 (%) = (𝑆−𝐵)𝑋 𝑆𝑂𝐿𝑈𝑇𝐼𝑂𝑁 𝑉𝑂𝐿𝑈𝑀𝐸)
(100 𝑋 𝐴𝐿𝐼𝐺𝑈𝑂𝑇 𝑋 𝑆𝐴𝑀𝑃𝐿𝐸 𝑊𝐸𝐼𝐺𝐻𝑇)
Where
 S - sample titre value
 B – Blank titre value

17. PHOSPHORUS DETERMINATION
 Bray No 1 method (with Ascorbic Acid) was used.

18. POTASSIUM CONT’D
 Flame photometry was used to determine potassium.

19. STATISTICAL ANALYSIS
 The various results obtained were subjected to the analysis of
variance (ANOVA) using Genstat statistical software.
 Mean comparisons were done using least significance difference
test at a probability level of 5%.

20. RESULTS
Treatment Bulk density (g/cm3) Particle density (g/cm3) Porosity %
T1 1.333 a 2.530 a 45.53 a
T2 1.357 b 2.610 b 47.83 b
T3 1.387 c 2.630 b 49.30 b
Lsd0.05

21. Treatment Harvest index Dry matter accumulated
T1 1.333 a 733.7 a
T2 1.357 b 786.8 ab
T3 1.387 c 811.3 c
Lsd0.05

22. EFFECT OF DEFICIT IRRIGATION ON NITROGEN
UPTAKE
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
NB NA NB NA NB NA
T1 T2 T3
(Nitrogenlevel%)
Source; field data 2015

23. EFFECT OF DEFICIT IRRIGATION ON POTASSIUM
UPTAKE
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
KB KA KB KA KB KA
T1 T2 T3
Potassiumlevels(KCmol/kg
Source; field data 2015

24. EFFECT OF DEFICIT IRRIGATION ON PHOSPHORUS
UPTAKE
0
5
10
15
20
25
30
35
40
45
PB PA PB PA PB PA
T1 T2 T3
Phosphoruslevels(Pgp/g)
Source; field data 2015

25. CONCLUSION
From the results on the study it could be concluded that
 Although deficit irrigation affects soil physical properties but its effect
is not significant. However increasing water deficit has increasing
effect on soil physical properties.
 Also the higher available moisture content the higher the rate of
nutrient uptake. However excessive application of water could lead to
leaching effect on certain soil nutrients.

26. RECOMMENDATION
From the study it could be recommended that;
 A comprehensive study should be carried out on the effect of deficit
irrigation on other micro nutrients uptake in the soil (Ca, Mg)
 Also a study on the salinity rate of soil under deficit irrigation must be
carried.
 Also other varying levels of water deficit on soil physiochemical
properties can be researched.

27. END OF PRESENTATION
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