A field experiment was carried out on a newly reclaimed
calcareous soil with sandy loam texture class at a Private Farm adjacent
to Alexandria road (km 52), and cultivated with tomato plants
(Lycopersicon esculentum) under two irrigation systems (furrow and
drip) during growing season of 2005. Fertilization methods were carried
out as soil and fertigation applications. The used fertilizers were urea
(46% N) and mono-potassium phosphate (15% P205 and 38% K2O), with
rates of 100 kg N fed-1, 40 kg P2O5 fed-1 and 48 kg K2O fed-1. This work
aims to study the effects of irrigation and fertilization methods on tomato
yield and fruit quality, with special reference to NPK fertilizers use
efficiency.
At the elongation stage (60 days after transplanting), some
selected plants were taken to determine some vegetative growth
parameters, i.e., plant height, dry weight, leaf area index, number of
flowers per plant and the chlorophyll concentration (a and b) as well as
N, P and K uptake by plants. Soil samples were also taken at different
depths (0-15, 15-30, 30-45 and 45-60 cm) to determine available N, P
and K. In addition, at harvest (90 days after transplanting) tomato yield
and the fruit quality parameters (firmness, total soluble solids, titrable
acidity, vitamin C and total sugar) were identified.
The obtained results reveal that experimental soil is classified as
Typic Haplocalcids, coarse loamy, mixed, thermic. According to a
parametric evaluation system, it could be evaluated as moderately
suitable (S2s1s3s4), with an intensity degree for each of soil texture,
CaCO3 and gypsum, as soil limitations, lies in the range of slightmoderate (rating = 90-75). In addition, the used irrigation water source
(underground water) lies in the first category of C1S1, where ECiw and
SAR values lay within the range of < 0.75 dS/m and < 6.00, respectively.
Moreover, the obtained data show that the abovementioned
vegetative growth parameters recorded the highest increases at
fertigation system followed by NPK fertilization as soil application under
drip and furrow irrigation ones. Also, available N and K contents in soil
behaved the same abovementioned trend of irrigation and fertilization
systems, with superiority for fertigation NPK one in soil surface (0-15
cm), may be due to their lesser by leaching. As for available phosphorus,
it was prone to fix at the point of application (soil surface). The
aforementioned trend was positively reflected on NPK uptake by plants
and tomato yield, where fertigation NPK exhibited relatively higher N, P
and K uptake as compared to NPK fertilization under drip and furrow
irrigation systems. The relative increases in tomato fruit yields reached
36.68 and 16.80% for fertigation and drip over the furrow irrigation
system, respectively. Fertigation NPK exhibited significantly higher fruit
number per plant (as an average of 56.9) followed by drip (50.4) and
furrow (43.7) irrigation systems.
The NPK fertilizers-use efficiency was reached a maximum
value at fertigation NPK (205.9 kg fruit kg-1 NPK), followed by NPK
fertilization as soil application under drip (175.9 kg fruit kg-1 NPK) and
furrow (150.6 kg fruit kg-1 NPK) irrigation systems. Thus, it could be
concluded that applying fertigation NPK system resulted in a pronounced
improvement of vegetative growth parameters, and in turn increasing
tomato yield and its fruit quality.