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Abstract

This study aimed to investigate the effect of using high quality organic fertilizers and

different rates of chemical fertilizer on chemical properties of soil, growth and yield, as well as
economic return, of Chinese kale. The experiment was conducted under field conditions at

Ban Sambath, Nong Prao Ngai sub-district, Sai Noi district, Nonthaburi province during June 2014

to March 2016. The field experimental design was Randomized Complete Block Design (RCBD)
with 5 treatments and 4 replicates. The treatments consisted of 1) no application of fertilizer,

2) chemical fertilizer (15-15-15) at the rate of 34 kg/rai, 3) high quality of N organic fertilizer at a
rate of 100 kg/rai, 4) chemical fertilizer (urea; 46-0-0) at the rate of 44 kg/rai (laboratory test) and

5) chemical fertilizer (25-7-7) at the rate of 160 kg/rai (conventional practice).

For the first year, the results showed that pH values of soil treated with urea fertilizer
was significantly reduced, while other treatments showed a slight increase in soil pH.

Comparing between prior and after study, organic matter in treatment received high-quality
organic fertilizer was significantly increased from 2.28% to 2.47%, while it was largely reduced

in the rest of treatments. Available P and K were slightly reduced. Yield of Chinese kale

received conventional management of fertilizer rate of 160 kg/rai was 2,633 kg/rai, with the
economic return of 33,244 baht/rai, followed by plant received urea fertilizer rate of 44 kg/rai,

produced 2,380 kg/rai, with the economic return of 31,039 baht/rai. While the yield of plant
received high quality of N organic fertilizer was lowest, with account for 1,273 kg/rai, with the

economic return of 10,804 baht/rai.

For the second year, soil pH, organic matter and available P were significant reduced in
all treatments, while available K in soil was significantly increased, comparing between prior

and after study. Yield of Chinese kale showed similar trend to the previous year. Plants
received conventional management of fertilizer yielded 2,410 kg/rai, with the economic return

of 29,230 baht/rai while yield of plants received urea treatment was 2,157 kg/rai, with the

economic return of 27,025 baht/rai, and plants received high quality of N organic fertilizer
yielded 2,004 kg/rai, with the economic return of 23,962 baht/rai.

From the results, although the use of conventional management of fertilizer produced
greater yield and economic return, compared to the rest of treatments, Benefit and

Cost Ratio (B/C ratio) was lower than the use of urea. This indicates that the use of urea

provided better cost effectiveness than the rest of treatments.