Abstract:
In order to study possibility of using wastes as nitrogen (N) source for guava (Psidium guajava L.) cv. Yen Song, activated sludge cake (AS) from alcohol distillery factory and filter cake (FC) from sugar refinery factory were used in the field experiment conducted in Kamphaeng Saen soil series. The experiment was performed in Randomized Complete Block Design with 4 replications using 6 treatments: no N (Ch), chemical fertilizer (IF), AS, FC, and mixing of the half dose of the wastes and the IF which were ? AS + ? IF and ? FC + ? IF. The application rate of N to the plant was 60 g N/plant/time. The application of this rate was done every two months. The experiment was conducted continuously for one year. The application of the treatments, therefore, was performed at the mentioned rate 5 times.The results showed that the waste treatments, either the sole application or the combination with IF, was significantly superior than Ch in terms of number of marketable fruits number of unmarketable fruits, fruit size (fruit width and fruit length), flesh thickness, total soluble solid (TTS), titratable acidity (TA), and TSS/TA. Combination of the activated sludge cake with the chemical fertilizer (1/2 AS + ? IF) was the efficient N source for guava more or less the same as IF. In addition, continued application of the organic wastes, either AS or FC, for one year tended to improve soil physical properties and plant nutrients in the soil.