Effect of Liquid Pig Manure on Growth, Nutrient Uptake of Onion, and Chemical Properties in Soil

Abstract

This study was carried out to evaluate the effect of liquid pig manure (LPM) on the nutrient uptake, yield of onion and soil properties. The LPM applied to onion field contained 4.2 g kg?¹ N, 0.34 g kg?¹ P, 1.2 g kg?¹ K and it was diluted with water by 1:2 for top-dressing, which was applied separately 4 or 6 times from February to April. The LPM application rate for basal fertilization was 19,280 kg ha?¹ which included 80 kg N, 6.6 kg P, and 22 kg K. The application rate for top-dressing was 101,910 kg ha?¹ which included 160 kg N, 13 kg P, and 53 kg K. The plant height was not almost different among treatments until 136 days after planting. Thereafter, it enlarged abruptly until 186 days, on May 4. The significant difference among CF and LPM ＋ top-dressing by CF or LPM I was not shown, but no fertilizer and LPM only (it was applied totally as basal fertilization) made plant height of onion lessen at the maximum growth stage because of insufficient nutrients. The plant diameter increased after 136 days, and there was a significant difference between CF or LPM and no fertilizer from 186 days after planting. The leaf weight was similar tendency to plant height while bulb weight was similar to plant diameter. The amount of nutrient uptake in leaf coincided with leaf growth and the nutrient uptake in bulb swelled simultaneously with bulb growth. The difference between CF and LPM ＋ top-dressing by CF or LPM I was not significant in nutrient uptake of onion leaf and bulb. But LPM only decreased in nitrogen and potassium of leaf and in nitrogen of bulb. And no fertilizer made a remarkable difference to others in nitrogen, potassium and magnesium of leaf and bulb. The utilization of nitrogen and phosphorus in LPM ＋ top-dressing by CF were 23.5％, 13.2％ respectively, more than the others. The LPM ＋ top-dressing by LPM I was most available with potassium, and it leaded the most abundant marketable yield by 55.0 t ha?¹ as well. The nitrogen, phosphorus, and potassium contents in bulb were inclined to decrease with progress of onion growth. The nitrogen contents in leaf maximized at the initial growth stage while potassium contents increased at the initial bulbing stage. The LPM application increased pH, nitrate nitrogen, potassium and EC in soil more than chemical fertilizer (CF) did.