The Effect Of Regulation To Drip Condition On Radish Nutrient Uptake

The effects of controlled soil matric potential and irrigation frequency on uptake of radish in northern China plain were studied in this paper. Soil matric potential treatments were controlled by 20cm depth soil matric The treatments consist of five controlled soil matric potential, namely, W1 (-15kPa), W2 (-25kPa), W3 (-35kPa), W4 (-45 kPa), W5 (-55kPa) respectively. Irrigation frequency treatments consist of once 1 day(F1),once 2 days(F2),once 3 days(F3),once 4 days(F4),once 6 days(F6)and once 8 days(F8), take evaporation of W2 the day before as the irrigation amount of F1,and take evaporation of W2 the two days before as the irrigation amount of F2, and sequential analogy on the irrigation amount of F3, F4, F6, F8. Experiment applied randomized blocks design; all treatments were replicated three times. Main experiment results were shown as followed::In Different soil matric potential treatments the matric potential at 20cm depth under emitter fluctuated at their required, the higher matric potential treatment has the bigger range of change, and the matric potential at 10cm depth and 30 cm depth has the same change trend as 20cm. The deeper of soil profile the less change of soil matric potential for all the treatments. Soil matric potential at 10~30 cm has little change range for high frequency treatment, and soil matric potential at the deep profile is little affected by drip frequency, but by the growth of radish.W3 has a highest accumulation of biomass, at harvest the stems and leaves accumulation of W3 is 1.17~1.53 times than that of the other treatments. And the roots dry weight accumulation is 14~17% higher than that of the others. To the frequency treatments, the higher drip frequency, the more biomass accumulation, at harvest time F1 is the highest, which is 32.1% higher than F8 for root dry weight.The content of N, P, and K in radish has a decrease trend during all the life. However, the accumulation still increased. The nutrient uptake of W3 were higher than that of other treatments in soil matric potential treatments, its N, P, K accumulations of W3 were higher 22~41%, 20~42%, 15~41% than other treatments respectively. In the frequency treatments, N uptake of F1 is highest in frequency treatments, which was higher 17~62% than other treatments. P uptake of F1 was close to that of F2, which is higher than that of F3 and F4. F 6 and F8 has similar P uptake which was lower than that of F3 and F4. K uptake of F1 was highest, which was higher 7~62% than other treatments.After radish harvest, valid nitrogen and kalium in soil were affected by uptake of radish, the more uptakes, and the less content of valid nutrient, however valid P content in soil decreased when the soil matric potential increased. And valid nutrient content in soil fell down with rising frequency.The method of controlled water for drip is optimal for –35kPa matric potential at 20cm depth under emitters if there is water at any time. If there not good condition for water and use 1 day once as drip frequency, at least the drip frequency is higher than 6 day once.