쌀 분말이 함유된 생분해성 멀칭필름이 고구마 생육에 미치는 영향

Efects of Biodegradable Mulching Films Containing Rice Powder on Sweetpotato Growth

쌀 분말이 함유된 플라스틱 수지를 이용하여 생분해성필름 시제품 2종을 생산하고, 고구마(Ipomoea batatas L. Lam) 재배에 적용하여 생육과 수량, 토양환경 등을 PE (Polyethylene) 필름과 비교한 결과는 다음과 같다. 1. 투광율은 350 mesh 쌀 분말 30% 함유된 생분해성 필름(BF30-350RP)이 0.8%로 500 mesh 쌀 분말 40% 함유된 생분해성 필름(BF40-500RP) 2.0%, PE 필름 2.7%보다 낮았다. 2. 맑은 날 필름의 표면온도는 PE 필름이 가장 낮았고, BF40-500RP와 BF30-350RP는 차이가 적었다. 3. 농작업 충격에 의한 손상율은 PE 필름 0.4%, BF500- 400RP 3.3%, BF350-30RP 5.3% 순으로 낮았다. 4. 외부에 노출하였을 때 BF40-500RP와 BF30-350RP의가시적인 분해 시점은 각각 노출 40일과 30일 차이었고, 노출 90일 차에 각각 62.3%와 70.4% 분해되었다. 5. 고구마 재배에 적용된 생분해성 필름의 분해는 BF40-500RP 가 BF30-350RP보다 서서히 진행되었다. 두둑 표면부의BF40-500RP는 고구마 삽식 30일 후에 5%, 60일 후에30%, 90일 후에 55%, 120일 후에 90% 분해되었다. 두둑과 고랑 경계부의 생분해성 필름은 고구마 삽식 75일후에 완전히 분해되었다. 6. 멀칭 후 고구마를 재배하지 않아 지표면이 밀폐된 조건에서는 토양습도와 그 편차는 PE 필름, BF40-500RP, BF30-350RP 순으로 낮았으나 큰 차이를 보이지 않았고, 토양온도는 PE 필름이 생분해성 필름보다 높았으나그 차이는 낮았다. 7. 고구마 삽식 2개월 후에 7일 동안 일평균 토양습도는BF30-350RP 멀칭 2.5%point, BF40-500RP 멀칭 1.5%point, PE 필름 멀칭 1.1%point 씩 감소하였고, 토양온도는 두생분해성 필름 멀칭 모두 비슷하였으나 PE 필름 멀칭은지속적으로 증가되어 생분해성 필름보다 일평균 0.1°C 높았다. 8. 고구마 줄기 생육과 괴근 수량은 멀칭 필름간 차이가 관찰되지 않았다.

In this study, two types of biodegradable film prototypes were produced using plastic resin containing rice powder. The application of these biodegradable films in sweetpotato (Ipomoea batatas L. Lam) fields and their impacts of plant growth, yield, and the soil environment were assessed, in comparison with Polyethylene (PE) film. The light transmittance of the biodegradable film containing 30% of 350 mesh rice powder (BF30-350RP) was 0.8%, which was lower than the 2.0% light transmittance of the biodegradable film containing 40% of 500 mesh rice powder (BF40-500RP) and 2.7% light transmittance of PE film. Surface temperature measurements on clear day indicated that the PE film exhibited the lowest temperature, with the minimal difference observed between BF40-500RP and BF30-350RP. Assessment of the damage ratio resulting from agricultural work revealed a ranking of 0.4% for the PE film, 3.3% for BF500-400RP, and 5.3% for BF350-30RP. Visible decomposition of BF40-500RP and BF30-350RP commenced after 40 and 30 days of outdoor exposure, reaching 62.3% and 70.4% decomposition at 90 days post-exposure, respectively. The decomposition of biodegradable films applied to sweetpotato fields progressed more slowly in BF40-500RP than in BF30-350RP. The BF40-500RP film on the surface of the ridges was decomposed by 5%, 30%, 55%, and 90% after 30, 60, 90, and 120 days after planting sweetpotato cuttings, respectively. Both types of biodegradable films at the ridge and furrow borders were completely decomposed after 75 days of sweetpotato planting. In a field where the surface was sealed by mulching without growing sweetpotatoes, the soil moisture and its deviation were lower in the order of PE film, BF40-500RP, and BF30-350RP, but the differences were not significant. The soil temperature was higher for PE film mulching than for the biodegradable films containing rice powder, but the differences were small. Two months after sweetpotato planting, the daily average soil moisture decreased by 2.5%point for BF30-350RP mulching, 1.5%point for BF40-500RP mulching, and 1.1%point for PE film mulching over seven days. Soil temperature was similar for both biodegradable film mulches, but increased steadily for the PE film mulch, reaching a daily average of 0.1°C higher than for the biodegradable films. Sweetpotato vine growth and tuber yield were similar for all the mulching films tested.