Yield and water balance response of Italian ryegrass to different fertilizer application amount in weighable lysimeter

다국어 초록 (Multilingual Abstract)

This study investigated the growth characteristics and water balance of Italian ryegrass under different soil texture and fertilizer application amount using a weighing lysimeter. Fertilizer treatments were set at one and two times of the standard application amount. Study used three soil textures including silty clay loam (SiCL), loam (L), sandy loam (SL). Water balance analysis was conducted by estimating rainfall, irrigation, and evapotranspiration from lysimeter weight changes, while drainage was measured with a tipping counter, and runoff was collected directly.
The growth survey showed statistically significant differences depending on soil texture, with L providing the most favorable growth. In contrast, fertilizer application amount had no significant effect, suggesting that excessive fertilization may reduce yield in Italian ryegrass, despite its high nutrient demand. Water balance analysis showed similar water inflow among treatments, while water outflow was highest in L due to greater evapotranspiration. As evapotranspiration is positively correlated with yield, the higher yield in L likely led to increased evapotranspiration.
Drainage was greatest in SiCL, possibly due to winter cracking associated with its high clay content. Fertilizer application showed no significant effect, likely because higher fertilizer levels increased transpiration through greater plant growth but reduced soil evaporation via larger leaf area, resulting in little difference in total evapotranspiration. Overall, water balance was negative values. These results indicate that water balance analysis by fertilizer input amount and growth stage, combined with meteorological factors, provides baseline information for water management optimization in Italian ryegrass under different fertilizer application amount.