Nutrient Leaching Losses from Continuous Application of Washed Rice Water on Three Contrasting Soil Textures

Abstract

Washed rice water (WRW) is often used as liquid plant fertilizer. However, there is no study on nutrient leaching of soils due to frequent WRW application. Therefore, a column study was undertaken to evaluate the rate of nutrient leaching losses, nutrient retention, and recovery of elements in leachates of three different soil textures irrigated with WRW. The treatments were 3 soil textures and 2 water types. The treatments were evaluated for 8 weeks, and the soils and leachates were measured biweekly. Factorial and repeated measurements in a completely randomized design were therefore employed. Higher cumulative leaching of the elements was found in sandy clay loam soil with 666.29, 378.13, 138.51, 50.82, 44.61, and 27.30 mg L-1 of K, P, Mg, Ca, NH4+-N, and NO3--N, respectively. Higher percentages of elements recovery in leachate were found in the sandy clay loam soil with a range of increase by 37.8–283.1% than the other two soil textures. In contrast, after 8 weeks of WRW application, the clay and silt loam soils had a range of increase in nutrient retention by 0.43–1358.5% than the sandy clay loam, with P and NO3--N being the highest and the lowest elements retained, respectively, for all soil textures. This study showed that frequent WRW disposal on sandy textured soils risks higher environmental contamination, mainly due to the soil’s lower water retention and nutrients, leading to nutrient leaching. Therefore, organic amendments should be added to sandy textured soils.

Combined benefits of fermented washed rice water and NPK mineral fertilizer on plant growth and soil fertility over three field planting cycles

“…Notably, this study tested the combined effects of NPK and R3 (N0.5R3), and their combination resulted in the most favorable outcomes for plant growth and nutrient uptake. However, despite the benefits of WRW, this study also highlighted potential challenges such as the lack of observed carryover effects, likely owing to the vulnerability of liquid WRW to leaching, especially in coarse-textured soils, as observed by [ 56 ]. The findings of this study underscore the importance of considering environmental factors and soil texture when applying liquid fertilizers such as WRW, and suggest that preventive measures, such as surface mulches, would be beneficial for mitigating nutrient leaching losses.…”

“…Moreover, the soil texture at this study site was sandy clay with 52% sand and 35% clay ( Table 1 ). [ 56 ] found that the extent of leaching loss from WRW depended on soil texture. Applying 5 mm of WRW daily to a sandy clay loam soil (72% sand; 22% clay) over eight weeks resulted in 13–20% more leaching volume and 21–47% higher nutrient losses, particularly K (due to its high mobility in soils), than silt loam (28% sand; 18% clay) and clay (26% sand; 65% clay) soils.…”

“…This omission complicates the process of comparing our findings with those of previous WRW studies, especially regarding soil bacterial populations, a parameter seemingly overlooked in other studies. Only the most recent investigations [ [19] , [20] , [21] , 36 , 37 , 56 ] have sought to rectify these deficiencies by undertaking a more methodical approach to WRW research. Yet, the results from these studies were derived from laboratory and rainshelter settings.…”