| dc.description.abstract | Manure is an important source of plant nutrients, primarily nitrogen (N) and phosphorus (P), as well as organic matter for improving soil health. However, agricultural activities, such as land application of manure, are reported to affect water quality either through runoff or leaching of nutrients, leading to eutrophication under conventional and no-till conditions. Therefore, choosing an optimum manure application rate for environmental management is important. The objectives of this study were (i) to quantify the impact of two manure types applied to a conventionally tilled (CT) soil and (ii) no-till (NT) soil under successive rainfall events on runoff, leaching, soil, and associated nutrient losses. In case of conventional tillage, surface Decatur silty clay loam (0-0.06 m) was collected and packed in trays (0.55 × 0.30 × 0.06 m3). Manure was surface-applied to the soil at rates ranging from 62 to 249 kg ha-1 for BL and 5 to 18 kg ha-1 for SLM, respectively. Rainfall events took place 7, 14, and 21 d after manure application. Results indicated that the runoff volume decreased at the highest manure application rate compared to the lowest manure application rate. The soil loss was lower in control compared to BL and SLM treatments. The loss of nitrate-N (NO3-N), dissolved reactive P (DRP), and dissolved organic P (DOP) in runoff water was maximum at the highest application rates for both the BL and SLM with respect to control. Mehlich 3 extractable-P (M3-P) and water-soluble P (WSP) increased with increasing P application rates for both manure types in soils following the rainfall simulation study. An increase in M3P and WSP, along with a decrease in soil P storage capacity following post-rainfall simulation for higher P application rates, indicates caution should be taken for considering the manure application rate to prevent environmental nutrient loss during runoff events.
For no-tillage, surface Holston fine sandy loam (0-0.06 m) was collected and packed in trays (0.55 × 0.30 × 0.06 m3). Broiler litter (BL) and SLM applications ranged from 42 to 168 kg P ha-1 and 4 to 15 kg P ha-1, respectively. Rainfall events took place at 7, 14, 21, 53, 60, and 67 days past the manure application. The application of BL at 168 kg P ha-1 was effective in controlling the runoff volume and soil loss in runoff water in contrast to control. The increase in the NH4-N in runoff was associated with the BL application rates, while NH4-N loss in leachate was linked to preferential flow. The DRP and DOP loss in runoff and leachate were linked with the application rates. The SLM application did not influence the runoff volume, however, the SLM application at 15 kg P ha-1 reduced the leachate volume. An increase in soil loss in the runoff with the SLM application rate at 4 kg P ha-1 (lowest) was observed compared to other SLM treatments. For SLM, an increase in TPP in runoff was observed with the increase in soil loss and rainfall events. In leachate, the DRP load was significantly greater with SLM application rate at 11 kg P ha-1 compared to the control. The dissolved organic P (DOP) load was significantly higher with SLM application at 7 kg P ha-1 in contrast to the control. The M3-P and WSP in the post-experimental soil increased with increasing P application rates, irrespective of manure type. The negative soil phosphorus storage capacity (SPSC) values for both the manure types highlight the soil acting as the source for P, and in addition, P application will be susceptible to P loss. | en_US |
