|Huang, Chi hua|
|Halvorson, Ardell - Collaborator|
Submitted to: Soil Science Society of America Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/4/2004
Publication Date: 7/31/2004
Citation: Zheng, F., Merrill, S.D., Huang, C., Tanaka, D.L., Darboux, F., Liebig, M.A., Halvorson, A.D. 2004. Runoff, erosion, and soil eordibility on crp lands converted to crop and hay production. Soil Science Society of America Journal.v. 68(4): 1332-1341. Interpretive Summary: Up to 39 million acres of US agricultural lands are authorized to be put into the CRP program, which is predominantly aimed at fragile and erodible cropland. There is concern that good soil conservation be practiced on those CRP lands that are returned to crop production. We conducted a rainfall simulation study on land in central North Dakota that had been used for a crop and hay production experiment that had been put on CRP land. The cropping portion of the experiment had been in a spring wheat - winter wheat - dry pea rotation under conventional-till (CT) and no-till (NT) management for 6 years. A permanent hayed (PH) treatment consisted of annual haying. We determined the vulnerability of various management alternatives to water erosion by measuring water runoff and sediment loss under artificial rainstorms that had rainfall rates from 1 inch per hour up to 5 inches per hour. We determined the erodibility of the treatments, which is the amount of soil loss generated by a given amount of rainfall and runoff energy. What we found was that the soil erodibilities of both NT and PH were low and the same as each other within experimental error. The annual preplant disk tillage of CT caused its erodibility to be 6-times higher than NT. These results show the soil conservation power of no-tillage, but it must be noted that our experiment was done on land with moderate 4% slope, with soil of higher quality, our rotation had high residue-producing crops 2 years out of 3, and we had higher than average rainfall in the preceding years. It is doubtful that no-till could perform as well under some combination of poorer quality soil, drought, and a lower residue-producing crop rotation.
Technical Abstract: There is concern that soil conservation and quality be preserved on CRP lands that are returned to crop production. Purified water was used for rainfall simulation study conducted after crop harvest in central North Dakota on Typic Argiustoll soil that had been converted to crop production 6 years prior with a spring wheat - winter wheat - dry pea rotation. Runoff and soil loss were measured on 1.5 x 5-m plots on 4% slope using initial long rainfalls (50 or 75 mm h-1, 1 to 3 h) followed by 10 to 20 min rains of 25, 50, and 75, or 75, 100, and 125 mm h-1. Land use treatments included conventional-till (pre-plant disk tillage: CT), no-till (NT), permanent hayed (PH), and multiple tillages of CRP (PC-TC). Surface conditions were undisturbed control, removal of plant residues, and disk tillage. Soil erodibility was calculated from ratios and regressions of soil loss rates versus runoff rates measured at relative steady state. Runoff at 50 and 75 mm h-1 rain for CT, NT, and PH averaged 9, 12 and 21 mm h-1, and soil loss was 20, 7, and 8 g m-2 h-1. Soil erodibilities of undisturbed CT, NT, and PH were 1.65, 0.29, and 0.28 g m-2 mm-1, showing NT did not differ from PH and that CT management increased erodibility 6-fold above PH. Tillage increased erodibility 3x for CT, 15x for NT, and 9x for PH (to 5.4, 4.2, and 2.6 g m-2 mm-1, respectively). Residue removal increased erodibility much less than tillage, from 1.2x for CT to 2.5x for NT. Our results indicate that NT management with chemical weed control can exhibit the same low soil erodibility as reestablished grassland under the conditions of study - higher quality soil, above average precipitation, and residue-productive crops. It is probable that combinations of lower quality soil, drought, and lower-residue crops would increase NT erodibility above grassland.