Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2007
Publication Date: 6/26/2007
Citation: Garcia, J.P., Wortmann, C.S., Mamo, M., Drijber, R., Quincke, J.A., Tarkalson, D.D. 2007. Nutrient stratification, mycorrhizal colonization of roots, and plant phosphorus uptake as affected by one-time tillage of no-till systems. Agronomy Journal. 99:1093-1103. Interpretive Summary: Stratification of nutrient availability, especially of phosphorus, that develops with continuous no-till can affect runoff nutrient concentration and possibly nutrient uptake. Research in conducted in Eastern NE assessed the effects of composted manure application and one-time tillage of no-till on the distribution of soil chemical properties, corn and sorghum root colonization by arbuscular mycorrhizae, and plant P uptake. Tillage treatments included no-till, disk, chisel, moldboard plow, and mini-moldboard plow. Subplots had either 0 or 87.4 kg phosphorus ha-1 applied in compost before tillage. Moldboard plow and mini-moldboard plow effectively redistributed nutrients within the soil profile. Tillage reduced arbuscular mycorrhizae colonization. The results do not indicate any advantage to one-time tillage of no-till if runoff phosphorus loss is not a concern.
Technical Abstract: Stratification of nutrient availability, especially of P, that develops with continuous no-till (NT) can affect runoff nutrient concentration and possibly nutrient uptake. The effects of composted manure application and one-time tillage of NT on the distribution of soil chemical properties, root colonization by arbuscular mycorrhizae (AM), and plant P uptake were determined. Research was conducted on Typic Argiudoll and Mollic Hapludalf soils under rainfed corn (Zea mays L.) or sorghum [Sorghum bicolor (L.) Moench.] rotated with soybean [Glycine max (L.) Merr.] in eastern Nebraska. Tillage treatments included NT, disk, chisel, moldboard plow (MP), and mini-moldboard plow (MMP). Subplots had either 0 or 87.4 kg P ha21 applied in compost before tillage. Bray-1 was five to 21 times as high for the 0- to 5-cm as compared with the 10- to 20-cm soil depth. Greater redistribution of nutrients and incorporation of compost P resulted from MP tillage than from other tillage treatments. One-time chisel or disk tillage did not effectively redistribute nutrients while MMP tillage had an intermediate effect. Compost application reduced AM colonization of roots at R6 for all crops. Tillage reduced AM colonization with reductions at R6 due to MP tillage of 58 to 87%. The tillage effect on colonization persisted through the second year with no indication of AM recovery. Root P concentration was increased by MP and was negatively correlated to colonization. Decreased colonization did not result in decreased plant P uptake. Infrequent MP tillage can reduce surface soil P and the potential for P loss in runoff, but may reduce AM colonization of the roots, possibly reducing P uptake with some low P soils. The results do not indicate any advantage to one-time tillage of NT if runoff P loss is not a concern.