Subsoil nitrate and bromide uptake by contrasting alfalfa entries

The data clearly indicate nutrient stratification occurring within the row and with soil depth on three soils after 6 years of no-till cotton. Stratif ication of P was observed in the three soils. Mehlich-1 P was greater in th e IR position for two soils, but was greater in the BR position in one soil . Regardless of these results, soil test ratings would not have been affect ed by sampling position. Although differences in Mehlich-1 P were not of an y practical significance, additional time in no-till would be likely to mag nify these differences and so might affect fertilizer recommendations. Mehl ich-1 K was greater in IR samples and would have affected soil test ratings , depending on the soil and the fertilizer K rate. These data indicate that additional information on sampling techniques is needed to properly assess the nutrient levels of cotton fields after 6 years in no-till production. These data also indicate that additional information is needed to evaluate vertical stratification within different soils.