Irrigation well water in Nebraska: essential nutrient contents and other properties

Water nutrient concentrations and other properties were surveyed by sampling water from 642 irrigation wells in Nebraska. The amount of Ca, Mg, S, Cl, and B applied in irrigation exceeds removal in 15 Mg ha-1 of corn (Zea mays L.) grain harvest for most wells. Irrigation supply exceeded corn grain harvest removal of K, Mn and Mo for >20% of the wells. The supply of P, Zn, Cu, Fe, and Mo was generally very low but sufficient with some wells to be considered in nutrient management plans. The median level of nitrate N was 4.4 ppm with 25% of the wells having >10 ppm NO3-N which is above the suitability limit for human consumption. The agricultural lime equivalent applied with one or two ML of irrigation was enough to neutralize the acidifying effect of 200 kg ha-1 of fertilizer-N for 70% or 89% of the wells. Nutrient and lime supply was relatively low for Sandhills wells and relatively high for wells in river valleys of <100 ft depth. No wells had excessive Na levels but 0.3% of t...研究人员对内布拉斯加州（Nebraska）的642口灌溉井采集水样，对水体的养分浓度及其他理化性质开展了系统调查。针对多数灌溉井，灌溉施加的钙（Ca）、镁（Mg）、硫（S）、氯（Cl）与硼（B）的总量，超出了单公顷收获15 Mg·ha⁻¹玉米（Zea mays L.）籽粒所携出的对应养分量。超过20%的灌溉井中，灌溉供给的钾（K）、锰（Mn）与钼（Mo）总量，超出了玉米籽粒收获时的携出量。磷（P）、锌（Zn）、铜（Cu）、铁（Fe）及钼（Mo）的供给整体偏低，但部分灌溉井的养分供给量已达到养分管理规划的考量标准。硝酸盐氮（NO3-N）的中位数浓度为4.4 ppm，其中25%的灌溉井中硝酸盐氮浓度超过10 ppm，该数值超出了人类饮用水的适宜限值。对于70%或89%的灌溉井，单次或两次灌溉所施加的农用石灰当量，足以中和每公顷施用200 kg·ha⁻¹氮肥所产生的酸化效应。沙丘带（Sandhills）区域的灌溉井养分与石灰供给量相对偏低，而深度不足100英尺的河谷区域灌溉井的供给量则相对较高。未发现钠（Na）浓度超标的灌溉井，但有0.3%的