Schuller P, Walling D E, Sepúlveda A, Trumper R E, Rouanet J L, Pino I, Castillo A
Universidad Austral de Chile, Valdivia, Chile.
Appl Radiat Isot. 2004 May;60(5):759-66. doi: 10.1016/j.apradiso.2003.11.087.
Intensification of agricultural production in south-central Chile since the 1970s has caused problems of increased soil erosion and associated soil degradation. These problems have prompted a shift from conventional tillage to no-till management practices. Faced with the need to establish the impact of this shift in soil management on rates of soil loss, the use of caesium-137 (137Cs) measurements has been explored. A novel procedure for using measurements of the 137Cs depth distribution to estimate rates of soil loss at a sampling point under the original conventional tillage and after the shift to no-till management has been developed. This procedure has been successfully applied to a study site at Buenos Aires farm near Carahue in the 9th region of Chile. The results obtained indicate that the shift from conventional tillage to no-till management has caused net rates of soil loss to decrease to about 40% of those existing under conventional tillage. This assessment of the impact of introducing no-till management at the study site must, however, be seen as provisional, since only a limited number of sampling points were used. A simplified procedure aimed at documenting the reduction in erosion rates at additional sampling points, based solely on measurements of the 137Cs inventory of bulk cores and the 137Cs activity in the upper part of the soil has been developed and successfully tested at the study site. Previous application of 137Cs measurements to estimate erosion rates has been limited to estimation of medium-term erosion rates during the period extending from the beginning of fallout receipt to the time of sampling. The procedures described in this paper, which permits estimation of the change in erosion rates associated with a shift in land management practices, must be seen as representing a novel application of 137Cs measurements in soil erosion investigations.
自20世纪70年代以来，智利中南部农业生产的集约化导致了土壤侵蚀加剧及相关土壤退化问题。这些问题促使人们从传统耕作方式转向免耕管理实践。面对确定这种土壤管理转变对土壤流失率影响的需求，人们探索了使用铯-137（¹³⁷Cs）测量方法。现已开发出一种新颖的程序，利用¹³⁷Cs深度分布测量来估算在原始传统耕作下以及转变为免耕管理后采样点的土壤流失率。该程序已成功应用于智利第9大区卡拉韦附近布宜诺斯艾利斯农场的一个研究地点。获得的结果表明，从传统耕作向免耕管理的转变已使土壤流失净速率降至传统耕作下现有速率的约40%。然而，对该研究地点引入免耕管理影响的这一评估必须视为临时的，因为仅使用了有限数量的采样点。已开发出一种简化程序，仅基于对整块土芯¹³⁷Cs存量和土壤上部¹³⁷Cs活度的测量，旨在记录其他采样点侵蚀率的降低情况，并已在该研究地点成功测试。先前应用¹³⁷Cs测量来估算侵蚀率仅限于估算从沉降开始到采样时这一期间的中期侵蚀率。本文所述的程序允许估算与土地管理实践转变相关的侵蚀率变化，必须视为¹³⁷Cs测量在土壤侵蚀调查中的一种新应用。
