Organic amendments have been used to restore productivity to disturbed soils such as those
on abandoned oil and natural gas wellsites. A study was conducted on three abandoned well-
sites in southern Alberta, Canada to examine the effects of one-time applications of alfalfa
(Medicago sativa L.) hay or beef cattle (Bos taurus) feedlot manure compost on soil properties
under continuous wheat (Triticum aestivum L.). The base amendment rate (1×) [dry wt.]
was 5.3 Mg ha−1 for compost and 3.1 Mg ha−1 for alfalfa. The fi ve amendment rates of 0,
1×, 2×, 4×, and 8× were soil-incorporated at the wellsites. Although approximately twice as
much C was applied with alfalfa than with compost, fi nal SOC content was similar for the
two amendment treatments, indicating the greater stability of compost-derived C. Nitrate N
content in the 0- to 60-cm depth was not affected by compost rate (mean 213 kg ha−1) but
increased by 7.78 kg ha−1 for each Mg ha−1 increase in alfalfa rate. This result refl ects the
greater stability of compost-N compared with alfalfa-N and suggests a lower risk of NO3–N
leaching with compost application. Compost rates >20 Mg ha−1 resulted in excessive extract-
able P build-up in the topsoil (up to 95.7 mg kg−1), which may pose environmental risk
to surface water. We recommend amending wellsites with up to 12 Mg ha−1 of alfalfa or
<20 Mg ha−1 of compost during reclamation to improve C storage and nutrient cycling
while minimizing nutrient loss to water systems.