Refer to Manure Spreading Advisory #2 of 2015 for the current Advisory. The following Update does not change the Advisory.
When balancing the goal of maximizing corn yields with the goal of establishing cover crops, consider the effect of cover crop planting date (Table 1).
Table 1. Nitrogen uptake by cover crops decreases with later planting dates. Values are for B.C. South Coast. Actual uptake depends on crop variety and other factors.
|Approximate Planting Date||Nitrogen Uptake|
|Before August 15||Up to 140 kg N/ha|
|August 22||60 to 95 kg N/ha|
|September 5||30 to 50 kg N/ha (legumes); |
60 to 95 kg N/ha (non-legumes)
|September 15||Less than 45 kg N/ha|
Does nitrogen need to be applied in the fall to establish the cover crop? In many cases, the anser is 'no' or 'not much', due to typical levels of soil N after corn harvest. (Table 2).
Table 2. Average soil nitrate N (0-30 cm depth) after corn harvest (without fall manure application) in 2 field surveys in the Lower Fraser Valley. These nitrate amounts could be used by cover crops, if planted early enough.
|Year of Survey||Post-harvest nitrate N|
|2005 (typical summer)||75 kg N/ha (22 fields)|
|2012 (hot and dry late summer||76 kg N/ha (28 fields)|
Earlier cover crop establishment provides greater flexibility for responsible manure use.
Reference: Bittman, S., Hunt, D.E. and Kowalenko, C.G. 2004. Cover crops and relay crops. In: Bittman and Kowalenko (eds.), Advanced Silage Corn Management, Pacific Field Corn Association, Agassiz, B.C. pp 89-93.
Producers are responsible for decisions regarding manure spreading. Legislation gives no specific dates for manure spreading but it does not allow for manure to be spread in a manner that causes pollution. This Update is produced by government, in partnership with industry, to provide guidance to farmers regarding the Agricultural Waste Control Regulation and the ENVIRONMENTAL MANAGEMENT ACT. If a discrepancy arises between this document and the legislation, the legislation takes precedence. Following this advisory does not relieve anyone from their obligations under the LEGISLATION. The Province of British Columbia does not guarantee the accuracy or completeness of the information referenced here from legislation, and in no event is the Province liable or responsible for damages of any kind arising out of its use.