following the winter wheat harvest. "In order of performance, the legumes were ranked for aboveground yield with AWP averaging 1060 kg/ha or 945 lbs/ac and berseem clover averaging 766 kg/ha or 683 lbs/ac," he says. This year, Balansa clover was not harvested due to low growth. Schneider adds that because they had seen some promising results in plot trials with berseem clover planted in early June, they wanted to see how it would do planted postwinter wheat (planted around early August). "We wanted to include the legumes as both monocultures and mixtures in order to be able to confidently say which species is providing the nitrogen credit," she says. "However, if a farmer were to harvest a cover crop for forage, they would be more likely to plant the legume in a mixture with a cool season annual grass like oats, for example. This will increase the yield and make it more suitable as a feed. But we wanted to see if there would still be enough legume in order to provide a nitrogen credit. Preliminarily, the grasses do compete with the legumes, so sometimes there was not much legume left when planted in a mixture. The AWP likely did the best in the mixtures." And how might the uniformity of red clover stands be improved? One way is to alter winter wheat row spacing. Lee explains, "I think that the general consensus is that red clover stands become highly variable when wheat yields are high, meaning wheat is outcompeting the red clover for light and/or moisture. There had been some farmer research on Twitter about dropping every third row in a conventional wheat stand that my master's student Brett Hilker came across, and this intrigued him. He suggested that we include that as an additional treatment in his trials. And wow, what a difference it made." Lee says of their conclusions on that front so far, "first take-home message: twin row wheat under high-yield conditions results in considerably high red clover stands, but there is a variety effect. Second take-home message: if you want good red clover stands, it starts with picking the right wheat variety. We do not know exactly what is going on here, but it is not competition for light. Our current 12 working hypothesis is that some wheat varieties have better water use efficiencies and therefore are not as hard on the underseeded red clover. Last take-home message: “The higher the red clover stand, the higher the subsequent corn grain yield is.” IMPROVING 4R In this project, the well-known and highlyimplemented 4R commercial fertilizer nutrient stewardship practices are being refined for Ontario crop farmers in corn and soybean production systems currently or previously receiving manures. Dr. Tiequan Zhang, a research scientist at the Agriculture & Agri-Food Canada Harrow Research and Development Centre, is working on this topic with Christine Brown, OMAFRA field crop sustainability specialist, in collaboration with Greg Patterson, CEO at A&L Laboratory Canada in London, Ont. They note that current 4R practices in Ontario have been developed under conditions where only chemical fertilizers were applied — and manure-amended cropping systems have different management requirements than those receiving only commercial fertilizer. Current Ontario 4R recommendations also do not consider the impacts of soil texture on manure nitrogen availability. Zhang and Brown explain that soil textures impact the breakdown (mineralization) of organic nitrogen and nitrogen losses which collectively alters crop nitrogen availability. Given the same quantity and quality of organic substances, sandy soils can have higher nitrogen release from organic matter breakdown as well as nitrogen leaching, while heavier soil textures can lose more nitrogen through denitrification when soils are saturated and warm for an extended period (and they can also lose N2O during spring thaw and when soils are saturated and cold). Zhang further explains that they are investigating both pig and cattle manure in this study, as well as various forms (liquid versus solid and composted liquid pig manure). "Another key factor, which is unique and innovative in this study compared with those in the literature, is that the long-term residual (or legacy) effect of manure addition is also taken into consideration for determination of fertilizer value of manure phosphorus," he says. "The portion of phosphorus in manure that is not used by crops in the year of application may still be available to and used by crops the following year(s)." In this study, the team is quantifying this portion of phosphorus applied in manure and adding it to the fertilizer values of manure phosphorus. This can then be used to guide farmers' 4R application practices. In terms of manure use, Brown says it is increasing in Ontario with better management options available and also due to the jump in fertilizer prices. She says that while transportation costs are higher, the increased fertility value combined with organic matter and soil health benefits are resulting in manure being economical at greater distances — especially solid poultry manure and liquid manure (such as finisher hog) with concentrated nutrients (that is, not materials that are 99 per cent water content). "It would be great to put a value on the organic matter contribution of manure," she says, "but that value is different for livestock farms that have diverse rotations and regular manure versus crop farms that use only commercial fertilizer." Zhang adds that composting can be an excellent approach to reduce manure volume with concentrated nutrients and reduce transportation costs. Once the practices recommended by this project are being used, the impact will not be immediate. However, Zhang and Brown believe that the 'perfect storm' has arrived for increased manure use due to higher fertilizer prices, awareness of manure impact of improving soil health, the increased focus on reducing GHG emissions and phosphorus run-off, and new manure application technologies being introduced. This project received additional funding from the Ontario Pork Producer’s Marketing Board. These research projects were funded [in part] by the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), through the Ontario Agri-Food Innovation Alliance. l continued from page 11
RkJQdWJsaXNoZXIy MTQzODE4