Derek E. Hunt

Nitrogen status of pollen donor affects kernel set and yield components in corn

ABSTRACT Nitrogen (N) status of corn plants influences yield performance through adjustment of yield components. Physiological function of corn pollen produced under N-stressed conditions has not drawn enough attention in genotype selection and breeding programs. The object of this study was to assess effects of N nutrition of the pollen donor on kernel set and yield components of the pollen recipient in a field trial by using a restricted pollination procedure. Pollen from plants receiving 0 and 240 kg N ha−1 was manually applied to plants receiving 0, 80, 160, and 240 kg N ha− 1 during silk emergence. The high rate of N fertilizer applied to the pollen donor significantly increased kernel number, kernel weight, harvest index, and aboveground biomass in the pollen recipient. The effect of N nutrition of the pollen donor was similar at all N levels that were applied to the pollen recipient so the interaction was not significant for any of the variables.

Emissions of nitrous oxide after application of dairy slurry on bare soil and perennial grass in a maritime climate

Over half the slurry manure produced on dairy farms in the high-rainfall, coastal region of British Columbia (BC), Washington State and northern Oregon is applied from mid-February to early May. This study was conducted to compare the emissions of nitrous oxide (N2O) after manure application during this period on perennial forage grass or winter fallow land. The experimental site soil was moderately well- to well-drained medium-textured river deposit of the Monroe series. Treatments consisted of liquid dairy manure applied either at 270 (Early) or 450 (Late) Tsum (accumulation of average air temperatures above 0oC from Jan. 01) on bare land or a perennial stand of tall fescue (Festuca arundinacea Schreb.) at a rate of 55.5 m3 ha-1 giving a total ammoniacal N (TAN) loading of 100 and 111 kg ha-1 in 2001 and 2002, respectively. An additional grass treatment consisted of split applications (Split) of manure at half the rate on each of the two application dates. Untreated (Control) bare and grass treatments w...

Effect of polymer-coated urea on nitrous oxide emission in zero-till and conventionally tilled silage corn

Abstract: Little is known about nitrous oxide (N2O) emission from silage corn (Zea mays L.). Studies have shown that controlled-release N fertilizers have the potential to reduce N2O emissions, compared with conventional N fertilizers. This 2-year field study compared N2O emissions from urea fertilizer and a slow-release polymer-coated urea (CRU) applied to silage corn on soils managed with conventional tillage (CT) and zero tillage (ZT). The study was conducted on a silty loam soil in the cool, moist climate of south coastal British Columbia, Canada, taking year-around measurements from static chambers. Over 2 study years there was a significant interaction between N sources and tillage methods; under CT there was no significant difference between CRU and urea (557 vs. 447 g N2O-N ha-1 year-1, respectively), but under ZT, emissions from CRU were significantly higher than from urea (968 vs. 381 g N2O-N ha-1 year-1, respectively). Annual emissions of N2O-N ranged from 0.09 to 0.65% of applied N fertilizer. The CRU also had significantly greater emissions than urea per unit N uptake and plant yield under ZT, while there was no significant difference between N sources under CT. The results do not indicate that NO3 - release from broadcast CRU matches corn growth or reduces emission of N2O.

Sustainable Cropping Systems

About 11% of the earths land surface, typically in the most favorable areas, is used to produce the food we eat. In light of increasing population and growing worry about the environment the challenge for humanity and for the agricultural enterprise in particular is to ensure sustainable cropping systems and to minimize harm to soil, water, and air all the while ensuring an increasing supply of food. Here we describe the challenges and prospect for typical cropping systems in semi-arid, mesic, and moist conditions. Farmers will need to manage inputs, and improve practices that will ensure long term productivity of the soil and this includes adding diversity to fields, farms, and landscape. The future for cropping systems is favorable provided that there is improving technology and field practices along with enlightened policies in all parts of the world.

Determination of Ammonia Emission Factors for Land Application of Poultry Manure

Ammonia (NH3) emissions from farm operations have been identified by the National Agri-Environmental Health Analysis and Reporting Program (NAHARP) as one of the quantitative indicators of agricultural environmental performance in Canada. Based on current estimates, about 6% of all Canadian emissions can be attributed to land application of poultry manure. The Fraser Valley of B.C. generates large quantities (approximately 280,000 tonnes) of poultry manure each year. While land application of poultry litter can provide essential plant nutrients for crop production, improper manure management can lead to ammonia volatilization from the litter, and it can be detrimental to the environment.