On-Farm Research Publications
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Factors Affecting Nitrogen Availability and Variability in Cornfields.
- N application rate for corn should be estimated conditional to other influential factors to N availability.
- Guided sampling by aerial imagery for end‐of‐season stalk nitrate‐N test is a useful tool to benchmark N variability.
- N availability for corn is significantly affected by crop rotation, tillage, soil, and N form, rate, and timing.
Nitrogen management in corn (Zea mays L.) is complicated by uncertainties in the agro‐ecological system. Consequently, current N recommendation systems provide accurate estimates of average N rates to apply across geographic regions but not to individual fields. To improve N use efficiency (NUE) and reduce negative environmental impacts, field‐specific N rates should be estimated using site factors that can have significant effects on N loss and availability. We surveyed 920 cornfields across the US Corn Belt and collected 3680 cornstalk samples during a 7‐yr period, 2008 to 2014. Aerial images of the corn canopies taken in late August were used to randomly select three sampling areas within three predominant soil types in each field. Cornstalk samples were evaluated for N status using the end‐of‐season cornstalk nitrate test (CSNT). We also collected data about site‐specific environmental conditions and management practices that had the potential to influence N loss and availability. Ordinal logistic regression (OLR) analysis was used to identify factors that significantly affected cornstalk N‐sufficiency levels, based on the CSNT. Results suggest that N rate alone is not a driving factor that influences N availability to a corn plant during the growing season. Rather, N rate recommendations should be estimated considering other site factors, including rainfall, previous crop, tillage practice, soil drainage class, and N form and timing. Our research findings are useful to support a field‐based adaptive management program and the 4Rs of Nutrient Stewardship management.
Winter Canola Response to Soil and Fertilizer Nitrogen
Winter canola (WC) offers not only marketable products but also excellent rotational benefits through disease, weed, and pest control in the dryland cropping systems of the inland Pacific Northwest (iPNW). However, little regional fertility research has been conducted on WC. The objectives of this study were to (i) determine the influence of soil N supply and fertilizer N rate and timing effects on WC yield in four iPNW agroecological classes and (ii) evaluate how N availability and fertilizer N application timing affect WC seed quality. Earn 1 CEU in Nutrient Management by reading this article and taking the quiz at www.certifiedcropadviser.org/education/classroom/classes/780.
Analyzing the Implementation of Nutrient Management Plans by Farmers: Implications for Extension Education
We conducted case studies on four Connecticut dairy farms to evaluate how well farmers implemented their nutrient management plans (NMPs). Our findings can help Extension educators develop programs to improve NMPs and NMP adoption by farmers. We identified three educational topic areas that would likely increase NMP understanding and acceptance: (a) soil testing protocol, results interpretation, and nutrient recommendations; (b) manure fertilizerequivalent value, proper application, and effective distribution; and (c) costs and benefits of substituting on-farm manure for purchased commercial fertilizer. A new adaptive nutrient management program presents a timely opportunity for cost-effective and collaborative on-farm education efforts by Extension and the Natural Resources Conservation Service.
Nitrogen Inhibitors: How do they work to reduce N Losses
Applying nitrogen (N) fertilizer at the exact time of need is often operationally unrealistic for wheat growers in Washington. Instead, N is commonly applied early, before its rapid uptake by plants. However, this practice may result in reduced return on investment and increased environmental risks associated with N loss through runoff, leaching, volatilization, and denitrification. Nitrogen inhibitors are products that temporarily retard conversion of fertilizers to the forms that can be lost through these pathways. This publication describes how N is lost after fertilizer applications, how N inhibitors can reduce such losses, and how to choose the right product for the forms of your fertilizers and application timings.
End-of-Season Corn Stalk Nitrate Nitrogen Test For Post- Harvest Evaluation
Sufficient supply of nitrogen (N) plays a key role in corn productivity and profitability. Excess nitrogen application wastes farmers’ money, increases the risk of groundwater and surface water contamination, and contributes to greenhouse gas emissions. Evaluating N management is important for farmers to fine tune N management practices to achieve optimum corn yield and environmental sustainability. The end-of-season corn stalk nitrate-nitrogen test and corn yield are well correlated, which provides the basis for post-harvest evaluation of N sufficiency level.
Wheat Straw Pulping By-Product Mixed With Lime May Address Soil Acidification In No-Till Fields
Soil acidification has become a growing concern for dryland crop production in the Pacific Northwest (PNW). Many no-till (NT) soils have stratified soil pH in the fertilizer application zone due to repeated nitrogen (N) fertilizer applications. The practice of liming to correct low soil pH is less effective for stratified soil acidity in no-till systems because lime is relatively insoluble. Consequently, without tillage, the vertical movement of surface-applied lime to the most acid-affected depths (generally 4–12 inches) can take many years. We conducted a greenhouse study to determine whether mixing lime materials with lignin-containing black liquor, a by-product from the pulp industry, offers a viable solution for soil acidity in no-till systems. Results indicate that the lime-black liquor mixture can expedite downward movement of lime and correct stratified soil pH in a short period of time. At 42 days after liming, the super fine micro lime-black liquor mixture increased soil pH from the soil surface to a depth of 6 inches. After 147 days, this finer mixture increased soil pH in the 10–12 inches depth, and the coarser agricultural lime-black liquor mixture increased soil pH from the surface to a depth of 10 inches.
End of Season Corn Stalk Nitrate-Nitrogen Test for Post Harvest Evaluation -- A Case Study
Land application of dairy manure to cornfields is a common practice and a major method of manure disposal for dairy operations. Dairy manure provides numerous benefits for corn and other silage crops. However, excess applications of dairy manure can have negative impacts when nitrogen (N) is lost from the agricultural fields to the environment. Public concerns about pollution of groundwater, surface water, and drinking water have motivated dairy farmers and other stakeholders to explore strategies for fine-tuning dairy manure applications. The end-of-season corn stalk nitrate-N test (CSNT) is a proven and reliable post-harvest evaluation tool for both silage corn and grain corn production under both rain-fed and irrigated.