The presidedress nitrate test (PSNT) is currently the best tool available for Northeastern producers to determine if corn (Zea mays L.) will benefit from sidedress N. The PSNT requires 0-to 30-cm soil samples, which can be difficult to obtain on stony soils, and samples need to be taken in late-spring, an inopportune time for dairy (Bos taurus) farmers. Additionally, the in-season nature of the PSNT prevents its use by producers who apply preplant broadcast N. The Illinois soil N test (ISNT) is a simple test that estimates a potentially mineralizable fraction of soil organic N, amino sugar N. The test was able to identify sites that are nonresponsive to sidedress N fertilization in Illinois. From 2002 to 2004, 33 field trials were conducted to assess the effectiveness of the ISNT as compared with the PSNT in New York. Results confirmed the ability of the PSNT to separate responsive from nonresponsive corn sites. The ISNT was not an effective predictor by itself. However, when ISNT results and soil organic matter (OM) were considered, critical values could be developed that separated fields that were responsive to sidedress N from nonresponsive sites for corn silage dry matter yield, N concentration, N uptake, and estimated milk yield (kg of milk per ha predicted based on yield and quality of the silage). Further evaluation of the ISNT with consideration for OM could improve the accessibility of soil N testing to corn producers who apply N as sidedress as well as those who fertilize with preplant broadcast applications in the Northeast.

The Illinois soil N test (ISNT) is a simple laboratory analysis that shows promise as a tool to predict if additional N application for corn (Zea mays L.) will result in a yield increase. Initial testing of the method at Cornell University showed a high degree of day‐to‐day and within‐griddle soil test N variability. At the University of Illinois, similar findings led to modification of the method to include jar rotations 1.5 and 3 h after initiation of the 5‐h incubation period used in the test. To determine if variability could be reduced without additional labor by enclosing the griddles using plywood boxes, experiments were designed to compare soil test variability using both the open‐bench and enclosed‐griddle methods. Enclosing the griddles decreased the coefficient of variance (CV) (p = 0.013) to 2.5% from 3.8% when analyses were done using the open‐bench method (using 10 exterior positions of the griddle for each method). Enclosing griddles did not impact recovery of added glucosamine‐N but resulted in lower N test values when set at the same temperature as the open‐bench griddles. A comparison study of 14 soils analyzed at the University of Illinois using the standard open‐bench procedure with jar rotation and at Cornell University using the enclosed‐griddle method without rotation showed sample means to be comparable when the enclosed griddles were set at 50.6°C. These results imply that the modified method could be adopted for use beyond well‐controlled laboratory environments but that griddle temperature setting is extremely important.

Response of the Illinois Soil Nitrogen Test to liquid and composted dairy manure applications in a corn agroecosystem. Can. J. Soil Sci. 86: 655-663. Dairy manure is important for corn (Zea mays L.) production in New York. Optimizing corn yield while minimizing environmental loss with manure nutrients is often a challenge. A potential tool for improving N management is the Illinois Soil Nitrogen Test (ISNT), which estimates amino sugar N, a pool of potentially mineralizable N for corn uptake. The objectives of this study were to determine (1) the short-term effects of manure applications on ISNT-N, and (2) the longer-term impacts of annual additions of composted and liquid dairy manure on ISNT-N. A 6-wk incubation study showed that NH 4 -N from manure temporarily (< 2 wk) increased ISNT results. A 4-yr field study was conducted with annual spring applications of two rates of composted dairy manure (45 and 77 Mg ha -1 ) and two liquid dairy manure rates (63.5 and 180 kL ha -1 ). Results showed that ISNT-N slightly decreased over time in check plots (no manure or fertilizer additions) and that increases in ISNT-N over time in compost and liquid manure amended plots were consistent with changes in N credits currently given to manures in New York. Our results suggest that the ISNT accounts for N in previously applied compost and manure amendments, but that samples should not be taken within 2-wk following manure addition.

Some growers in northern corn (Zea mays L.) producing regions forgo the typical autumn harvest for various reasons, but not without the risk of significant yield loss. Therefore, strategies are needed for managing the risks to yield when harvesting corn in spring. Field experiments, with various management strategies, were initiated in Ontario, Canada near Belmont and Ridgetown in 2009 and near Belmont, Ridgetown, and Lucan in 2010. Management strategies investigated the use of hybrids with a range in maturity, the use of standard and reduced plant populations, and the use of a foliar fungicide applied around tasseling. The parameters examined were stay-green in autumn, lodging in spring, and grain yield, moisture, and test weight of corn harvested in autumn and spring. Standard corn production practices consist of using a full-season hybrid planted at 80,000 plants•ha −1 with no late-season fungicide application; however, if over-wintered at Belmont, corn managed using these practices resulted in a 23.1% yield loss (12.1 vs 9.3 Mg•ha −1 ) averaged across years when the crop was harvested in the spring. An overwintering management strategy for corn was identified, which consisted of planting at a reduced plant population (60,000 plants•ha −1 ) and spraying the crop with QUILT ® (azoxystrobin + propiconazole at 200 g a.i. ha −1 ) at the VT to R1 growth stage. Averaged across all hybrids, this strategy minimized yield losses through improvements on corn standability with only a 3.5% yield loss at Ridgetown and a 13.2% yield loss at Belmont. Furthermore, grain test weights for corn with the overwintering strategy were similar to or greater than corn overwintered with the standard production practice. However, weather conditions have the potential to overwhelm any management strategy. In spite of the favorable data indicating reduced risks with a spring harvest, lodging was still higher than expected and yield losses would likely be unacceptable for most growers to make a spring corn harvest a widely accepted practice, unless autumn grain moistures are extremely high, drying charges * Corresponding author. K. J. Mahoney et al. 373are high, and if stalk strength going into the winter was exceptional.