Eight field-plot experiments were carried out on established grassland swards between 1984 and 1988 to examine the effects of date and rate of application of calcium ammonium nitrate (CAN) on herbage dry matter (DM) yield and apparent efficiency of nitrogen (N) use at firstcut silage.CAN application significantly increased (P<0-001) the mean yields of herbage and N uptakes by herbage in all experiments. Herbage yields were similar (P>0-05) with N rates of 100 kg ha"', 125 kg ha"' or 150 kg ha"' in five experiments but in the other three there were increases above 100 kg ha''. Date of N application had a'significant effect on DM yield in three experiments; this effect was inconsistent for both single and split dressings. Lower production was associated with reduced uptake of N, a trend that primarily refiected lower DM yields and not wide herbage N content variation.It is concluded that selection of the date on which to apply fertilizer N in early spring to obtain optimum herbage yields at first-cut silage often required little precision. The use of fertilizer N rates >100 kg ha'' should be questioned where there are likely to be appreciable quantities of available N derived from non-fertilizer sources.
The effects of forage maltifig on rate of grass drying and silage fermentation, digestibility, and intake were examined using perennial ryegrass swards. Treatments compared were: forage mats, where grass was processed through a laboratory scale macerator prior to matting and willing to 228 g dry matter (DM) kg"' (FM treatment); unconditioned grass which was direct ensiled at 163 g DM kg"' (DE treatment); unconditioned grass which was wilted for the same period as FM to 213 g DM kg"' (UC treatment); unconditioned grass which was wilted to 234 g DM kg"' (UCj, treatment). All forages were dned on black plastic sheeting. For each treatment a total of approximately 80 kg grass DM was ensiled in seven 290 I plastic bins for 136 d prior to feeding to wetber sheep. A further total of 14 kg grass DM from each treatment was ensiled in twetity-one plastic pipes (152 mm diameter, 762 mm long) to give a total of 84 pipes. Rate of silage fermentation was determined by destructively sampling pipes following 1, 2, 4, 6, 13, 20 and 50 d of ensilage. Over the mean wilting period of 6'9 h, grass from the FM treatment dried significantly faster (P < 0 001) and required less solar energy per unit of moisture loss than unconditioned grass. The rate of grass drying was highly correlated with solar radiation. Tbe FM treatment did not influence the rate or extent of silage fermentation. The intakes and digestibilities of FM, UC and UCT5 ^"^ ""^^ significantly {P < 0 05) different from each other but were higher than for the DE treatCotTespondetice; J.P. Frost. The Agnculitiral Research InsliluLe ofNotthem Ireland. Hiilsborough, Co. Down, BT26 6DR. UK. ment (P < 0 05 for digestibility and NS for intake). In Nonhem Ireland it is unlikely that there will be sufficient solar radiation to allow forage mats to be made, wilted to a level to prevent etfluent production and barvested witbin one working day. Funher work is required to optimize mat-making technology for more rapid drying and to determine the effect of adverse weather on nutrient losses from mats.
An experiment was carried out during 1986 and 1987 to examine the effects of mid-season slurry injection and fertilizer-nitrogen (N) application on herbage dry matter (DM) yield and N recovery. Cattle and pig slurry were injected at 56 and 112 m' ha " ' into an established sward. Five rates of fertilizer-N, as calcium ammonium nitrate, ranging from 0 to 120 kg ha"' in 30-kg increments, were superimposed on these treatments, and in both years DM yield was measured in one cut after 70 d regrowth. Slurry treatments increased herbage DM yields significantly (P<0-001). Theefficiency of slurry total N compared with calcium ammonium nitrate-N averaged 53% in 1986 and 86% in 1987. The mean apparent recovery of slurry total N in herbage was 55% in 1986 and 40% in 1987. Fertilizer-N application increased (P < 0 • 001) the mean yields of herbage in both years but when combined with some of the slurry treatments, DM yields over the five N-Ievels did not differ significantly, giving rise to interactions in 1986 (P<0-001) and 1987 (P<0 01). It is concluded that mid-season injection of slurry can be an effective means of utilizing slurry-N in terms of herbage DM production and consequent N use.
A field plot experiment was carried out on an established grassland sward from 1983 -88 inclusive to examine the effects of time of application, chemical form of nitrogen (N) and cattle slurry dry matter (DM) content on yield and efficiency of N use.
These demonstrations and replicated studies provide information that can be used by Virginia corn growers to make better management decisions on their farm. These results should be used along with data from other replicated studies when making decisions. Refer to individual location results for additional detail. Hybrid ComparisonsCorn hybrid selection remains a challenge for Virginia producers. With more seed companies, and more GMO options and seed treatment packages than ever before, hybrid selection can be a difficult decision.We evaluated early maturity hybrids (107 day RM or less) at five locations, mid maturity hybrids (108-112 day RM) at seven locations, and full season hybrids (113 day RM or more) at nine locations.Hybrids from all three maturity groups were planted at both the 2020 Virginia Ag Expo site located in Northumberland County and Virginia State University. Farmers should use the results compiled from these studies to assist with future hybrid selection; however, they should continue to plant hybrids of multiple maturities to help spread production risk. Cover Crop EvaluationWe continue to evaluate legume and cover crop options in corn production. Our work continues to demonstrate that legume cover crop options can provide significant nitrogen to the subsequent corn crop. Hairy vetch and Austrian winter pea, in particular, show great promise in increasing Virginia corn yields.
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