ISSN:
1435-0661
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Medicago sativa L.) usually obtains a high percentage of its required N via symbiotic N fixation, additional fertilizer N applied once in the spring can increase forage yields. However, little is known about alfalfa yield response to low N rates (〈50 kg N ha−1) immediately following each cutting. Low N rates (immediately following each cutting) were evaluated for total alfalfa dry matter production on a Grant silt loam (fine-silty, mixed, thermic, Udic Argiustoll). This nonirrigated experiment was initiated on a 2-yr-old alfalfa stand where sufficient P and K had been applied. Nitrogen rates of 11, 22, and 44 kg N ha−1 were applied immediately following each cutting for 5 yr (4–5 cuttings yr−1). After 5 yr of continuous N application, no differences in soil NH4–N or NO3–N were found at depths 〉15 cm (0- to 240-cm sampling depth). In 1994, total alfalfa dry matter yield (sum of five harvests) increased 1.29 Mg ha−1 from a total annual N application of 110 kg N ha−1 (22 kg N ha−1 following each cutting). Total forage N decreased from the second to the fifth harvest in most years. By-harvest dry matter yield increases due to applied N were only found in late-season harvests, consistent with late-season decreased N2-fixing capacity in alfalfa documented by others.
Type of Medium:
Electronic Resource
