No abstract

Synopsis K application increased dry‐matter yields, K content, P and K uptake, and recovery of applied P, tended to increase the Ca/Mg ratio and sum of cations, reduced leaf spot infection, and tended to reduce N, P, Mg, and Ca content. Forage contained very high Mg and low Ca producing a low Ca/Mg ratio. Second clipping forage contained more Ca and Mg and less K than did the first clipping. Spring K application increased K content and uptake and tended to reduce incidence of leaf spot as compared to fall K application.

Synopsis Ammonium nitrate, ammonium sulfate, and calcium nitrate were equally effective as nitrogen sources but urea was seldom as effective. Anhydrous ammonia and calcium cyanamide were inferior to all other carriers. Split applications spread yields out over 2 and 3 cuttings but produced no higher yields for the entire season than did the same amount of nitrogen applied only in the spring. Spring nitrogen applications generally were superior to equal quantities applied in the fall.

No abstract

Domestic grasses are difficult to establish and maintain in the Caribou Hills of the lower Kenai Peninsula in Alaska. Thus this 8‐year study sought to determine native bluejoint [Calamagrostis canadensis(Michx.) Beauv.] response to varying N, P, and K fertilization rates applied annually and stand persistence when two cuttings were made each growing season. A 4 × 22factorial experiment with four N rates (67,134,201, and 268 kg N/ha) and two P and K rates (84 and 168 kg P/hq 93 and 186 kg K/ha) was established on Kachemak silt loam (thixotropic over loamy, mixed Typic Cryandept) at 366 m elevation. Concentrations of NO3−N, total N, P, K, S, Ca, Mg, and Si in the plants were determined and uptake of these constituents calculated, During this 8 years with two annual harvests and with fertilization the bluejoint stand became more dense. Each increasing N rate through 134 kg/ha generally increased the annual yield. Concentrations of N03−N and total N in both cuttings and annual N uptake were increased by each increasing N increment while the Si concentration of each cutting was depressed. Significant yield interaction between N and K occurred with greater response to N or K at the higher rates of the other. Application of P increased forage yield, P, Ca, and Mg concentrations, and P, K, S, Ca, and Mg uptake. Doubling the P rate further increased these values. Potassium application increased yield, K concentration, and P, K, and S uptake. Doubling the K rate increased the yield at higher N rates and decreased Ca, Mg, and Si concentrations and uptake. Ranchers in the lower Kenai Peninsula area of Alaska can now be assured native bluejoint can be the most important forage grass to provide supplemental winter livestock feed. Persistent high yields can be maintained with less cost than with any other presently known forage.