Site Preparation and Fertilization Effects on Growth of Slash Pine for Two Rotations

Two replicated site preparation studies were used to examine the effect of management on pine height and volume growth in the next rotation on Paleudults. Treatments included no tillage, flat disking, bedding, and fertilization. The first rotation of planted slash pine (pinus ellionii Engelm. var. dioftii) was measured for 15 yr on one site and 20 yr at the other, harvested, and replanted without additional tillage. The second rotations were measured for 10 yr. At one site, 100 kg ha-’ P was applied to each rotation as a treatment variable. At one site, disking before the first rotation increased pine heights. Bedding before the first rotation increased pine heights at both sites. In the second rotation, the response was reversed, with pines planted on beds being the shortest. The P fertilization increased heights in both rotations hut did not affect response to tillage. ‘Ike P as well as N, applied only at age 7 in the second rotation, had a negative effect on the second rotation’s volume, probably hecause of increased competition from shrubs and other understory plants. Across both sites and for all treatments, IO-yr-old slash pines averaged 7% less in height and 24% less in volume in the second rotation. These differences are statistically significant. Analysis at age 10 from both rotations indicates stable foliar concentrations of P and Ca, declining K, and increasing