The Growth Response of Young Jack Pine to Nitrogen and Phosphorus
N as urea at rates of 0 and 100 kg/ha and P as triple superphosphate at 0, 200, and 400 kg/ha were applied to 5-year-old jack pine growing in a well-drained, sandy, orthic humo-ferric podzol. The urea was broadcast, but two types of application were made for the P: it was either broadcast or placed in the soil about each tree. One half of each plot received herbicide treatment. Tree measurements and foliage sampling were made later in the year of treatment and also during the next year. Fertilizer treatments increased the needle weight of foliage produced in the treatment year but did not affect height. Simazine–paraquat herbicide reduced height growth the year after treatment. From the changes in nutrient concentrations it is argued that K is a most likely limiting nutrient.