Long-term Response to Phosphorus Banding in Irrigated and Nonirrigated Pecan Production

Abstract

<jats:p>An experiment was conducted to determine the effects of banded phosphorus (P) applications at differing rates in irrigated and nonirrigated pecan (<jats:italic>Carya illinoinensis</jats:italic>) plots on P movement within the soil, P uptake and movement within pecan trees, and the yield and quality of nuts. On 20 Mar. 2015, P applications of 0 kg·ha<jats:sup>−1</jats:sup> (0×), 19.6 kg·ha<jats:sup>−1</jats:sup> (1×), 39.2 kg·ha<jats:sup>−1</jats:sup> (2×), and 78.5 kg·ha<jats:sup>−1</jats:sup> (4×) were administered to bands of triple superphosphate to randomly selected trees in nonirrigated and irrigated plots of a ‘Desirable’ orchard bordered by ‘Elliot’ trees. When P was applied at the 2× and 4× rates, the total soil test P decreased linearly by 35% and 54%, respectively, in nonirrigated plots and by 41% and 59%, respectively, in irrigated plots over the course of the experiment. There was no change in soil test P over time at the 0× rate for either irrigation regimen; however, at the 1× rate, soil test P decreased 44% in the irrigated plot but did not change in the nonirrigated plot. The largest linear decrease of the soil test P from the start of the experiment to the end of the experiment occurred in the top 0 to 7.6 cm. In contrast, soil test P at a depth of 15.2 to 22.9 cm decreased linearly by 23% in the nonirrigated plot, but it did not decrease over time in the irrigated plot. Increasing the P application rate increased foliar P quadratically in the nonirrigated plot, but only the 4× application rate increased foliar P compared with the 0× control. In the irrigated plot, foliar P concentrations decreased linearly from 2015 to 2017, and foliar P concentrations were not influenced by the P application rate. No differences in pecan yield or quality were observed in either irrigated or nonirrigated plots. Overall, P banding may not be the most sustainable way to increase foliar concentrations of P quickly or to maintain concentrations of the nutrient in the long term.</jats:p>

Phosphorus Fertilization Can Improve Young Almond Tree Growth in Multiple Replant Settings

“…Leaves displaying P deficiency symptoms were rare in commercial orchards (Brown and Uriu 1996;Cullinan and Batjer 1943;Overcash et al 1960), suggesting that orchards were seldom P-deficient. The P fertilization trials in bearing orchards often demonstrated little to no response in yield (Klein et al 1999;Polozola et al 2019), although increased leaf P levels were sometimes measured (Ferreira et al 2018;Leece 1976). It was stated that there is no reason to apply P fertilizer to almond (Prunus amygdalus) orchards other than to supply the needs of a cover crop (Carlson 1996).…”