Leaching of Soil Calcium, Magnesium, and Potassium in Irrigated Orchard Lysimeters

Abstract

Leaching under intense irrigation and nitrogen fertilization has reduced soil basic cation concentrations and soil pH in irrigated apple orchards. The objective of this study was to measure the effects of N fertilizer and grass cover vs. clean cultivation on Ca, Mg, and K leaching, and to determine the changes in concentrations of these cations in soil and leaf and fruit tissue of ‘McIntosh’ apple trees (Malus domestica Borkh.). Twelve lysimeters, each containing an Osoyoos sandy loam soil and a single ‘McIntosh’ apple tree, have been monitored for Ca, Mg, and K concentration of soil, drainage water, and tree leaves and fruit from 1976 to 1980. Lysimeter treatments included factorial combinations of Kentucky bluegrass (Poa pratensis) and clean cultivation and two N fertilization rates [162 (N1) and 324 kg N ha−1 year−1 (N2) as NH4NO3]. Clean cultivation had the greatest effect on cation leaching with significantly higher Ca and Mg concentrations and higher Ca, Mg, and K losses frequently measured in drainage from these plots. By 1981, exchangeable Ca, Mg, and soil pH at the 0‐ to 0.10‐m soil depth in the cultivated plots had declined by 4.3 mmol kg−1, 2.2 mmol kg−1, and 0.3 units, respectively, relative to the grass plots. Drainage from N2 relative to N1 lysimeters had a significantly higher Mg concentration for 4 years but significantly higher Ca and Mg loss rates in only 1 year because of lack of differences in drainage volumes between N2 and N1 plots. Neither the cultivation or fertilizer treatments had altered Ca, Mg, or K concentration of McIntosh fruit or foliage in 4 years. For all lysimeters, Ca and Mg leached more rapidly than K. Annual losses over all treatments, 1976 through 1980, averaged 387 kg Ca ha−1, 118 kg Mg ha−1, and 44 kg K ha−1. Such leaching would eventually lead to enrichment of local soils with K relative to Mg and Ca. This is undesirable since McIntosh trees are susceptible to Mg deficiency and K:Ca antagonism. Therefore, periodic additions of Ca and Mg as through dolomitic liming should be considered for these orchards. Also, K fertilization accelerates existing trends to relative enrichment of these soils with K.

Nitrogen Additions and Losses to Drainage in Orchard-Type Irrigated Lysimeters

“…The design and operation of the Summerland lysimeters has been described previously (Neilsen and Stevenson 1983 The totals of irrigation water plus precipitation have been reported previously (Stevenson 1989) but for each of the full drainage years (l Oct. to 30 Sept. following) the irrigation plus precipitation received by the lysimeters was 763, 728,760, I l0l, 928, ll4l, 1459, 1750, 1086 mm for years I through 9, respectively (Stevenson 1989 This has been noted and discussed by Avnimelech and Raveh (1976), Walsh (1973), Letey et al (1977), Chang et al (1988), Kowalenko (1978) and Kowalenko and Cameron (1978).…”

“…Nitrogen has also been the subject ofconsiderable concern with respect to N contamination of ground and surface waters (Neilsen et al 1978. ) (Stevenson 1979(Stevenson , 1989Neilsen and Stevenson 1983) addressed the issues ofwater and nutrient losses other than N. This report examines the 9-yr regime of nitrogen inputs and losses.…”

Magnesium deficiency in citrus grown in the Gisborne district of New Zealand

“…It would be useful to compare citrus root distribution and the morphology of citrus root systems in Gisborne soils with those found in better-structured soils elsewhere. leaching may also alter the K:Mg ratio, especially in herbicide strips or after N (nitrogen) or Ca applications (Haynes & Goh 1980;Neilsen & Stevenson 1983). Neilsen & Stevenson (1983) found that proportionally more Mg was leached than K and Ca, compared with their ratios on the CeC.…”

“…leaching may also alter the K:Mg ratio, especially in herbicide strips or after N (nitrogen) or Ca applications (Haynes & Goh 1980;Neilsen & Stevenson 1983). Neilsen & Stevenson (1983) found that proportionally more Mg was leached than K and Ca, compared with their ratios on the CeC. However, leaching of Mg is unlikely to be a significant factor in explaining why Mg deficiency is worse in Gisborne than in other citrus growing regions, because Gisborne soils have a similar or higher CeC (Table 1) and a lower annual rainfall (MetService 2007) than Auckland, Bay of Plenty (Tauranga), and Kerikeri.…”

Irrigation Subsurface Return Flows and Water Use in Lysimeters Containing Apple Trees

“…The lysimeters that were used for this study were described previously (Stevenson 1979;Neilsen and Stevenson 1983 (Stevenson 1979). That occurred at the irrigation level of 37% of design flow.…”