Biochar Affects Essential Nutrients of Carrot Taproots and Lettuce Leaves

Abstract

<jats:p>Essential nutrient concentrations in crops can affect human health. While biochar has the potential as a soil amendment to improve crop yields, it may also affect the concentrations of nutrients such as Ca, Fe, K, Mg, Mn, and Zn in edible portions of crops. To better characterize effects of biochar on important human nutrients in food crops, we evaluated the effects of biochar on lettuce (<jats:italic>Lactuca sativa</jats:italic> L. cv. Black-Seeded Simpson) leaf and carrot [<jats:italic>Daucus carota</jats:italic> subsp. <jats:italic>sativus</jats:italic> (Hoffm.) Schübl. cv. Tendersweet] developing taproot nutrients. Plants were grown in pots in a greenhouse using sandy loam (Coxville, fine, kaolinitic, thermic Typic Paleaquults) and loamy sand (Norfolk, fine-loamy, kaolinitic, thermic Typic Kandiudults,) series soils, amended with biochar produced from four feedstocks: pine chips (PC), poultry litter (PL), swine solids (SS), and switchgrass (SG); and two blends of PC plus PL [PC/PL, 50%/50% (55) and 80%/20% (82) by weight]. Biochar was produced at 350, 500, and 700 °C from each feedstock. Lettuce leaf and carrot taproot total nutrient concentrations were determined by inductively coupled plasma analysis. Biochar (especially at least in part manure-based, i.e., PL, SS, 55, and 82 at nearly all temperatures) primarily decreased nutrient concentrations in lettuce leaves, with Ca, Mg, and Zn affected most. Carrot taproot nutrient concentrations also deceased, but to a lesser extent. Some biochars increased leaf or taproot nutrient concentrations, especially K. This study indicated that biochar can both decrease and increase leaf and taproot nutrient concentrations important for human health. Thus, potential effects on nutrients in plants should be carefully considered when biochar is used as a soil amendment with vegetable crops.</jats:p>

Biochar affects growth and shoot nitrogen in four crops for two soils

“…The Norfolk soil N concentration was below the level of detection. The PL, 55, and 82 biochars had similar but higher pH levels than the SS, PC, and SG biochars (Table 2) (Olszyk et al., 2018, 2020). The SS biochar had the highest N, Ca, Mg, and P concentrations, followed by the PL, 55, and 82 biochars, in descending order.…”

“…The finer‐textured loamy sand Coxville soil had a lower pH, higher K and P concentrations, and much higher organic C than the coarser‐textured sandy loam Norfolk soil (Table 1) (Olszyk et al., 2018, 2020; Sigua et al., 2014). The Norfolk soil N concentration was below the level of detection.…”

“…Therefore, the objectives of this study were to fill these knowledge gaps by (a) determining the effects of a variety of different biochars on crop productivity using four important crops grown under similar greenhouse conditions, (b) determining the effects of soil type on biochar responses, and (c) determining not only growth responses but also effects on N, a major plant nutrient. Sigua et al (2014), Olszyk et al (2018Olszyk et al ( , 2020. The K, P, Ca, Mg, Zn, Cu, Mn, B, and Na data are based on a Mehlich 1 extraction solution (J.…”

“…The uppermost horizon (∼0-23 cm) of both soil profiles was use in this study. Site cultivation history, crop management, and additional characteristics of the soils are described elsewhere (Novak et al, 2014;Olszyk, Shiroyama, Novak, & Johnson, 2018;Olszyk et al, 2020;Sigua et al, 2014) and are summarized in Table 1. After collection, both soils were air-dried and sieved.…”

“…Key chemical characteristics of the biochars used in this study are shown in Table 2. Data are based on Novak et al (2013Novak et al ( , 2014, Olszyk et al (2018Olszyk et al ( , 2020, and J. Novak (personal communication, 2016Novak (personal communication, , 2020.…”