Differences between soybean genotypes in physiological response to sequential soil drying and rewetting

Short term incubations (4 d) were conducted to assess the effect of a wetting/drying cycle on atrazine sorption, as well as biodegradation, as a function of various atrazine concentrations (ca. 5, 10, and 25 μg g−1soil) and levels of added crop residues (0, 5, and 10% cornstalks by weight), using a technique that allowed independent analysis of soluble and sorbed atrazine. Soil solution atrazine concentrations decreased, and KdSincreased with increasing crop residues. The sorptive capacity of cornstalks for atrazine was estimated to be 860 μg g−1vs 28 μg g−1for unamended soil. Drying and rewetting resulted in lower soil solution concentrations and decreased extraction efficiencies (13 to 22%) for sorbed atrazine; the effect was most pronounced with added cornstalks. High recoveries of14C from soils (combustion data) indicated that atrazine was not lost to volatilization. Rapid rates of biodegradation were observed in cornstalkamended soils shortly after rewetting; degradation was not observed in unamended soil. A longer incubation (6 wk) was conducted with ca. 10 μg g−1atrazine and 5% cornstalks to assess metabolites and kinetics of biodegradation. Atrazine disappearance was observed after ca. 2 wk with concomitant production of deethyl- and deisopropyl-atrazine at a ratio of ca. 2:1. Dealkylated-atrazine accumulated after ca. 3 wk; there was no evidence for hydroxy-atrazine production. These data suggest that biodegradation may play an important role in atrazine losses in the field despite wetting/drying cycles. In addition, there may be apparent losses of atrazine due to decreased extraction efficiencies as a consequence of wetting/drying cycles, resulting in underestimation of field residues.

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The effects of soil drying and rewetting history on phosphorus solubilisation and growth of maize (Zea mays) under contrasting agricultural soils in China

10.5194/egusphere-egu2020-19920 ◽

2020 ◽

Author(s):

Nyamdavaa Mongol

Keyword(s):

Zea Mays ◽

Growth Response ◽

Plant Biomass ◽

Agricultural Soils ◽

Previous History ◽

Soil Drying ◽

Olsen P ◽

P Concentration ◽

Drying And Rewetting ◽

History Of

The effects of soil drying and rewetting history on phosphorus solubilisation and growth of maize (Zea mays) under contrasting agricultural soils in ChinaNyamdavaa Mongol1,2, Jianbo Shen2, Philip M. Haygarth1&#160;1Lancaster Environmental Centre, Lancaster University, Lancaster, LA1 4YW, United Kingdom.2Department of Plant Nutrition, China Agriculture University, Key Laboratory of Plant-Soil Interactions, Beijing 100193, PR China&#160;AbstractThis paper tested the hypothesis that agricultural soils with a recent history of drying and rewetting (DRW) can trigger P solubilisation in the rhizosphere and a subsequent growth response of maize (Zea mays).&#160; Specifically, it aimed at investigating a possible delayed effect of soil DRW stresses by studying P solubilisation in the rhizosphere, plant P acquisition and performance, and root growth, all under the previous history of series of DRW events, combined with different types of agricultural soils of varied texture and pH. &#160;The soils were collected from four different agricultural regions of China, Shandong, Chongqing, Heilongjiang and Beijing, treated with four varying cycles of DRW events prior to the experiment, to raise levels of soil biotic and abiotic activities and potential development of maize growth. A controlled small pot experiment was conducted to establish the Olsen P in the soil, maize shoot P concentrations, root morphology and other rhizosphere parameters, for the duration of 43 days after planting. &#160;&#160;The results show a positive relationship between plant biomass, plant P concentration, and Olsen P. The effect was most clearly demonstrated by growth of plants and their biological performance in the rhizosphere, as the plants responded better in the soil with a DRW background than a soil that did not have a history of DRW in the past.&#160; However, the soluble P concentration and plant growth response varied depending on soil types and P application rates, and the most positive was under Haplic Phaeozems soil from Heilongjiang, leading to an acceptance of hypothesis. &#160;&#160;

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