Nitrogen (N) and sulphur (S) are essential nutrients for plant growth. A pot experiment was conducted to verify whether maize and soybean under monoculture and intercropping could utilise N- and S-containing amino acids when competing with soil microorganisms. Maize and soybean were able to utilise methionine (Met; 1.9–2.2% of total addition) and cysteine (Cys; 0.6–1.6% of total addition) as N and S sources, however they faced competition with soil microorganisms. Six hours after microbial uptake, 45.3–64.0% of the S from Met was retained in the microbial biomass, while there was much lower retention from Cys (16.8–34.5%), and 32.5–44.1% of the S from Cys and 15.6–33.3% of that from Met was transformed to SO₄²⁻. Cys was a superior S source for plants compared to Met, as higher SO₄²⁻ release from Cys could support plant growth. Both maize and soybean plants took up NH₄⁺ (98–99% of total N uptake) and SO₄²⁻ (85–90%) as their main N and S sources from soil. The N from Cys and Met accounted for only ~1% of total N uptake from soil, and organic Cys and Met accounted for only ~0.2% of the total N uptake, indicating that these two amino acids have limited effects on plant N nutrition, due to the high inorganic N content in agricultural soil. However, the Cys and Met contribution (i.e., organic S uptake and mineral S uptake originating from Cys and Met) to total S uptake (10–15%) was an order of magnitude higher than their N contributions, suggesting that Cys and Met play an important role in soil S nutrition. Intercropping altered the uptake but not the preference for N and S forms in maize and soybean. Overall, the results suggest that S-containing amino acids are important S sources for plant growth even at a lower concentration in soil, but that they play a limited role in plant N nutrition due to a larger inorganic N pool in agricultural soil.

氮（N）和硫（S）是植物生长必不可少的营养素。进行了盆栽试验，以验证在单作和间作的玉米和大豆与土壤微生物竞争时是否可以利用含N和S的氨基酸。玉米和大豆能够利用蛋氨酸（Met；占总添加量的1.9–2.2％）和半胱氨酸（Cys；占总添加量的0.6–1.6％）作为氮和硫的来源，但是它们面临着与土壤微生物的竞争。微生物吸收后六小时，来自Met的S保留在微生物生物量中的占45.3–64.0％，而来自Cys的保留率则低得多（16.8–34.5％），而来自Cys和S的保留率则低至32.5–44.1％和15.6–来自Met的33.3％转化为SO ₄ ^2-。与Met相比，Cys是植物的优良S来源，因为SO ₄更高半胱氨酸的^2-释放可以支持植物的生长。玉米和大豆植物都吸收NH ₄ ⁺（占总氮吸收的98–99％）和SO ₄ ²⁻（85–90％）作为土壤中主要的N和S来源。半胱氨酸和蛋氨酸的氮仅占土壤吸收氮总量的〜1％，有机半胱氨酸和蛋氨酸仅占土壤氮吸收总量的约0.2％，表明这两种氨基酸对植物氮素营养的影响有限，由于农业土壤中无机氮含量高。然而，Cys和Met的贡献（即，来自Cys和Met的有机S吸收和矿物质S的吸收）对总S吸收的贡献（10-15％）比其N贡献高一个数量级，这表明Cys和Met发挥了作用。在土壤S营养中的重要作用。间作改变了玉米和大豆对氮和硫形态的吸收，但没有改变。总体而言，结果表明，即使土壤中的S含量较低，含S氨基酸也是植物生长的重要S来源，