基于氢氧同位素不同盐肥条件下棉田水分分布研究

Study on water distribution in cotton field based on hydrogen and oxygen isotopes under different salt and fertilizer conditions

棉花是新疆主要农作物,研究不同盐分与肥料处理下利用土壤水分深度及比例情况对合理利用灌溉水,保障棉花提高产量具有重要意义。试验以“新路早48号”棉花为研究对象,设置3种盐分梯度土壤:3、6、9 g·kg^(-1)(S1、S2、S3);3种施肥梯度土壤(以氮计):105、210、315 kg·hm^(-2)(N1、N2、N3)。基于氢氧同位素示踪法,分析不同盐分和肥料处理的膜下滴灌棉花土壤水与茎秆水氢氧同位素组成特征,利用IsoSource模型分析棉花在不同处理下影响各层土壤水利用比例。结果表明,棉花在每个生育期不同处理下主要利用土壤水分比例最大值分别为苗期0~20 cm N1S3(79%),蕾期20~40 cm N2S3(57.5%),花期40~60 cm N3S1(63.7%),吐絮期40~60 cm N3S1(80.3%)。随盐分与肥料变化,棉花调整利用土壤水的比例结构。苗期与蕾期,当盐分为S1和S2时,随施肥量增加棉花对0~40 cm土壤水利用比例逐渐降低。当盐分为S3时,棉花对于0~40 cm土壤水吸收比例关系为N2S3>N1S3>N3S3。花期与吐絮期棉花对于40~60 cm土壤水利用规律与前两个生育期利用0~40 cm土壤水规律相同。研究可为新疆干旱区棉花科学灌溉提供理论依据。

Cotton is the main crop in Xinjiang. Studying the depth and proportion of soil water under different salt and fertilizer treatments is of great significance for the rational use of irrigation water and ensuring the increase of cotton yield. Taking "Xinluzao 48" cotton as the research object. The soil with three salt gradients was tested: 3, 6, 9 g·kg^(-1)(S1, S2, S3);soil with three fertilization gradients(calculated by nitrogen): 105, 210, 315 kg·hm^(-2)(N1, N2, N3). Based on the method of hydrogen and oxygen isotope tracing, the hydrogen and oxygen isotope composition characteristics of cotton soil water and stem water under film drip irrigation with different salinities and different fertilizer treatments were analyzed, and the proportion of water utilization of each layer of soil by cotton under different treatments was analyzed by IsoSource model. The results showed that under different treatments at each growth stage, the maximum proportion of soil water used by cotton was N1S3(79%) at 0^(-2)0 cm at seedling stage, N2S3(57.5%) at 20-40 cm at bud stage, N3S1(63.7%) at 40-60 cm at flowering stage,and N3S1(80.3%) at 40-60 cm at boll opening stage. At seedling stage and bud stage, when the salinity was S1 and S2, the proportion of water use of cotton to 0-40 cm soil gradually decreased with the increase of fertilizer application. When the salt content was S3, the absorption ratio of cotton to 0-40cm soil water was N2S3>N1S3>N3S3. The utilization law of 40-60 cm soil water of cotton in flowering and boll opening stages was the same as that of 0-40 cm soil water in the first two growth stages. The conclusion could provide a theoretical basis for scientific irrigation of cotton in arid areas of Xinjiang.