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依托祁阳红壤旱地定位施肥试验(始于1990年),选取施氮磷(NP)、氮磷+石灰(NPCa)、氮磷钾(NPK)、氮磷钾+石灰(NPKCa)、氮磷钾配施秸秆(NPKS)、氮磷钾配施秸秆+石灰(NPKSCa)6个处理,采集玉米不同生育期根际与非根际土壤,测定其钾、钙、镁、铝含量和p H。结果表明:与NP处理相比,施钾处理(NPK和NPKS)根际和非根际土壤速效钾含量显著提高。NP、NPK和NPKS处理根际速效钾在拔节期和灌浆期均处于亏缺状态,亏缺率分别平均为18.2%、34.2%和26.4%。与对应不施石灰处理相比,NPKCa和NPKSCa处理根际土壤速效钾含量在苗期分别降低46.0 mg kg-1和26.5 mg kg-1,非根际分别降低68.5 mg kg-1和56.0 mg kg-1;从拔节期至收获期,根际速效钾含量平均升高25.2 mg kg-1和33.7mg kg-1,非根际略微降低。NPCa、NPKCa和NPKSCa处理根际土壤速效钾盈亏率与不施石灰相比,整个生育期分别平均提高8.6%、33.2%和19.3%。根际和非根际土壤速效钾含量与相对应缓效钾含量、钾饱和度、K+/(Ca2++Mg2+)和K+/Al3+呈极显著正相关关系。缓效钾和钾饱和度相对变化率(交换性钙镁相对变化率)与速效钾相对变化率呈极显著正(负)相关关系。长期施氮磷钾肥基础上施石灰(NPKCa和NPKSCa)4年以后,根际土壤速效钾、缓效钾含量及钾饱和度均提高(苗期除外),根际土壤交换性钙镁含量提高幅度低于非根际,最终缓解根际土壤钾素的亏缺。
Based on the fertilization experiment of red soil in Qiyang Red soils (started in 1990), NP, N, P, NPK, NPK and NPK NPKS and NPKSCa were applied to treat rhizosphere and non-rhizosphere soils at different growth stages of maize. Potassium, calcium, magnesium and aluminum contents and p H were determined. The results showed that the contents of available potassium in rhizosphere soil and non-rhizosphere soil were significantly increased as compared with NP treatment. NP, NPK and NPKS treatments were in a deficit state at the jointing and filling stages, with an average deficit rate of 18.2%, 34.2% and 26.4%, respectively. Compared with non-lime treatment, NPKCa and NPKSCa decreased rhizospheric soil available potassium by 46.0 mg kg-1 and 26.5 mg kg-1 at the seedling stage and by 68.5 mg kg-1 and 56.0 mg kg-1 at the non-rhizosphere soil -1. From the jointing stage to the harvesting stage, the available potassium in rhizosphere soil increased by 25.2 mg kg-1 and 33.7 mg kg-1 on average, while the non-rhizosphere soil slightly decreased. Compared with no lime treatment, the profitability of available potassium in rhizosphere soil of NPCa, NPKCa and NPKSCa increased by 8.6%, 33.2% and 19.3% on average during the whole growth period respectively. The contents of available potassium in rhizosphere soil and non-rhizosphere soil were significantly and positively correlated with the contents of slow potassium, potassium, K + / (Ca2 + + Mg2 +) and K + / Al3 +. The relative rate of change of slow potassium and potassium saturation (relative change rate of exchangeable calcium and magnesium) and the relative rate of change of available potassium showed a significant positive (negative) correlation. After 4 years of application of NPKCa and NPKSCa, the content of available potassium, slow-acting potassium and potassium in the rhizosphere increased (except in the seedling stage), and that in the rhizosphere soil increased by exchange of calcium and magnesium Below the non-rhizosphere, and eventually alleviate the deficit of potassium in rhizosphere soil.