ABSTRACT

The current experiment envisages estimating nitrification and elucidates the mechanistic processes of nitrogen mineralization in a long-term fertilizer experiment (LTFE) on a soybean-wheat cropping system. The experiment had four treatments: fallow (no fertilizer and no crop), control (no fertilizer), inorganic (recommended dose as 100% NPK), and integrated (100% NPK + farmyard manure FYM). The potential nitrification rate (PNR) estimated as µg NO₃⁻ produced g⁻¹ soil d⁻¹ was 0.88 in fallow, 1.86 in control, 1.278 in 100% NPK, and 1.493 in 100% NPK + FYM. Real-time PCR quantification of bacterial amoA gene (× 10⁴ amoA gene copies g⁻¹ soil) was 19.33 in fallow, 43.33 in control, 30.33 in 100% NPK, and 29.33 in 100% NPK + FYM. The amoA gene copies (x 10⁴ gene copies g⁻¹ soil) of archaea ranged from 11.67 to 38.67. The X-ray diffraction (XRD) of soils indicated that the intensity of the NH₄⁺ minerals was highest in control and lowest in fallow. Soybean grain and biomass yields were highest in 100% NPK + FYM and lowest in control. The study highlights that continuous cropping without fertilizer may alter soil microbial metabolism for the acquisition of nitrogen from mineralization of readily unavailable mineral fractions.

摘要

目前的实验设想在大豆-小麦种植系统的长期施肥实验 (LTFE) 中估计硝化作用并阐明氮矿化的机制过程。试验有4个处理：休耕（不施肥不作物）、对照（不施肥）、无机（推荐剂量为100% NPK）和综合（100% NPK+农家肥FYM）。_{以 µg NO 3} ^-产生的 g ^-1土壤 d ^-1估计的潜在硝化率 (PNR)在休耕时为 0.88，在对照中为 1.86，在 100% NPK 中为 1.278，在 100% NPK + FYM 中为 1.493。细菌amoA基因的实时 PCR 定量（× 10 ⁴ amoA基因拷贝 g ^-1土壤）在休耕时为 19.33，在对照中为 43.33，在 100% NPK 中为 30.33，在 100% NPK + FYM 中为 29.33。古生菌的amoA基因拷贝（x 10 ⁴基因拷贝g ^-1土壤）范围为11.67至38.67。土壤的X射线衍射(XRD)表明，NH ₄ ⁺矿物质的强度在对照中最高，在休耕中最低。大豆籽粒和生物量产量在 100% NPK + FYM 中最高，而在对照中最低。该研究强调，不施肥的连续种植可能会改变土壤微生物代谢，以便从容易获得的矿物部分的矿化中获取氮。