Abstract Conservation agriculture (CA) is a farming system that promotes minimum soil disturbance, maintenance of a permanent soil cover, and diversification of plant species and was introduced also in the Veneto region of north east Italy. CA is not always viewed as a win-win solution for sustainable production because of the increase in soil strength and compaction that may negatively impact root growth and crop production. In this study, our aim was to analyse root length density (RLD), mean diameter (MD), and root distribution to 90 cm at the flowering stage, following a maize-soybean-winter wheat rotation cycle under CA and conventional tillage (CV) at four farms. Root traits were related to soil physical properties (gravimetric water content, bulk density, and electrical resistivity) and to existent critical limits of penetration resistance (PR), and the degree of compactness (DC). CA management was not detrimental to root development and positively affected the RLD of maize (+70 %), soybean (+121 %) and winter wheat (+20 %) at 0–10 cm most likely because of increased nutrient availability. No specific physical limitations of soil were highlighted for the crop root apparatus in three (silty soils) out of four farms. Farm 3 (sandy soil) with a hardpan below 35 cm caused lateral root development in winter wheat, but not in maize or soybean. The yield gap between CA and CV (-3.9 t ha−1 for maize, -0.4 t ha-1 for soybean and -0.7 t ha-1 for winter wheat) may have been due to other agronomic factors, notably insufficient weed control in CA. Critical limits of PR (2 or 33.5 MPa) and DC (87 %) did not seemed to impair root traits, irrespective of the tillage system, suggesting that further studies on soil-specific mechanisms between soil compaction and root apparatus are warranted.

中文翻译：

---

保护性农业管理下玉米-大豆-冬小麦轮作作物根系性状研究

摘要 保护性农业 (CA) 是一种促进最小土壤扰动、保持永久土壤覆盖和植物物种多样化的农业系统，也被引入意大利东北部的威尼托地区。CA 并不总是被视为可持续生产的双赢解决方案，因为土壤强度和压实的增加可能会对根系生长和作物生产产生负面影响。在这项研究中，我们的目的是分析根长密度 (RLD)、平均直径 (MD) 和在开花期根分布到 90 厘米，遵循 CA 和常规耕作 (CV) 下的玉米 - 大豆 - 冬小麦轮作周期) 在四个农场。根系性状与土壤物理性质（重量含水量、容重、和电阻率）以及现有的渗透阻力 (PR) 和致密程度 (DC) 的临界极限。CA 管理对根系发育无害，对玉米 (+70%)、大豆 (+121%) 和冬小麦 (+20%) 在 0-10 cm 处的 RLD 产生积极影响，这很可能是因为养分可用性增加。四个农场中的三个（粉质土壤）的作物根系没有强调土壤的特定物理限制。具有低于 35 cm 的硬土的农场 3（沙土）导致冬小麦侧根发育，但在玉米或大豆中没有。CA 和 CV 之间的产量差距（玉米为 -3.9 t ha-1，大豆为 -0.4 t ha-1，冬小麦为 -0.7 t ha-1）可能是由于其他农艺因素，特别是杂草控制不足CA。PR 的关键限值（2 或 33。