The effectiveness of conservation agriculture (CA) and other soil management strategies implying a reduction of tillage has been shown to be site-dependent (crop, clime and soil), and thus any new soil and crop management should be rigorously evaluated before its implementation. Moreover, farmers are normally reluctant to abandon conventional practices if this means putting their production at risk. This study evaluates an innovative soil and crop management (including no-tillage, cover crops and organic amendments) as an alternative to conventional management for rainfed cereal cropping in a calcareous soil in a semi-arid Mediterranean climatic zone of Navarra (Spain), based on the analysis of soil water retention curves (SWRCs) and soil structure. The study was carried out in a small agricultural area in the municipality of Garínoain (Navarre, Spain) devoted to rainfed cereal cropping. No other agricultural area in the whole region of Navarre exists where soil and crop management as proposed herein is practiced. Climate is temperate Mediterranean, and the dominant soil is Fluventic Haploxerept. Within the study area there is a subarea devoted to the proposed soil and crop management (OPM treatment), while there is another subarea where the soil and crop management is conventional in the zone (CM treatment). OPM includes no-tillage (18 years continuous) after conventional tillage, crop rotation, use of cover crops and occasional application of organic amendments. CM involves continuous conventional tillage (chisel plow), mineral fertilization, no cover crops and a lower diversity of crops in the rotation. Undisturbed soil samples from the topsoil and disturbed samples from the tilled layer were collected for both systems. The undisturbed samples were used to obtain the detailed SWRCs in the low suction range using a HYPROP©device. From the SWRCs, different approaches found in the literature to evaluate soil physical quality were calculated. The pore-size distribution was also estimated from the SWRCs. Disturbed samples were used in the laboratory to assess soil structure by means of an aggregate-size fractionation and to perform complementary analysis from which other indicators related to soil functioning and agricultural sustainability were obtained. The approaches evaluated did not show clear differences between treatments. However, the differences in soil quality between the two forms of management were better observed in the pore size distributions and by the analysis of the size distribution and stability of soil aggregates. There was an overabundance of macropores under CM, while the amount of mesopores (available water) and micropores were similar in both treatments. Likewise, more stable macroaggregates were observed in OPM than in CM, as well as more organic C storage, greater microbial activity, and biomass. The proposed management system is providing good results regarding soil physical quality and contributing also to the enhancement of biodiversity, as well as to the improvement in water-use efficiency. Finally, our findings suggest that the adoption of the proposed practice would not result in a loss in yields compared to conventional management.

中文翻译：

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基于详细保水曲线的创新长期土壤和作物管理对地中海土壤表土特性的影响

保护性农业 (CA) 和其他意味着减少耕作的土壤管理策略的有效性已被证明取决于场地（作物、气候和土壤），因此任何新的土壤和作物管理在实施之前都应进行严格评估。此外，如果这意味着他们的生产面临风险，农民通常不愿意放弃传统做法。本研究评估了一种创新的土壤和作物管理（包括免耕、覆盖作物和有机改良剂），以替代纳瓦拉（西班牙）地中海半干旱气候区钙质土壤中雨养谷物种植的常规管理，基于关于土壤保水曲线（SWRCs）和土壤结构的分析。该研究是在加里诺安市（纳瓦拉，西班牙）致力于雨养谷物种植。在整个纳瓦拉地区，没有其他农业区实施本文提出的土壤和作物管理。气候是温带地中海，主要土壤是 Fluventic Haploxerept。在研究区域内，有一个分区专门用于拟议的土壤和作物管理（OPM 处理），而另一个分区是该区域的常规土壤和作物管理（CM 处理）。OPM 包括常规耕作后的免耕（连续 18 年）、轮作、使用覆盖作物和偶尔使用有机改良剂。CM 涉及连续常规耕作（凿犁）、矿物施肥、无覆盖作物和轮作中作物多样性较低。两个系统都收集了来自表土的未扰动土壤样品和来自耕作层的扰动样品。未受干扰的样品用于使用 HYPROP© 装置在低吸力范围内获得详细的 SWRC。根据 SWRC，计算了文献中评估土壤物理质量的不同方法。还从 SWRC 估计孔径分布。实验室使用扰动样品通过骨料大小分级评估土壤结构，并进行补充分析，从中获得与土壤功能和农业可持续性相关的其他指标。评估的方法没有显示出治疗之间的明显差异。然而，两种管理方式的土壤质量差异在孔径分布和土壤团聚体的粒度分布和稳定性分析中得到了较好的观察。CM 下大孔过多，而中孔（有效水）和微孔的数量在两种处理中相似。同样，在 OPM 中观察到比在 CM 中更稳定的大聚集体，以及更多的有机碳储存、更大的微生物活性和生物量。拟议的管理系统在土壤物理质量方面提供了良好的结果，也有助于增强生物多样性，以及提高用水效率。最后，我们的研究结果表明，与传统管理相比，采用建议的做法不会导致产量损失。