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Dynamic soil properties as affected by machine-soil interaction are potential indicators for the evaluation of management and traffic effects on soil structure. Our objective was to determine compressive, shear, and hydraulic soil properties in a sandy clay loam Hapludalf, under continuous no-tillage and tillage operations to ameliorate soil physical conditions. The studied tillage systems were long-term (13 years) continuous no-tillage (NT c ); chisel tillage two years before the experiment (CH 2 ); inverting tillage performed on NT soil, 2 years before and just-before the experiment (IT 2,0 ); and chisel tillage performed on NT soil 3 years before and just-before the experiment (CH 3,0 ). Soil precompression stress, compressibility coefficient, cohesion, angle of internal friction, aggregate resistance, bulk density, porosity (total, macroporosity, microporosity), and water retention (field capacity, permanent wilting point, available water, and drainable water) were determined for 0.01–0.03 m (surface) and 0.10–0.12 m (subsurface) soil layers. The results show inverting and chisel tillage of soil previously under long-term no-tillage has little and/or short-lasting effect on soil composition and functional physical properties. Soil reconsolidation over time significantly affects soil structural condition. Thus, soil tillage is not need to improve soil structure of sandy clay loam subtropical soil. Furthermore, the terms capacity and intensity properties should not be used as synonyms to composition and functional properties, but they should rather be reserved to the thermodynamically basic quantity-intensity-capacity concept. [ABSTRACT FROM AUTHOR]

Soil surface is the locus of complex apportioning of mass and energy reaching the Earth. Pore system functioning of the surface soil, particularly airflow within the soil matrix, is affected by soil deformation. Our objective was to evaluate the effect of soil structure, moisture, and granulometry on soil aeration properties of three Oxisols and one Ultisol managed under no-tillage. Undisturbed samples (572), collected from loose (0.00–0.075 m) and compact (0.075–0.15 m) soil layers, were capillary saturated for 24 h and equilibrated to nine water tensions, from 1 to 500 kPa, to determine capacity (bulk density, volumetric moisture, air-filled porosity, and degree-of-compactness) and intensity (air conductivity and permeability, blocked porosity, and pore continuity) soil physical properties related to aeration; whereas disturbed soil samples were used for soil granulometry analysis. Soil granulometry, moisture, and structure (soil compaction) affect aeration capacity and intensity properties. Regardless of soil wetness, soil compaction reduces air-filled porosity, pore continuity, and air permeability. As soil moisture decreases, air permeability increases because of greater amount and continuity of soil pores available for air flow, and this increase in permeability is greatest in sandy-textured soil compared with clay-textured soils. Intensity properties are better descriptors of the time-variable aeration status of long-term no-tilled soils. [ABSTRACT FROM AUTHOR]

• Rice monocropping underutilizes the production potential of lowland soils. • Rotation with dryland crops improves soil conditions and increases farmers profit. • Tillage systems improve drainage for alternative crops in lowland soils. • Excessive rainfall lessens the benefits of tillage and ridging in lowland soils. • Profitable farming is possible by growing flood-tolerant crops in lowland soils. Lowland areas consist mostly of hydromorphic, poorly-drained soils, constituting an important agricultural frontier in Brazil and around the world. Flood-irrigated rice cultivation has become a monoculture in lowland soils, degrading soil structure and causing weed resistance, partially overcome by crop rotation and soil tillage. Rotation with dryland crops, such as soybean and corn, is an alternative that contributes to improving soil conditions and increase farmers' profit. For rice cultivation, the occurrence of a compacted layer with reduced porosity and hydraulic conductivity is beneficial since compaction reduces water loss by drainage during the flood-irrigated crop cycle. However, for dryland crops, this compacted layer prevents water infiltration, reduces soil volume explored by roots, and maintains flooding conditions for longer time. Chisel tillage disrupts the compacted layer, while the construction of ridges raises the root system out of the saturated layer, creating a favorable microenvironment for root growth. This review paper presents advances in cropping and soil tillage practices in poor drainage soils, offering different combinations to reduce costs and increase the efficiency of the production system. Profitable farming is possible by growing flood-tolerant crops with proper management practices, making lowland soils as an alternative to increasing food diversity and supply. [ABSTRACT FROM AUTHOR]

Tobacco is produced in Brazil mainly by small farmholders, on shallow soils on steeplands or on sandy soils, usually under intense soil tillage and lacking soil conservation measures, which can result in large losses of water, soil and nutrients such as P and K. We studied soil management systems for tobacco cropped using animal traction, on shallow soil on steeplands. On a Leptosol, we evaluated conventional tillage (CT), minimum tillage after fallow (MTf), minimum tillage after oat (MTo), no-tillage without ridge (NT), no-tillage with ridge (NTr) and no-tillage with consolidated ridge (NTrc), in a completely randomized blocks design with three replicates. Runoff plots of 1.2 m2 were used to determine water and soil loss by runoff, and total and soluble P and K losses in eight rainfall events during the tobacco crop cycle. Oat cultivation prior to tobacco provided higher dry-mass mulch production and the lowest proportion of exposed soil and rocks in NTr, NTrc and NT systems. The losses of water and of P and K in the soluble forms during the storm rainfall events evaluated were lower for NT management compared to the other treatments. Total soil loss for the monitored rainfall-events was 15 and 16 Mg ha−1 for CT and MTf management, and it was reduced about five times for MTo, NTrc and NTr treatments. However, the lowest soil loss was observed for NT (0.2 Mg ha−1). This same trend was observed for total losses of P and K, where NT reduced about 97 and 57 times the losses of these nutrients compared to CT. Therefore, these results show that conservation managements such as no-tillage or minimum tillage associated with winter cover crops without grounding of tobacco seedlings may be effective to reduce soil losses along with P and K adsorbed in the soil. However, reduction of losses of water, soluble and total P and K was only effective combining no-tillage with no ridge construction and winter cover crop. • Tobacco is produced in Brazil on shallow soils on steeplands by small farmholders. • Soil conservation measures reduced soil and water losses. • Soil losses for NT and CT were 0.2 and 16.0 Mg ha−1, respectively. • NT reduced about 97 and 57 times the losses of total P and K compared to CT. • NT combined winter with cover crops reduced water and soluble P and K losses. [ABSTRACT FROM AUTHOR]

• Tillage impacts initial growth of eucalyptus after eucalyptus in poor-soil steeplands. • Conventional downslope was compared to cross-slope tillage of varying intensity. • Intense cross-slope subsoiling after stump cutting plus ridging caused best growth. • Conventional downslope subsoiling was most economic. • Hole-drilling promoted lowest tree growth due to restricted root growth. The re-establishment of trees after previous forest harvesting (so-called second rotation) requires soil structure amelioration, since the tree harvest with heavy machinery usually causes soil compaction and deformation, mostly at the surface, but also in deeper layers. Efficient soil tillage methods are necessary to create a physical environment suitable for the next generation of trees to grow and develop successfully. The aim of this study was to evaluate the effect of four different soil tillage methods on soil physical properties and the initial growth of eucalyptus (Eucalyptus saligna) after eucalyptus on a gravelly Ultisol in southern Brazil with a compacted layer in 0.3 m depth. Tree seedlings were planted in randomized blocks in three replications after applying the following soil tillage methods: intermittent (every 4 m) downslope subsoiling (DSS), cross-slope subsoiling after above-ground stump cutting (C + CSS), cross-slope subsoiling plus ridging after above-ground stump cutting (C + CSS + R), and hole drilling (HD). Before as well as 122 and 391 days after planting, undisturbed and disturbed soil samples were collected in each tillage treatment in five layers down to 1.00 m to evaluate soil bulk density, macroporosity, microporosity, plant-available water content, and penetration resistance, along with chemical analyses. Operational costs and, where applicable, product costs of each method were compared, while the initial growth of E. saligna was evaluated by means of tree survival rate and height, diameter at breast height and wood volume 90, 180 and 330 days after planting. The tillage method did not affect soil chemical properties, but positively influenced physical properties by means of lower bulk density and penetration resistance. The most intensive and expensive method C + CSS + R provided the best conditions for tree growth, while HD was the cheapest method, but the least efficient due to low productivity. Per volume of produced wood, DSS was the most efficient method with lowest total costs and the second highest wood production. [ABSTRACT FROM AUTHOR]