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Spatial variability of soil properties such as soil structure and soil penetrometer resistance (SPR) is relevant for identifying those zones with physical degradation. We used classical statistical and multifractal analyses for characterising the spatial patterns of SPR distributions and compared them at different soil depths to investigate the tillage effect in soil compaction. The study was conducted on an Ochrept dedicated to olive orchards for the last 70 years. Two parallel transects of 64 m were selected as different soil-management plots: conventional tillage and no tillage. Penetrometer resistance readings were carried out at 50-cm intervals within the first 20 cm of soil depth. Two-way analysis of variance (ANOVA) highlighted that tillage system, soil depth and their interaction were statistically significant to explain the variance of SPR data from 5 to 20 cm soil depth. The scaling properties of each SPR profile were characterised by [tau](q) function, calculated in the range of moment orders (q) between -5 and +5 taken at 0.5 lag increments. Several parameters were calculated from this: the singularities of strength (a); the Hausdorff dimension (f([alpha])); entropy dimension ([[alpha].sub.]); and their multifractal spectrum, i.e. graph [alpha] v. f([alpha]). Multifractal scaling was evident and added valuable information to describe the spatial arrangement of depth-dependent penetrometer datasets in all soil layers, which was complementary to the ANOVA results. Additional keywords: ANOVA, multifractal analysis, olive orchard, soil degradation., Introduction Much attention has been devoted to extensive soil degradation occurring in the Mediterranean Basin, particularly under permanent crops such as grapes and olives. Recent reports have highlighted the negative [...]

The adoption of no-till farming systems has greatly reduced energy and machinery inputs while significantly improving soil health and productivity. However, the control of crop weeds and diseases in no-till (NT) systems has become increasingly difficult for landholders in Australia's northern grains regions, with occasional strategic tillage (ST) being considered as a potential management option. This study investigated the effects of occasional ST on physical, chemical and biological soil properties, productivity, and weed control on five long-term (7-44 years) NT-managed soils. The study area extended from Biloela (Vertosol, 666 mm annual rainfall), Condamine (Sodosol, 624 mm annual rainfall), Moonie (Dermosol, 636 mm annual rainfall) and Warwick (Vertosol, 675 mm annual rainfall) in Queensland to Wee Waa (Vertosol, 582 mm annual rainfall) in New South Wales. Tillage treatments included chisel, offset disc and prickle-disc chain with various timings and frequencies. Soil samples (0-0.3 m) obtained 3 and 12 months after occasional ST were analysed for total and particulate organic carbon (TOC, POC), available phosphorus (P), bulk density, soil water, and microbial enzymatic activity. In-crop weed density was also recorded. One-time tillage, with chisel tines, offset disc or chain harrows, in long-term NT helped to control winter weeds in the first year, with variable results in the second year. Grain yield overall showed no significant impact in either year, except on the Brown Sodosol (P=0.08) in the first year. The initial impacts of strategic tillage on soil water were largely restricted to the 0-0.1 m depth range, with slight, non-significant decreases occurring. Available P, TOC, POC and total microbial enzymatic activity were not significantly impacted by either cultivation frequency or implement type. The use of an occasional ST for the purpose of weed control could be utilised as a viable management option for NT systems in the region without impacting on long-term productivity. Additional keywords: no tillage, productivity, strategic tillage, soil quality properties., Introduction Within agricultural systems, the aim of no-till (NT) or conservation farming is to enhance soil health so that the land can maintain or increase farm profitability, as well as [...]

The combination of the no-till planting system (NTS) and pasture (e.g. brachiaria grass, Urochloa sp.) for livestock production constitutes a crop-livestock integration (CLI) system. CLI systems significantly increase the total organic carbon (TOC) content of soil and the particulate organic carbon (POC) of soil organic matter (SOM). The present study evaluated TOC and the granulometric fractions of SOM under different management systems in a Cerrado area in the state of Goias. Two areas applying crop rotation were evaluated, one using CLI (corn/brachiaria grass/bean/cotton/soybean planted sequentially) and the other NTS (sunflower/pearl millet/soybean/corn planted sequentially). A third area covered with natural Cerrado vegetation (Cerradao) served as a reference to determine original soil conditions. Soil was randomly sampled at 0-5, 5-10, 10-20, and 20-40 cm. The TOC, POC, and mineral-associated organic carbon (MOC) were assessed, and POC and MOC stocks calculated. The CLI system resulted in greater TOC levels than NTS (0-5, 5-10, and 10-20 cm). Compared with the Cerradao, CLI areas exhibited higher stocks of TOC (at 5-10 and 10-20 cm) and POC (at 0-40 cm). Results obtained for TOC and POC fractions show that land management with CLI was more efficient in increasing SOM than NTS. Moreover, when compared with NTS, the CLI system provided better POC stratification. Additional keywords: carbon stocks, crop-livestock integration, no-tillage system, particulate carbon., Introduction The Cerrado is the second largest Brazilian biome, exhibiting complex dynamics that are strongly affected by seasonal fluctuation and anthropogenic activity (Bolliger et al. 2006; Sano et al. 2007). [...]

We analysed results of a long-term experiments, initiated in 1973 on a sandy loam soil under rainfed condition and in 1995-96 on a silty clay loam soil under irrigated condition, to determine the influence of using different combinations of mineral fertiliser (NPK) and fertiliser + farmyard manure (FYM) at 10 Mg/ha on soil organic carbon (SOC) content and its changes in the 0-0.45 m soil depth. Fertilisation always caused a net gain in SOC stock. Such gain was positively proportional to the amount of C incorporated into the soils. Concentration of SOC in the 0-0.45 m depth increased by 44% in NPK + FYM treated plots compared with NPK (44.4 Mg C/ha) after 32 years under rainfed condition and by 14% in the NPK + FYM treated plots compared with NPK (41.76 MgC/ha) after 9 years under irrigation. Mean (across treatments) total C added under the rainfed and irrigated systems was 2.67 and 3.03 Mg/ha.year, respectively. It was estimated that ~20 and 25% of the gross C input contributed towards the increase in SOC content under the rainfed and irrigated systems, respectively. Carbon loss from native soil organic matter (SOM) averaged ~61 and 261 kg C/ha.year under the rainfed and irrigated systems, respectively. Furthermore, mean stabilisation of added C in the plots under the rainfed condition (~16%) was higher than that (-13%) observed under the irrigated condition. Conversion of total added C to SOC was similar in the NPK and NPK + FYM treated plots under both growing conditions. In the NPK + FYM plots, ~38 and 29% of the C added through FYM was accounted for in the form of total SOC under the rainfed and irrigated conditions, respectively. The estimated quantity of biomass C required to maintain equilibrium SOM content under the rainfed and irrigated systems was 0.29 and 1.08 Mg/ha.year. The total annual C input by the soybean-wheat rotation in the unfertilised control plots under rainfed condition was 0.87 Mg/ha.year and with N fertiliser only under the irrigated condition was 1.75 Mg/ha.year. Thus, SOC augmentation under long-term soybean-wheat cropping was due to higher annual C input than the required amount to maintain equilibrium SOM content. Although FYM addition along with NPK improved total SOC stock and carbon sequestration potential, it did not encourage the stabilisation rate of added C. Hence, C stabilisation that takes into account the total C added in the system is a better indicator of assessing SOC sequestration, in summary, mineral fertilisation improved C sequestration capacity of soybean-wheat system in the Indian Himalayas and manure addition along with mineral fertilisers further improved it. Additional keywords: Carbon addition and storage, farmyard manure, sub-temperate Indian Himalayas, soybean-wheat cropping, rainfed and irrigated conditions., Introduction Attempts are needed to enrich global soil organic carbon (SOC) stocks through sequestration of atmospheric C to curb global warming. Optimum levels of SOC can be managed through adoption [...]