Soil acidity and poor nutrient use efficiency are major limiting factors as regards output potential on heavy soils, soils which are dominated by high proportions of clay and organic matter, with impeded drainage, high buffering capacity and located in high rainfall areas. Lime is applied in order to counteract these limiting factors and in turn improve agricultural output and productivity. The current study investigates the effects of two commonly used lime products at three comparable treatment rates, ground lime (7.5, 5 and 2.5 tonne/ha) and granulated lime (7.5, 2.5 and 1.5 tonne/ha), applied across three distinct sites. The ability of each lime product and treatment rate to counteract soil acidity, increase nutrient availability and influence soil physical structure was assessed over time. On average across sites, 1 tonne/ha of each lime product increased soil pH by 0.15 and 0.21 pH units between ground and granulated lime, respectively. Site 3 experienced the greatest increase change in soil pH in comparison to the other two sites, largely due to lower clay content and cation exchange capacity. Granulated lime was 5.7 times more expensive than ground lime in its ability to reduce soil acidity. The high treatment rate showed the greatest reduction in soil acidity, aluminium and iron concentration as a mean across all sites. Morgan's soil test phosphorus concentration increased across all sites, with treatment rates having no effect on the rate of increase. There was evidence of reduced soil compaction and lime application showed no negative implication on soil physical structure.

The depth distribution of weed seed, their location in relation to soil aggregates, and the size distribution of soil aggregates were determined in fields that had been under continual conventional or reduced tillage for more than 12 years. Soil samples were taken at three depths in the spring and fall of 1982, and soil aggregates were classified into seven size classes by dry, rotary sieving. Subsamples were deflocculated and washed through sieves to recover weed seed. In the spring, 85% of all seed in the reduced-tillage and 28% of those in the conventional-tillage soil were in the 0- to 5-cm-depth layer. Conventional tillage incorporated weed seed uniformly into various soil aggregate classes, whereas with reduced tillage more seed accumulated in the unaggregated fraction of the soil. In the fall, weed seed distribution in relation to soil depth and among soil aggregate classes was similar for both tillage regimes.

Growth chamber and laboratory experiments evaluated the effects of seed-soil microsite characteristics on seed germination. When corn (Zea mays L. ‘Pioneer 3541’), soybean [Glycine max (L.) Merr. ‘Corsoy 79’], velvetleaf (Abutilon theophrasti Medic. ♯ ABUTH), and giant foxtail (Setaria faberi Herrm. ♯ SETFA) were seeded among soil aggregates 2.50 to 1.25 cm in diameter in the growth chamber, there was decreased seedling emergence with decreasing frequency of irrigation. These same species seeded inside artificial soil aggregates showed increased seedling emergence with decreasing frequency of irrigation. The germination of corn and soybean seed inside 0.4-g, fully moist soil aggregates incubated in the laboratory under high relative humidity conditions was significantly decreased relative to seed incubated in the absence of soil. Velvetleaf and giant foxtail germination was significantly reduced by 0.1-g soil aggregates. Rice (Oryza sativa L.) had 68% emergence from 1.0-g, fully moist soil aggregates, whereas larger seeded corn and soybean had only 20 and 10% emergence, respectively. Germination inhibition of giant foxtail seed by fully moist soil was partially reversed by incubating seed-containing aggregates in an atmosphere of 75% oxygen.

The effects of irrigation and the rainy season on soil gases, water and physical properties were studied in a lowland moist forest in Panama. Two control plots experienced a normal four-month dry season and two experimental plots were irrigated during the dry season.

The forest soils were well aerated. The average soil oxygen content at 20 cm never dropped below 15%. Irrigation in the dry season resulted in treatment effects on soil oxygen and water that persisted throughout the rainy season. The late rainy season soil oxygen content at 20 cm was 18.2% in the control plots and 16.8% in the irrigated plots. The late rainy season soil water content at 0–10 cm was 0.34 m3 m-3 in the control plots and 0.36–0.37 m3 m-3 in the irrigated plots. In the control plots, in the absence of any experimental manipulation, the soil physical properties changed within a single rainy season. Specifically, soil oxygen dropped and soil water increased during the eight-month rainy season.

The observed alterations in soil physical properties probably resulted from changes in soil structure and the abundance of large pores. The rainy season or irrigation may decrease soil porosity by dispersing aggregates of soil particles, whereas soil desiccation during the dry season may enhance the formation of aggregates and large pores. As a result, the irrigated soils held more water and were less permeable to gas and water than soils experiencing a normal dry season. We conclude that the dry season may play an important role in maintaining soil structure.

Field experiments were conducted to investigate the mechanism underlying patterns of the rove beetle populations in apple and pear orchards (1998–2002) and winter wheat (2006–2007) in Hungary following treatment with broad-spectrum insecticide. The capacity of predatory staphylinid species to feed on cereal pests was measured, with six species tested in petri dishes, in the laboratory at room temperature. Almost 23% of the Hungarian and 13% of the European staphylinid fauna are represented in the investigated agro-ecosystems. In orchards, 5236 individuals, belonging to 253 species, were collected. The most widely occurring were Omalium caesum Gravenhorst, Drusilla canaliculata (F.), Dinaraea angustula (Gyllenhal), Palporus nitidulus (F.), Xantholinus. longiventris (Olivier), X. linearis (Olivier) and Aleochara bipustulata (L.). In winter wheat, 798 individuals and 20 species were collected, the most frequent were Staphylinus caesareus Cederh, Tachyporus hypnorum (F.), Philonthus cognatus (Stephens), Aloconota gregaria (Erichson), Tachyporus chrysomelinus (L.) and T. obtusus (L.). Species composition differed by crop (apple, pear and wheat), soil composition and surrounding habitat. Species diversity was also influenced by these parameters. In wheat, one acute change in species composition was observed with the decline of Tachyporus spp., which occurred equally across all farms. The consumption rate of prey by the dominant species occurring in wheat ecosystems was relatively high; however, we did not offer any fungal food to compare with insects' prey.

A critical step in the quantification of soil quality (SQ) is the selection of SQ benchmarks. The benchmarks used in this study were SQ ratings made by 32 farmer collaborators representing a range of farming systems, scales of operation and geographic locations in the Mid-Atlantic region of USA. Soils from 45 pairs of sites identified by their farmers as having good and poor SQ were sampled over three seasons and analyzed for 19 soil parameters. Farmer judgments of SQ were based on many factors, most commonly soil organic matter, crop performance, soil water availability and erosion history. Selected individual soil parameters were normalized and integrated into an additive SQ index (SQI). Three additional indices were developed using discriminant analysis. The level of agreement between individual parameters, SQIs and farmer SQ ratings was evaluated using paired t-tests and mean percent difference values. The additive SQI was found to have the highest level of agreement with farmer SQ ratings (P<0.0001), demonstrating that a linear combination of soil parameters can be assembled that is more in agreement with holistic SQ criteria, such as farmer SQ ratings, than individual soil parameters. Extractable C from microwave (MW) sterilized soil (a measure of microbial biomass) was the individual parameter that best agreed with farmer SQ ratings (P<0.0001). Five additional soil C parameters, as well as aggregate stability, also agreed well with farmer SQ ratings (all P values <0.0005). The three parameters with the highest ratio of mean percent difference to coefficient of variation (an indication of parameter reliability) were extractable C from MW sterilized soil, anthrone reactive C and macroaggregate stability (14.2, 7.7 and 3.7, respectively). Mineral fertility parameters (pH, Ca, Ca:Mg ratio, P and K) were not significantly related to farmer SQ ratings (P values >0.05). The strong relationships observed between soil C parameters, soil structural parameters and farmer SQ ratings suggest that efforts to improve SQ in the study region should focus on monitoring and enhancement of soil C and soil structure.

The spatial organisation of soils is crucially important in affecting belowground function, and the associated delivery of ecosystem services. Fungi constitute an important part of the soil biomass. As well as playing key roles in nutrient cycling and biotic interactions, they are also intimately involved in soil structural dynamics. Fungi mediate the formation of soil structure at a variety of spatial scales via charge, adhesive and enmeshment mechanisms. They also produce large quantities of hydrophobic compounds that affect water infiltration properties of soils. Fungi can also destroy soil structure via decomposition of organic matter that affects soil aggregation. In turn, soil structure affects fungi. The filamentous growth-form of fungi is a very efficient spacefilling structure well adapted for life in a spatially heterogeneous environment such as soil, but the labyrinthine pore network ultimately regulates how fungal mycelia grow through and function within the soil. The distribution of water within soils plays a crucial role in governing fungal development and activity, as does the spatial distribution of nutrient resources. This article reviews the continual interplay that occurs between soil structure and fungi, and discusses how self-organisation mechanisms may operate in the soil system.

Wood residues are applied to soils to improve their organic matter content and related biological, physical, and chemical properties. We monitored the changes in soil total C and N content, the bacterial, fungal and actinomycetal populations, and microbial biomass and activity during 20 weeks in the first season following the application of chipped wood from twigs (CWT), and as residual effects during the second growing season on a loamy soil (coarse loamy, mixed, frigid, Humic Fragiorthod) in Sainte-Brigitte-des-Saults (Québec) Canada. Wet-aggregate stability and the content of nutrients of the soil also were determined. Adding CWT stimulated the bacterial and actinomycetal populations very rapidly (within 8 weeks); in the second season the effect was less pronounced and gradually disappeared. The most significant and long-lasting effect was on the fungal population in two consecutive years of observation, with increases of up to 24-fold. This stimulation of fungi possibly was responsible for the large and significant increase in wet-aggregate stability observed in the second year. The effect of CWT on alkaline phosphatase activity and total C and N was observed only in the second season. Some immobilization was seen only in the season immediately following residue application. The addition of the CWT also supplied micronutrients, in particular Zn, which would make it a useful source of some elements in deficient soils. Application of CWT to this soil greatly improved its quality, as revealed by its biological, chemical, and physical attributes.

A review of orchard soil management effects on tree growth and soil parameters is presented. It shows the gap between present common practices and results achievable in other systems. An alternative soil management system for newly planted peach trees, termed “killed-sod”, is described. This system has improved soil structure and rainfall infiltration and greatly increased early tree growth and yield. A fertilization study has demonstrated that the addition of a complete fertilizer in four different soil management systems could not account for the increased growth resulting from the improved soil environment in the killed-sod system.