Improvement of the soil fertility of a volcanic indurate layer (Tepetate) by applying acid treated biosolids
Volcanic indurate matter produces low soil fertility when rises to the surface, reducing the agricultural potential of the land and distressing marginal zones that live from agriculture. The habilitation of these materials using biosolids has not been explored, although the problem exists in several countries around the world. This work evaluated the impact of the application of biosolids on the fertility of a fragmented volcanic indurate layer (Tepetate). Tepetate’s fertility was measured before and after biosolids application with three biosolids application rates: agronomic rate (AR), as well as 10 and 20xAR. Biosolids were mixed with Tepetate and kept in pots under green house conditions along with a control, during four months. One set of pots with and without vegetative species. Organic matter content increased between 180 and 470% compared to the control. Cation exchange capacity (21.8 to 42.3 Cmol+kg-) resulted adequate for keeping nutrients for plants. pH values were adequate for agricultural activities (5.9-7.2). Dry color of the Tepetate, becomes darker (grayish brown; 10YR 5/2) than the initial yellowish brown (10YR 5/4) because of the addition of stable organic matter from biosolids. Considering edaphologic characteristics it is suitable to habilitate volcanic indurate layer by the application of biosolids.
Subsurface injection versus surface application of composted municipal solid waste in cotton production.
Equipment was developed and tested for injection and broadcast application of municipal solid waste (MSW) compost at selected rates to agricultural land for cotton production. Replicated tests were conducted to determine the effects of injected vs. broadcast applied compost on soil parameters (organic matter, soil compaction, and soil fertility) and plant growth. All broadcast application rates of compost significantly reduced hardpan formation in the top 6in. of soil compared to no compost application. In addition, all rates of injected material significantly reduced soil compaction in the Eand B-horizons (6-18 in.). Injected applications did not affect compaction in the top 6-in. of soil. Broadcast application of compost significantly increased soil organic matter content 6and 12-weeks-after planting proportional to the compost application rate. In addition, soil nitrogen content was significantly higher in the broadcast application plots 6-weeks-after planting. Twelve-weeks-after planting, only application of 12tons/acre compost (broadcast) statistically increased soil nitrogen content averaged over the top 8 in. of the soil. MSW compost (broadcast or injected) significantly increased plant N, P, and K contents compared to no compost application. Increases in plant nitrogen were proportional to application rates. In addition, injected application increased plant sulfur compared to no compost application. All rates of compost (injected or broadcast applications) significantly increased cotton lint yield compared to no compost application. Yield increase was proportional to application rates. For the 12 tons/acre injected application treatment, yield increases were 23%, 24%, and 44% in 1997, 98 and 99, respectively compared to no compost application. Compost significantly increased plant height. Height increase was proportional to application rate. Vitazyme increased plant N, P, and K contents with no effects on Ca, Mg, and S. Vitazyme increased cotton lint yield 31 lb/acre or 3%. In addition, soil nitrogen content 6-weeks-after planting in plots treated with Vitazyme was 12% higher than no-Vitazyme plots.
Shapes of aggregates from tilled layers of some Dutch and Australian soils
Abstract Five different methods were used to study the shapes of soil aggregates oriented in their planes of maximum projection. A measure of roundness was found to be relatively insensitive to shape features. The shortest aspect ratio (the ratio of the shortest to the longest diameters through the centroid) was found to be most sensitive of the “single value” shape measures. More comprehensive shape information was given by values of the radius spectra and the curvature spectra. The curvature spectra method seems to be slightly more sensitive than the radius spectra method and can also be applied to reentrant particles. Generally it was found that aggregates are less round with increasing clay content and decreasing organic matter content. There was also a hint that aggregates of the Dutch soils may become less round with increasing age since their reclamation. The Australian soil aggregates were slightly rounder than the Dutch aggregates.