Organic matter and soil conservation

Even before the end of the eighteenth century much of the areas on the East Coast that had at one time been cropped were now abandoned to forests. Lands farther west that were far more fertile took the place of the abandoned eastern acres. But the settlers soon found that even many of these fertile areas did not long continue to produce as they did initially. This was due in part to removal of nutrients, but also to a great extent to 

The destructive effects of soil erosion are much in evidence, but the exact mechanisms by which the soil is carried away are much less understood. Heavy rains, running water, and high wind velocities are obviously the causative agents, but when this is stated we have only touched on the more obvious factors or forces. We need to go a little deeper into the phenomena in order to understand better how these destructive forces can be counteracted. 

Wind erosion is most obvious, and often most serious, in semiarid or arid regions, where vegetative cover is scarce or absent, but winds can also do much damage in humid regions. Wet soils are not subject to wind transport, but even in humid regions the surface soil can become air-dry in a very short time. The more the soil surface is disturbed by cultivation in the absence of crops, usually the greater is the opportunity for wind to transport it. 

The removal of soil by water is due to the energy of the falling raindrop, and to the nearly horizontal movement of the water that flows over the soil surface. Both processes or forces act simultaneously. Under conditions that favor erosion, the amount of soil removed increases as the slope increases. A soil of zero slope would obviously not be eroded, although the impact of raindrops would damage the surface of exposed soil by puddling and sealing it against the entrance of water and air. 

Losses of soil as a result of water erosion have been shown to be closely correlated with the number and intensity of thunderstorms. This is illustrated by the data from Piedmont soils reported by Barnett et al. (1960), and shown here as Fig. 27.1. They state that during the previous 20 years an average of 11 thunderstorms per year caused 86% of the erosion and accounted for 56% of the rainfall. These storms, lasting an average of about 2.5 h, occur chiefly during the hottest months of the year when evapotranspiration is highest and when little of the rainfall penetrates into the subsoil (see Fig. 13.2 and 13.3). 

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An increase in the supply of fertilizer N can, in turn, result in an increase or decrease in below-ground C production, depending on the experimental conditions and plant species used. At high N rates, the decomposition of native. soil organic matter seemed lowered (conserving effect), as reflected by the decrease in the rate of respiration of unlabeled soil-C, both in crop (90) and forest soils (108,109). 

Biomass development (Jordan 1985) and regeneration capacity (Uhl 1987) are not always clearly associated with differences in soil fertility, but they are certainly related to rates and patterns of nutrient cycling (Vitousek and Sanford 1986, Medina and Cuevas 1989, Tiessen et al. 1994b). On poor soils, nutrients may cycle without substantial losses from the system (Baillie 1989, Burnham 1989). In such dystrophic systems, organic matter and particularly the forest litter mat may play an essential role in conserving nutrients for sustaining forest produaion (Stark and Jordan 1978). 

Utilization of By-product. Oil Palm Trunks and Fronds. Under normal plantation practices, the pruned fronds are placed along the palm interrows and act as mulch. Besides conserving soil moisture and reducing soil surface erosion, the fronds on decomposition return organic matter and slowly release plant nutrients to the soil (Table 27). 

Refill the hole with the soil you had removed, and water the plant well to give the plant a good start. Stake or trellis as needed to prevent damage, and reduce disease by encour-aging good air circulation around the branches and between plants. Mulch to keep weeds under control, supply a slow release of organic matter, and conserve soil moisture. 

The authors point out that organic, or bog, soils present many land-use problems such as those connected with market gardening, farming, wildlife preservation, water conservation, control of floods and erosion, and use as sources of organic matter for soil improvement. The character of the surface material, profile, mineral substratum, and ground-water conditions determine the suitability of the soils for special crops such as onions and celery, or for grain and livestock farming. 

Soils. Granite Reef soil is a sandy loam soil, supplied by the U.S. Water Conservation Laboratory, USDA, Phoenix, AZ. Walla Walla soil is a soil which contains 30% clay and organic matter, supplied by the Columbia Plateau Conservation Research Center, USDA, Pendleton, OR. 

Tables 12.2 and 12.3. The effect of vertical variability is shown in Table 12.2, while the lateral spatial variability is shown in Table 12.3. The vertical and lateral spatial variabilities were defined on the basis of either the measured adsorption coefficient K), as generated from adsorption isotherms on soil profiles, or on adsorption coefficients on soil organic matter calculated as adsorption on organic carbon per unit weight of soil. We see that both vertical (Table 12.2) and lateral (Table 12.3) variability of soil affect the adsorption coefficients. A comparison between the bromide (conservative) and the two nonconservative herbicides distributions with depth after about 900mm of leaching is shown in Fig. 12.3. We see that, in the case of bromide, there is a continuous displacement of the center of mass with cumulative infiltration. In contrast, the bulk of the herbicide contaminant mass remains in the upper soil layer, with very little displacement.

Nortcliff, S. (2005). Soil organic matter—The potential benefits and necessary precautions required in the use of composts and biosolids as soil amendments in agricultural ecosystems. In Application of the Emerging Soil Researches to the Conservation of Agricultural Ecosystems, Yang, I. E., Sa, T. M., and Kim, I. I., eds., KSSSF, KSAE, RDA, Korea, pp. 81-93. 

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