Nutrient Conservation and Cycling

The loss of nutrients during harvesting can be compensated for by investing in nutrient recycling, soil fertility, and decreasing erosion, nutrient leaching, run-off, and burning.

Mandal (2022) devoted a full chapter to discussing soil and water conservation and erosion. A summary is nevertheless beneficial sometimes. The topsoil is where nutrients are concentrated, especially those that are stationary and are not washed (leached) down. Where may it be found:

The soil has been washed away from roots and the sides of stones, and can be seen to have been sifted and deposited by water or wind into fine and coarse fractions.

Increased surface protection against live, dead, or other objects might lessen erosion risk or intensity throughout the season. Moreover, they can support and maintain the biological activity and organic matter in the soil. Large trees can reduce or prevent wind erosion, but if the area close to the soil's surface is naked and open, the erosive wind or larger, connected water drops will have more speed and erosive energy per square meter. Similar to how slowing water or wind is preferable to outright obstruction since the flow can bypass with concentrated power and faster speed. Also, once erosion begins, it just leads to more erosion, therefore it is preferable to stop it before smaller sand particles knock more of them loose or water flows more quickly by creating deeper gullies or rills. It's crucial to have more appropriate plant cover along the slope's direction, even when the fields are barren. This may need for more effective, affordable establishing techniques, multifunctional plants, early advantages like water conservation, and little crop rivalry. In his Wikifarmer Library pages on nitrogen and legumes and on soil and water conservation with agroforestry, Mandal (2022) mentions some creative methods with citations. Co-benefits may also include less direct damage from strong and drying winds or water flow, fodder, fuel, fruits, green manure, weed reduction, and saved weeding efforts. Other advantages include providing home for natural enemies of pests that attack seasonal crops, allowing plants to capture leached nutrients, etc.

Widespread recycling of nutrients

The amount of total or biologically available that can be recycled must be increased to make up for its significance, even though it might not be sufficient. Recycling may not be ideal, for instance, if harvests are sold or if there are losses that cannot entirely be prevented. Certain nutrients could be present in larger or lower concentrations than necessary. The article on nitrogen discusses biological nitrogen fixation, which is not recycling for the local environment but the global environment. In contaminated places, recycling sulphur and ammonia N from the air is conceivable.

Directly recycling nutritional ions (salts) from the soil

It is possible to preserve nutrients from eroded topsoil along a field boundary, terrace edge, or area of permanent vegetation, as well as in hollow or flat fields. It can show up as salts, organic debris, and nutritional minerals. Applying less manure or fertilizer to these enriched regions is an option. Both conventional manual farming and contemporary mechanized, data-driven precision farming are based on this premise (using drone images, analysis of colours, GPS location, and many soil analyses). Moreover, deep-rooted, quickly growing plants can absorb nutrients from richer areas and transport them for use as feed, biomass fuel, fruit, or other purposes. Certain mature plants and plant components have low levels of some nutrients, such phosphorus (P). The juvenile component, however, might have larger concentrations. Moreover, trees or shrubs with many uses that fix nitrogen might be blended with plants or shrubs that have a greater P concentration. Western Kenya has conducted research on the subject.

For capturing and recycling nutrients that have leached deeply into the soil, shrubs, trees, long-lasting grasses, and other appropriate plants can be helpful. Moreover, inter-crops, relay intercrops, and surface cover crops can assist recycle nutrients before they are leached and lost. These crops are blended with other crops and grown in a variety of combinations. In Denmark, leaving agricultural fields barren is typically prohibited (without any vegetation cover). As a "catch-crop" for nitrates, even immature plants sown after the summer harvest are suitable. These crops are eliminated in conservation farming or agriculture by plowing, undercutting, or forcing crops downward so that other crops can grow above them.

Recycling of biomass and organic material (as compost)

Terms like "organic matter" and "biomass" are frequently used interchangeably. They include all nutrients, but frequently in insufficient quantities or concentrations, and the nutrients' availability from them might also be an issue. Other articles I've written for this chapter and the series on soil conservation also cover limitations and advantages. This article focuses on workable answers to major problems. Due to the fact that crop leftovers like straw and stalks contain more than 30 times as much carbon than nitrogen, soil microorganisms utilise nitrogen (N) to obtain a balanced meal. With low-nitrogen soil, such a high C:N ratio is problematic. Without sources of nitrogen, composting will go slowly and release a lot of CO2 into the atmosphere. Also, the increase in temperature won't be sufficient to prevent the spread of weeds and other dangerous organisms that unsorted compost might contain. A sufficient amount of nitrogen-fixing legumes can be helpful, but additional phosphate and water are required to boost their effectiveness. Checking moisture, temperature, appearance, and scent using a stick buried deep in the compost pile can be helpful.

Contrary to aerated compost, which allows CO2 to leave rather than produce carbonic acid, wet, weakly aerated compost can become acidic from organic acids that remain in it. Additionally, fresh manure put right next to sensitive roots or seeds might injure plants due to dangerous quantities of, for example, ammonia (NH3) or hydrogen sulfide (H2S). Instead of smelling like rich, lush forest or garden soil, the risk is when it is still fresh or smells like feces or urine. Furthermore, ammonia, methane, and poisonous hydrogen sulfide, which has the aroma of rotting eggs, can be released by livestock feces and urine (H2S). The noxious smell of H2S typically shields individuals from poisoning issues. Although though large containers with slurry or cattle urine are open to the sky, the fumes inside of them are frequently extremely poisonous and deadly to work in. For instance, it is required in Denmark to have adequate storage space, an airtight cover (which may form naturally), and to mix the manure into the soil as soon as it is applied and at the proper rates and times so that the crop may absorb and utilize the nutrients.

Dry compost blends (or surface mulch cover) won't break down like ordinary compost, but they might leak more ammonia to the air. In addition to catching fire or harboring animals like rodents, snakes, or agricultural pests like the large C-shaped dung- or chaffer-beetle-larvae that consume roots and leftovers, dry organic waste can also catch fire. Composting guidelines from a Canadian extension are publicly available. [2]

Yet, by stealing organic stuff, creatures like dung beetles, worms, and others can also profit from organic recycling. Use of a good moist mixture of what is available along with shade, drainage, and/or, at dry sandy locations, a pit will increase biological diversity and activity. You can also add some topsoil and decaying leftovers on top of compost piles. Organic materials and biological activity offer various advantages. By releasing acids or enzymes or by absorbing nutrients, roots and microorganisms can increase the availability of some nutrients in the soil, reducing the concentration in the soil solution. More nutrient-rich minerals are available for release by biological activity in locations where fertilizer has been applied often or where soils are relatively young (regenerated by, for example, ice ages or volcanoes). Yet, compared to temperate regions with entirely distinct soil types and histories of land use, the biologically accessible (within a season) and total (extracted with extreme methods) nutrient content of the soil is significantly lower in many low-income tropical countries. In some tropical soils, the topsoil or the entire root zone is washed clean of weatherable minerals, which can release nutrients. In these old soil types, exchangeable ions, some organic materials, and iron- and aluminum-hydroxidides are often all that are left. The soil types have low levels of exchangeable ions and stronger chemically bonded phosphate at the surface. Similar to sandy soils, they can be mostly silicon dioxide and have poor overall nutrient contents (SiO2). In order to increase or maintain soil fertility, peer-reviewed soil- and agronomy-science and evidence today typically advise taking into account both the application of fertilizer and other methods. In actuality, the attentional focus could be constrained.

Nutrient recycling may be aided through selection and breeding for tolerance to low concentrations of water-soluble nutrients. Some plants exude acids or other compounds from their roots, which aid in nutrient intake by dissolving organic material or minerals.

Dr. T. S. Gahoonia discovered that root hair length (not density) was crucial for P-uptake, and it could easily be used more in plant breeding and selection (pers. comm., Copenhagen, 1996). Lately, it has been shown that root hairs can consume some bacteria, partially digest them, and then recycle some of them (rhizophagy)[3]. Comparable absorption has been observed in rhizobia bacteria prior to nitrogen fixation.

Although surface mulch and contour trash lines can help prevent erosion and water run-off, it's important to take into account the spread of fire, weed seeds, and snakes when planting them. When crushed, materials with lots of fibers and no green components can be used without running the risk of removing too much nitrogen from the soil. Similar to how chewed leaves leave a highly sticky feeling in the mouth, they contain a lot of tannin that binds to proteins and prevents them from releasing nitrogen, at least if they completely coat the proteins. By shading and chilling the soil surface, mulch and shade help to keep it moister, however this will result in an increase in the inefficient portion of light rains' rainfall. Yet, roots that are vital for the uptake of phosphorus and organic matter as well as biological activity benefit from wet topsoil, which also aids in root growth and water infiltration. India offers a free mulch guide [4 HYPERLINK "bookmark:/ ftn4"].

Human and urban waste recycling

Recycling leftovers, feces, and the nutrient-rich urine that contains large concentrations of Nitrogen and other minerals like phosphorous is important for a number of reasons, including the sustainability of phosphate supply and nutrient levels in land-use systems without fertilizer. Nonetheless, it is important to consider cultural, sanitary, and financial concerns. For instance, in rural Africa, cultural objections have been effectively addressed using appropriate techniques like ecological sanitation procedures (search for "EcoSan toilets Uganda") and inclusiveness. Today, deep pit latrines are common in poor nations. While intended to catch flies in mosquito nets on ventilation pipes as the only opening while not in use (search for "Ventilated Improved Pit latrines"), they rarely perform as intended. The material can either be sucked up by a pipe, trenched in the field, and covered right away, or it can first be converted into biogas. If employing a mobile construction, it can also stay covered in soil for six months or more when using other pit latrines that are not deeper than what can be dug up locally. Due to the fact that some parasites and bacteria's resistant life stages can frequently persist longer, especially without oxygen (anaerobic), and survive routine cooking, caution may still be necessary. Yet, it won't come into contact with the majority of crops' edible sections, and the majority of dirt will be removed or cooked. Heavy metals, such as mercury (Hg), cadmium (Cd), or lead (Pb) from batteries, can also provide a problem for recycling garbage, especially in urban or industrialized areas where there is poor waste sorting at the source. Plants can absorb dangerous levels of cadmium, hence it is possible to ban and sort cadmium-containing batteries. View the ash part below as well. Wastewater is mechanically, biologically, and chemically cleansed in Denmark such that N and P can be recycled. The remaining sludge is used for fields and forests with heavy metal content and sanitation requirements. Mechanically settled sludge is used for biogas. The majority of garbage is divided, for instance, into sludge with bone waste remnants and food waste for biogas.

Previous

Next