Principles Of Environmental Science: Soil Conservation PDF

PRINCIPLES OF ENVIRONMENTAL SCIENCE HUGO JACOB Session #7 Soil Conservation Conservation tillage Soil conservation Conservation tillage is an agricultural management approach that aims to minimize the frequency or intensity of tillage operations in an effort to prom...

PRINCIPLES OF ENVIRONMENTAL SCIENCE HUGO JACOB Session #7 Soil Conservation Conservation tillage Soil conservation Conservation tillage is an agricultural management approach that aims to minimize the frequency or intensity of tillage operations in an effort to promote certain economic and environmental benefits. These techniques maintain plant residues on at least 30% of the Experimental field in which conservation tillage with and soil surface after tillage without cover crops are being compared to standard tillage systems. activities Soil conservation Methods of soil conservation called conservation tillage - No-Till - Ridge till - Strip till Experimental field in which conservation tillage with and without cover crops are being compared to standard tillage systems.  Ridge tillage Ridge-till works best on nearly level, poorly drained soils (Waterlogging) The ridges speed up drainage and soil warm-up. Ridge-till systems leave residues on the surface between ridges Strip tillage This type is also known as zonal tillage. The principle’s essence is to divide a field into two parts: seedling and soil management. Second row is just treat with cover crops for conservation tillage systems No till Often the easiest way to provide cover that protects soil from erosion is to leave crop residues on the land after harvest (No till) Crop residues are distributed evenly and left on the soil surface No implements are used (a) to turn the soil over, (b) to cultivate the crops or (c) to incorporate the crop residues into the soil  No till Crop rotation is fundamental to zero-tillage because it helps to minimise weed, insect, and disease populations that increase when the same crop is grown year after year on the same ground. Most experiments with zero-tillage have had increased yields, but in the wetter areas, it took many years to see the crop yields stabilise or increase. Long-Term Tillage Effects on Corn and Soybean Yield in the Piedmont Conservation tillage benefits 1. Increases the soil’s ability to store carbon; 2. Improves the resistance of the ground top layer and reduce air and water erosion; 3. Facilitates the moisture penetration into the soil; 4. Reduces the leaching of nutrients due to the preservation of a large amount of organic matter; 5. Recover unused nutrients and add organic matter to the soil 6. Lowers the moisture evaporation from the ground, which saves the harvest in dry years; 7. Requires less land cultivation.  Conservation tillage challenges Expectations! The overall positive results of cover crop implementation might be a bit obscure. Early benefits such as erosion reduction will be demonstrated quickly; soil health and significant productivity enrichments are likely to take no less than 1 to 3 years and may be somewhat longer. Initial yields could be low in years 1-3, although they have been shown under many conditions to improve in the range of 5% to over 70% after 3 years. Conservation tillage challenges Poor crop sequence planning causes pest spread – insects and disease – happening as a result of using successor plants that may be susceptible to pests harbored in the cover crop. Crop rotation helps to minimize this problem. Added costs and possible delays: seeds, seeding, cover crop termination, and other activities which were not required in the traditional practice will likely occur. Costs may be offset by the benefits Agroforestry Agroforestry definition Agroforestry is generally defined as any land-use system that deliberately integrates woody perennial trees, shrubs, or vines with other crops and/or livestock in an integrated production system. Integration of perennial components can be: › In the same space and time, e.g. rows of grain crops interspersed with rows of trees › In the same space but different times, e.g. rotating between pasture and tree crop production › In different spaces but interacting in time, e.g. adding forest biomass to soil on a crop field Agroforestry definition Agroforestry is agricultural and forestry systems that try to balance various needs: 1) to produce trees for timber and other commercial purposes; 2) to produce a diverse, adequate supply of nutritious foods both to meet global demand and to satisfy the needs of the producers themselves;and 3) to ensure the protection of the natural environment so that it continues to provide resources and environmental services to meet the needs of the present generations and those to come. Unique features of agroforestry as a subset of polyculture systems Defining feature: woody perennial component Leads to these key characteristics: 1. Larger architecture – using more space in 3 dimensions – Modification of micro-environments – Structural complexity – Deeper root systems 2. Longer time horizons – Long life spans – Several years or decades before harvest – Products are often high-value fruits, nuts, timber – Long-term biomass accumulation and carbon sequestration Four common agroforestry practices and their major functions (a) Mixed agroforests of tea (Camellia sinensis) and rubber trees (Hevea brasiliensis) in Xishuangbanna, SW China (b) Silvopasture system with hardwood trees at the Wurdack Farm of the University of Missouri (c) windbreaks in crop fields in Oklahoma (Muschler 2016) (d) riparian buffer consisting of hardwood trees, shrubs, and a mixture of native prairie grasses and forbs at the Bear Creek watershed in Iowa  Riparian buffer system A riparian buffer or stream buffer is a vegetated area (a "buffer strip") near a stream, usually forested, which helps shade and partially protect the stream from the impact of adjacent land uses. Modification of micro-climates Trees can moderate extreme weather for crops growing near them. Example: cooling effect of shade in awalnut orchard in California’s Central Valley. Leafy greens, such as Brassicaspecies, are normally a late fall/early spring crop in this Mediterranean climate, where summers are long, hot, and dry. These farmers are able to extend their harvest season for leafy greens beyond when other farmers in the region are selling them.  Modification of micro-climates Example: windbreaks Wind speed can be reduced by 15% to 75% for a distance from the windbreak up to 20X or more the height of the windbreak In temperate, arid climates, windbreaks reduce turbulent mixing of air, resulting in daytime increases in air temperature of several degrees within a distance of 8X height, and night time increases of 1- 2 deg C up to 30X height. Enhanced field crop growth, and from 6- 44% higher field crops yield (although study results are mixed)  Tree architecture: structural complexity Trees can introduce structural complexity into a landscape dominated by short stature annual crops, providing important wildlife habitat In California’s agriculturally intensive Central Valley, which has lost most of its natural lands, a study found that field margins with hedgerows, tree lines or remnant riparian habitat harbored 2–3 times as many bird species 3–6 times higher maximum total abundances of birds than bare or weedy margins. Significantly greater species evenness (a measure of distribution of individuals amongst different species) Heath et al. 2017. Biological Conservation  Tree architecture: deeper root systems Diverse crops with varying rooting depths – e.g. trees with herbaceous crops - can better utilize water and nutrients from the total volume of soil Tree roots scavenge N and P from deeper in the soil profile, preventing leaching (Jose et al. 2009) Trees in cropland can recycle nutrients from deeper layers to the soil surface via leaf litter (Dosskey et al. 2017) Hydraulic lift: some tree species can redistribute water from deeper, moister soil layers up to drier layers, through their roots, making more soil moisture available to understory plants in arid conditions (Jose et al. 2009) Tree life spans: long-term carbon sequestration The long life spans of trees allows for carbon sequestration that is long enough to “count” in GHG emissions budgets A study in California found that a field edge hedgerow stored 18% of the total carbon on an organic tomato farm, while taking up only 6% of the land area. Smukler et al. 2010. Agriculture, Ecosystems, and Environment Tree life spans and high value products Nuts, tree fruits, and timber often command high prices on the market, allowing higher returns per acre, once past the establishment phase. Agroforestery Permaculture Permaculture Permaculture is an approach to land management and settlement design that adopts arrangements observed in flourishing natural ecosystems.  Permaculture Permaculture uses creative design processes based on whole-systems thinking, considering all materials and energies in flow that affect or are affected by proposed changes. Concept formulated in 1978 by Bill Mollison and David Holmgren in opposition to Western industrialized methods and in congruence with Indigenous or traditional knowledge. Holmgren 12 principles Observe and interact: Take time to engage with nature to design solutions that suit a particular situation. Catch and store energy: Develop systems that collect resources at peak abundance for use in times of need. Obtain a yield: Emphasize projects that generate meaningful rewards. Apply self-regulation and accept feedback: Discourage inappropriate activity to ensure that systems function well. Use and value renewable resources and services: Make the best use of nature's abundance: reduce consumption and dependence on non- renewable resources. Produce no waste:Value and employ all available resources: waste nothing. Holmgren 12 principles Integrate rather than segregate: Proper designs allow relationships to develop between design elements, allowing them to work together to support each other. Use small and slow solutions: Small and slow systems are easier to maintain, make better use of local resources, and produce more sustainable outcomes. Use and value diversity: Diversity reduces system-level vulnerability to threats and fully exploits its environment. Use edges and value the marginal: The border between things is where the most interesting events take place. These are often the system's most valuable, diverse, and productive elements. Creatively use and respond to change: A positive impact on inevitable change comes from careful observation, followed by well-timed intervention. Advantages 1.Sustainability: It is designed to be sustainable, using natural resources to create a self-sustaining ecosystem that can continue to produce food indefinitely. This approach helps to reduce waste and pollution, and it also conserves natural resources like water and soil. 2.Resilience: Permaculture systems are more resilient to climate change and other environmental stresses. The diverse mix of plants and animals in it’s system helps to create a stable ecosystem that can adapt to changing conditions. Advantages 3. Health: Permaculture systems are often healthier for both people and the environment. By avoiding the use of synthetic chemicals, permaculture reduces exposure to harmful toxins and improves the quality of the food produced. 4. Community Building: Permaculture emphasizes the importance of community building and sharing resources. This approach helps to create strong, resilient communities that can work together to support each other. Advantages Increase soil organic carbon, nutrients and biodiversity (Reiff et al. 2024). Mob grazing and Composting What is it? Mob grazing is all about emulating nature, think back to the thousands of bison and wildebeest travelling over vast areas, staying in a tightly knit group for safety. They were eating the fresh grass, dunging and urinating on the area, trampling on much of it before moving on and possibly not coming back to that area for months, even years. Grazing with a high density of stock for a short duration, coupled with a long rest period, is the crux of mob grazing.  Advantages Mob grazing paddocks typically grow tall plants due to the long rest periods between grazing. Moved on after a short period, cattle (or sheep) leave behind between a third and half the forage’, the plants are able to re-grow more quickly. `Drought tolerance – the amount of cover left on the surface not only protects the soil from drying out but because the plants have experienced less severe grazing it allows them to grow deeper roots so they can draw moisture up from much deeper down, making them far more drought tolerant too. Even manure distribution – as the animals graze their way across the paddock they distribute their manure evenly, compared to a set-stocked field where animals often return to a preferred ‘campsite’ to sleep and dung. Less compaction – animals do not have to walk far to search out their next juicy bite, so there is far less compaction from their feet. Also, as mob grazing areas are much smaller than those used for set stocking, their management need not involve driving and risking compaction from farm vehicles.  Advantages Mob grazing is beneficial to the wild flora and fauna too: grazing animals in a ‘mob’ means all the plants get nibbled and this leads to greater diversity in the plant species. Plant resilience & season extension – areas of pasture used for mob grazing grow more robust plants due to the longer recovery periods during which they are not grazed. This leads to increased plant density and deeper more resilient root systems More time with the animals & better animal welfare – as you manage a mob grazing system, you see the animals up close every day without having to drive around a large field trying to find them. Challenges Considerable time to plan is needed or the land can be overgrazed and damaged if move periods or stocking density are not right – the importance of this planning stage should not be underestimated. Time and cost of initial set up of paddocks. This can be done fairly quickly and cheaply using temporary electric fencing, or it can be extensive with replanting of old hedge lines and installing permanent fencing and drinking water Challenges The effectiveness of using livestock management to increase soil C storage has been questioned because some studies show negative effects of mob- grazing on SOM and other desirable rangeland properties. It is likely that multiple interacting factors influence the effects of mob-grazing on SOM including precipitation, soil texture, and species composition of the vegetation (Pineiro et al. 2010). Composting Composting is the natural process of recycling organic matter, such as leaves and food scraps, into a valuable fertilizer that can enrich soil and plants. Anything that grows decomposes eventually; composting simply speeds up the process by providing an ideal environment for bacteria, fungi, and other decomposing organisms (such as worms, sowbugs, and nematodes) to do their work. Benefits of Composting Reduces the Waste Stream Composting is a great way to recycle the organic waste we generate at home. Food scraps and garden waste combined make up more than 28 percent of what we throw away, according to the U.S. Environmental Protection Agency (EPA) Cuts Methane Emissions From Landfills Because our solid waste infrastructure was designed around landfilling, only about 6 percent of food waste gets composted. San Francisco established a large-scale composting program, and by 2000 it was able to divert 50 percent of its waste from landfills. By increasing its goals over the years, San Francisco has been diverting more than 80 percent of waste from landfills since 2012. That means more than 90,000 metric tons of carbon emissions are avoided each year—equivalent to the annual greenhouse gas emissions from 20,000 passenger vehicles Benefits of Composting Improves Soil Health and Lessens Erosion Compost contains three primary nutrients needed by garden crops: nitrogen, phosphorus, and potassium. It also includes traces of other essential elements like calcium, magnesium, iron, and zinc. Instead of relying on synthetic fertilizers that contain harmful chemicals, composting offers an organic alternative. Research has shown the capability of compost to increase soil’s water retention capacity, productivity, and resiliency. Conserves Water Research has shown the water-retaining capacities of soil increase with the addition of organic matter. In fact, each 1 percent increase in soil organic matter helps soil hold 20,000 gallons more water per acre. REGENERATIVE AGRICULTURE No-Soil Agriculture  Hydroponics Hydroponics is the technique of growing plants using a water-based nutrient solution rather than soil, and can include an aggregate substrate, or growing media, such as vermiculite, coconut coir, or perlite. Put simply: Hydroponics is a way to skip the soil, sub in a different material to support the roots of the plant, and grow crops directly in nutrient-rich water. There are multiple approaches to designing hydroponic systems, but the core elements are essentially the same. Hydroponics Hydroponics offers many advantages, notably a decrease in water usage in agriculture. To grow 1 kilogram (2.2 lb) of tomatoes using intensive farming methods requires 214 liters of water; using hydroponics, 70 liters; and only 20 liters (4.4 using aeroponics. Hydroponic cultures lead to highest biomass and protein production compared to other growth substrates, of plants cultivated in the same environmental conditions and supplied with equal amounts of nutrients. Hydroponics advantages 1. Needs No Soil 6. Maximizes Space 2. Conserves Water 7. Produces Higher Yields 3. Facilitates a Micro-Climate 8. Require Less Labor 4. Predictability and Seasonality 9. Shortens the Supply Chain 5. Crops Grow Faster Hydroponics limitations 1. Higher start-up costs compared to soil growing systems. 2. Requires some skills and knowledge to maintain. 3. System failure threats 4. Source of fertilizers?  Aquaponics Aquaponics is a cooperation between plants and fish and the term originates from the two words aquaculture (the growing of fish in a closed environment) and hydroponics (the growing of plants usually in a soil-less environment). Aquaponics Growing fast Aquaponics is considered one of the most efficient and environmentally sustainable farming methods of the 21st century Aquaponic production has been reported to produce six times more yields on one- sixth of space and only require one-sixth of water for production of vegetables. Aquaponics’ Benefits 1. Encompasses two agricultural products (fish and vegetables) being produced from one nitrogen source (fish food) 2. An extremely water-efficient system. aquaponics only needs 1/6th of the water to grow 8 times more food per acre compared to traditional agriculture. 3. Doesn’t require soil and therefore it’s not susceptible to soil-borne diseases 4. Doesn’t require using fertilizers or chemical pesticides 5. Allows a higher control (as it’s easier than soil control) on production leading to lower losses; 6. Can be used on non-arable lands such as deserts, degraded soil or salty, sandy islands Aquaponics’ Weaknesses 1. The high initial start-up costs 2. Aquaponics requires deep expertise in the natural world, farmers need to have knowledge not only on growing vegetables but also on how fish and bacteria work. 3. Mistakes managing the system can quickly cause its collapse Integrated Pest Management Integrated Pest Management Many pest control experts and farmers believe the best way to control crop pests is through integrated pest management (IPM), a program in which each crop and its pests are evaluated as parts of an ecosystem. The overall aim of IPM is to reduce crop damage to an economically tolerable level with minimal use of synthetic pesticides. When farmers using IPM detect an economically damaging level of pests in a field, they start with biological methods (natural predators, parasites, and disease organisms) and cultivation controls (such as altering planting times and growing different crops on fields from year to year to disrupt pests). They apply small amounts of synthetic pesticides only when insect or weed populations reach a threshold where the potential cost of pest damage to crops outweighs the cost of applying the pesticide. Four steps action plan 1. Set Action Thresholds Before taking any pest control action, IPM first sets an action threshold, a point at which pest populations or environmental conditions indicate that pest control action must be taken. Sighting a single pest does not always mean control is needed. The level at which pests will become an economic threat is critical to guide future pest control decisions. 2. Monitor and Identify Pests Not all insects, weeds, and other living organisms require control. Many organisms are innocuous, and some are even beneficial. IPM programs work to monitor for pests and identify them accurately, so that appropriate control decisions can be made in conjunction with action thresholds. This monitoring and identification removes the possibility that pesticides will be used when they are not really needed or that the wrong kind of pesticide will be used. Four steps action plan 3. Prevention As a first line of pest control, IPM programs work to manage the crop, lawn, or indoor space to prevent pests from becoming a threat. In an agricultural crop, this may mean using cultural methods, such as rotating between different crops, selecting pest-resistant varieties, and planting pest-free rootstock. These control methods can be very effective and cost-efficient and present little to no risk to people or the environment. 4. Control Once monitoring, identification, and action thresholds indicate that pest control is required, and preventive methods are no longer effective or available, IPM programs then evaluate the proper control method both for effectiveness and risk. Effective, less risky pest controls are chosen first, including highly targeted chemicals, such as pheromones to disrupt pest mating, or mechanical control, such as trapping or weeding. It Works In Sweden and Denmark, farmers have used it to cut their synthetic pesticide use by more than half. In Cuba, where organic farming is used almost exclusively, farmers make extensive use of IPM. In Brazil, IPM has reduced pesticide use on soybeans by as much as 90%. In Japan, many farmers save money by using ducks for pest control in rice paddies. The ducks’ droppings also provide nutrients for the rice plants. Challenges It requires expert knowledge about each pest situation and takes more time than does relying solely on synthetic pesticides. Methods developed for a crop in one area might not apply to areas with even slightly different growing conditions. Initial costs may be higher, although long-term costs typically are lower than the use of conventional pesticides. Widespread use of IPM has been hindered in the United States and other countries by government subsidies that support use of synthetic pesticides, as well as by opposition from pesticide manufacturers, and a shortage of IPM experts. For the 20/11 You are the experts: - 6 scientific articles related to today’s topics. (Agroforestry,Aquaponics, Permaculture, Conservation Tillage, Composting, IPM) - Present your assigned article as if you published it. - 6 min presentation - 2 min questions (Be ready to answer!)