Module 4 Agriculture PDF

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This material has been reproduced and communicated to you by or on behalf of University of the Philippines pursuant to PART IV: The Law on Copyright of Republic Act (RA) 8293 of the “Intellectual Property Code of the Philippines”. The University does not authorize you to reproduce or communicate this material. The Material may contain works that are subject to copyright protection under RA 8293. Any reproduction and/or communication of the material by you may be subject to copyright infringement and the copyright owners have the right to take legal action against such infringement. Do not remove this notice. © Institute of Environmental Science & Meteorology, College of Science, University of the Philippines Diliman 1 Module 4 University of the Philippines Diliman Agriculture & the Environment © CSPascua  Learning Outcomes ! Discuss the benefits of agriculture to human societies ! Discuss the environmental effects of agriculture ! Explain sustainable agriculture ! Describe alternative agricultural methods & their environmental benefits 3 Agroecosystems agroecosystems differ from natural ecosystems. It converts complex ecosystems of high structural & species diversity to a monoculture of uniform structure, & greatly modifies the soil 4 © CLRingor  disease or a single change in environmental conditions. An Ecological Perspective on Repeated planting of a single species can reduce the soil Agriculture content of certain essential elements, reducing overall soil fertility. Ecological succession is halted to keep the agroecosystem in an early-successional state. Most crops are early- Crops are planted in neat rows & fields (see photo below successional species, which means that they grow fast, left). These simple geometric layouts make crops vulnerable to spread their seeds widely & rapidly, & do best when sunlight, pests since they are exposed. In natural ecosystems, many water, & chemical nutrients in the soil are abundant. Under different species of plants grow mixed together in complex natural conditions, crop species would eventually be replaced patterns, so it is harder for pests to find their favorite crop by later-successional plants. Slowing or stopping natural plants (see photo below right). ecological succession requires time & effort on our part. Agroecosystems require plowing, which is not a natural Biological diversity & food chains are simplified. process. Plowing exposes the soil to erosion & damages its physical structure, leading to a decline in organic matter & a The focus is on monoculture, one plant species rather than loss of chemical elements. many. Large areas are planted with a single species or even a single strain or subspecies. The downside of monoculture is They may include genetically modified crops or organisms that it makes the entire crop vulnerable to attack by a single (GMC/GMO). Botkin & Keller (2011) 5 https://www.worldatlas.com/articles/the-world-leaders-in-coconut-production.html https://today.uconn.edu/2016/05/natural-regrowth-tropical-forest-helps-reach-climate-goals/# Soil carbon cycle. Topsoil underlies all forests & grasslands, as well as The B (subsoil) & the C horizons (parent material) contain most of a croplands. soil’s inorganic matter, mostly broken- Foundation of life on land down rock consisting of varying Most soils that have developed over mixtures of sand, silt, clay, & gravel. long periods of time, called mature Much of it is transported by water Soil is the natural medium for the soils, contain horizontal layers, or from the A horizon. The C horizon lies growth of plants. It consists of layers horizons, each with a distinct texture & on a base of parent material, which is (soil horizons) composed of weathered composition that vary with different often bedrock. mineral materials, organic material, air, types of soils (see figure on next water, & billions of living organisms, page). Most mature soils have at least The spaces, or pores, between the most of them microscopic three of the four possible horizons. solid organic & inorganic particles in decomposers. Soil is the end product the upper & lower soil layers contain of the combined influence of climate, The roots of most plants & the majority varying amounts of air (mostly N2 & O2 topography, organisms (flora, fauna & of a soil’s organic matter are gas) & water. Plant roots use the human) on parent materials (original concentrated in the soil’s two upper oxygen for cellular respiration. As long rocks & minerals) over time (FAO). layers, the O horizon of leaf litter & the as the O & A horizons are anchored by A horizon of topsoil. In healthy soils, vegetation, the soil layers as a whole Soil formation begins when bedrock is these two layers teem with bacteria, act as a sponge, storing water & slowly broken down into fragments & fungi, earthworms, & small insects, all nutrients, & releasing them in a particles by physical, chemical, & interacting in complex food webs. nourishing trickle. biological processes, called Bacteria & other decomposer weathering. Soil, on which all microorganisms break down some of Although topsoil is a renewable terrestrial life depends, is one of the the soil’s complex organic compounds resource, it is renewed very slowly, most important components of the into a mixture of the partially which means it can be depleted. Just earth’s natural capital. It supplies most decomposed bodies of dead plants & 1 cm of topsoil can take hundreds of of the nutrients needed for plant animals, called humus, & inorganic years to form, but it can be washed or growth & purifies & stores water. materials such as clay, silt, & sand. blown away in a matter of weeks or Organisms living in the soil remove Soil moisture carrying these dissolved months when we plow grassland or carbon dioxide from the atmosphere & nutrients is drawn up by the roots of clear a forest & leave its topsoil store it as organic carbon plants & transported through their unprotected. compounds, thereby helping control stems & into their leaves as a key the earth’s climate as part of the component of chemical cycling. Miller & Spoolman (2016) 6  ell as croplands. mixtures of sand, silt, clay, and gravel. How does soil contribute to each of ils that have developed over Much of it is transported by water the four components of biodiversity s of time, called mature soils, from the A horizon. The C horizon lies described in Figure 4.2 (p. 65)? izontal layers, or horizons A), each with Oak Fern exture and Moss and Organic tree Millipede n that vary lichen debris Honey Rock Grasses and fungus Earthworm ent types of fragments small shrubs Wood mature soils sorrel st three of the O horizon le horizons. Leaf litter A horizon ts of most Topsoil the majority Mole organic matter Bacteria trated in the B horizon Subsoil D FIGURE 10.A soil profile Fungus on of soil. C horizon : What role do Parent material e tree in this Bedrock in soil forma- Immature so Mite might the soil il Young soil rocess change Mature soil ere removed? Nematode Root system earning Red earth mite Beetle larva Generalized soil profile & formation of soil. The biosphere, geosphere, atmosphere, & hydrosphere all contribute together to form soil. Image adapted from Miller & Spoolman (2016). 7 opyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). al review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. genetic diversity through monoculture agriculture (Crist et Major Environmental 8/13/14 8:42 AM al., 2017). It is largely responsible for the world’s 400 dead zones. Dead zones are hypoxic (low-oxygen) areas in the Effects of Agriculture world's oceans & large lakes, caused by "excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life Industrialized agriculture has greater overall harmful in bottom and near-bottom water. At least 50% of world’s environmental effects than any other human activity, which species-rich wetlands were drained largely for agriculture, & may limit future food production (Miller & Spoolman, 2016). aquaculture drive mangrove decline (see photo below right). One of these environmental effects is biodiversity loss Coastal seas are critically endangered due to overfishing, (review lecture on Biodiversity) resulting from habitat loss & now trawlers turned to deeper waters. Small fishes are not degradation from clearing forests (see photo below left) & only harvested for human consumption but also for feeds grasslands, & draining wetlands; fish kills from pesticide for large-scale aquaculture & livestock operations. There is runoff; killing of wild predators to protect livestock; & loss of also a high risk of extinction of large ocean animals due to Forest cut to make way for an oil palm plantation in Papua, Indonesia in April 2018. Image Fishponds in former mangrove areas, Philippines. Image retrieved from https:// credit: Ulet Ifansasti/Greenpeace https://e360.yale.edu/features/conflicting-data-how-fast- www.zsl.org/blogs/conservation/returning-ponds-to-mangrove-forests-in-the-philippines is-the-worlds-losing-its-forests 8  gency it deserves not only will help on the implausible idealization when trends are tallied. fertility is 2.2 (59). These figures signal front FIGURE 2.1 of ecological challenges but also advances ensuring educational opportunities for girl Global solutions human rights, especially women’s and children’s women can move the world more swiftly to The world is demographically diverse. Many re-LANDrights AREA (23, BY MAJOR LAND-USEwomen 28). Wherever CLASS,are 2010 empow- a smaller population. Indeed, achieving ful gions are experiencing moderate to rapid growth, ered educationally, culturally, economically, der equality would, in all likelihood, eventuall while developed countries and industrial fishing. On land, steep population declines of big several emerging politically, 100% and legally, fertility rates fall (59). to global fertility below—and possibly well bel economies have entered herbivores & carnivores are linked to crop & animal a phase of low to negative Populations tend to move toward states of zero the replacement value of roughly 2.1 chil growth (98). Despite this diversity, a common or 80% negative growth when women achieve equal Such a development could result in a popu agriculture (Crist et al., 2017). thread links policies promoting ecologically as standing 60% with men, as long as family planning trajectory even lower than the United Nations PERCENT well as socially sustainable population change services and contraceptives are readily available variant” projection, which suggests a popul worldwide.is the major driver of deforestation Agricultural expansion (13).40% Female education has been singled out as peak at 8.7 billion in mid-century (111). globally, & agricultural, A commonplaceforestry &misperception land policies are oftenpop- is that at key. Although other factors play important roles, As women achieve full equality and fe 20% odds (FAO, 2016). ulationA growthstudy bywill FAO revealed resolve that itself as in 2010 economic the number of years of a girl’s or woman’s edu- declines follow, societies tend to move thro (see figure ondevelopment the right, above), about 38%encourage and urbanization of the world’s smaller 0% cation, on average, varies inversely with the num- period where the elderly population bec land area wasfamilies used for (99).agriculture while roughly Several 20th-century cases,31% was however, ber of children Africa she willAsia Europe have (108–110). North Oceania large relative South to theWorld active workforce. This and Central America allocated for demonstrate forest. Asia has the highest the efficacy proportionpolicies of population of MakingAgricultureeducation Forest for girlsOther and women Americaan present challenges for public pensions agricultural land (52%) & the in reducing lowest fertility in proportion the absence of of forest strong ambitiously pursued international policy is laud- healthcare programs (98). But these chall (19%). Europe, has thedevelopment economic lowest proportion (100). Suchof agricultural able policies simul-Note: “Other The in land” itself as well is all land not proportions as of categorizedpivotal the total land for as agricultural the future or forestby area occupied land. of are tractable agriculture, forests & other land(112), usesand in when they arise the land (21%) & taneously the second-highest promote human proportion rights andof forest support im-SOURCE: FAO, 2015a, various 2016a.of the world, as of 2010. Image adapted from FAO, 2016. regions best faced directly rather Net annual tha average c (46%). Their portant study also showedgoals. development that from Lessons2000-2010, from successful in forest area, 2000−2 reverting to pronatalist pol most of the 33 countries population & territories strategies indicatingasnet in countries lossesas diverse Each country will need to ad FIGURE 2.2 Net annual average c in forest areaThailand, & net gains in agricultural Bangladesh, CostaareaRica,are in Africa, South Korea, potential problems accompan in agricultural area, 2 South & Central America, & South & SE Asia (see figure onNET ANNUAL AVERAGE CHANGE IN FOREST AND AGRICULTURAL LAND, BY and Iran, among others, reveal that the most ef- an aging population accordi the next page).fective transcultural Cambodia, approach Indonesia, to lowering fertilityCLIMATIC DOMAIN, 2000–2010 Myanmar, its specific economic, social rates is to embark on comprehensive, Philippines, Sri Lanka, & Thailand have a combined net well-designed, 8 000 cultural circumstances. Gener and well-funded campaigns that forest loss of 10,562 ha & a net agricultural gain of 13,484 support that pur- proaches include encouraging h pose while simultaneously ha. In another study, the agricultural expansion & declines promoting women’s 6 000 savings rates, extending the r and overall well-being (13, in forest cover in Neotropics, Africa, & SE Asia threatened 27). ment age, raising taxes, and sh 4 000 Wherever human rights–promoting policies 60% of primate species with extinction while 75% of them Net annual average change to to governmental food policie lower fertility rates have been have already declining population (see figure on the right, implemented, birth in forest area, 2000−2010 2 000 support longer but also hea 000 HA below). rates have declined within a generation or two. and more productive lives. 0 Policies include prominent public discourse on Net annual average change in agricultural area, 2000−2010 tionally, in a century where the issue; prioritizing the education of girls and -2 000 stantial movements of peopl The irony is that with biodiversity losses, we also lose women; establishing accessible and affordable all but certain in response t pollinators, which familyare responsible planning for assisting services; provisioningover modern 80% of -4 000 vironmental degradation an the world's flowering 8 000 plants to reproduce contraceptive methods through diverse outlets; (US Forest -6 000 Boreal mate change, as well as econ Service). Without 6 000 them,health deploying our diets wouldforbegrassroots workers severely limited, educa- Fig. 3. Agricultural Agricultural expansion &expansion forest cover declineand declines in Neotropics,in Africa, forest& SEA Temperate cover dislocation Asia threatens as muchand conflict, neg & it would betion more SOURCE: FAO, 2015a, 2016a. anddifficult to making acquirecounseling the varietyfor of couples vitamins -8 000 support; as 60% of primate (1990–2010) species with in primate rangeextinction. regions. Graph adapted Sixty Boreal from percent Crist of et Subtropics al. (2017); primate Temperate population photos Tropicsgrowth in devel Subtropics & minerals that 4 000 we need to stay healthy. retrieved from https://www.nytimes.com/2017/01/18/science/almost-two-thirds-of-primate- available; eliminating governmental incentives species are threatened with extinction and 75% have declining Tropics nations could encourage gr FIGURE species-near-extinction-scientists-find.html 2.3 for large families; and making sexuality educa- 2 000 populations. [Source: (69); original data source: FAOSTAT.] tolerance toward immigratio 000 HA tion mandatory in school curricula (101). lowances and thus less politic 9 0 NET ANNUAL AVERAGE FOREST AREA CHANGE, BY CLIMATIC DOMAIN (000 ha per year) High priority on the international agenda heaval around this sensitive must -2 000 be that people everywhere have ready 6 000 (113). At the same time, by prio access and unhindered agency to use family ing strategies for slowing or en -4 000 4 000 ANNAUL FOREST CHANGE (000 ha) FIGURE 2.8 FIGURE 2.8 planning services and contraceptive technolo- population growth in rapidly g gies, NET CHANGES IN AGRICULTURAL along AND -6 000 FORESTwith counseling AREA, to assist individuals’ BY COUNTRY/TERRITORY, 2000–2010 2 000 ing countries, the resulting econ and couples’ preferences (102). International 0 and environmental dividends -8 000 funding for BorealfamilyTemperate planning Subtropics declined inTropics the Boreal will counter pressures on peo past two decades, even though the financial Temperate -2 000 emigrate. backing to bring services that allow women Subtropics -4 000 Pursuing policies that will c to control their fertility has been pivotal in conditions encouraging the d GRAPHICS: ADAPTED BY H. BISHOP/SCIENCE Tropics -6 000 countries where fertility rates have fallen (103). eration of the global population Reversing the recent shortfall and investing -8 000 alone not suffice to stave of financially and in technology transfer in this diversity destruction and other -10 000 space are crucial, 6 000and developed nations should 2000−2015 2000−2005 2005−2010 sing ecological problems. Addre 2010−2015 SOURCE: FAO, 2015a. lead on this front (104). Additionally, priori- excessive consumption world 4 000 ANNAUL FOREST CHANGE (000 ha) tizing the avoidance of unintended pregnancies Fig. 4. Estimated proportions of unintended pregnancies calls for such actions as purs in all nations is 2 000crucial. Unplanned pregnancies (those not planned or wanted by the pregnant women in the efficiency gains and conserv are globally pervasive, and in the Americas they next 2 years or longer) vary from one-third | 13 | to more than in energy and materials use; 0 may account for more than half of all pregnancies one-half worldwide. Source: (105). ing from fossil fuels to renew -2 000 -4 000356, 260–264 (2017) Crist et al., Science 21 April 2017 4 -6 000 -8 000 -10 000 2000−2015 2000−2005 2005−2010 2010−2015 NET GAIN IN AGRICULTURAL AREA, NET LOSS IN FOREST AREA NET GAIN IN FOREST AREA, NET LOSS IN AGRICULTURAL AREA NET LOSS IN FOREST AND AGRICULTURAL AREA NET GAIN IN FOREST AND AGRICULTURAL AREA NO OR SMALL CHANGE IN THE AREA UNDER BOTH LAND USES NO DATA AVAILABLE SOURCE: FAO, SOURCE: FAO, 2015a, 2015a, 2016a. 2016a. The various combinations of net gains or losses in forest & agricultural areas, by country/territory worldwide, in the period 2000–2010. Image adapted from FAO, 2016. | 18 | | 19 | 10  Agriculture also contributes about 23% of all human-induced to desert land due to soil exposure. Lands undergoing greenhouse gas emissions, with the livestock sector desertification have progressive loss of mature, stabilizing representing 14.5% of such emissions (UNEP). Past vegetation, or loss of crop cover during period of drought or estimates have also suggested that 2.5% of human-induced economic infeasibility, & loss of topsoil. Erosion by wind & climate warming can be attributed to rice farming (Kritee et water then winnows the fine-grained particles in the soil, al., 2018). The main culprit is methane, a potent greenhouse which may result to dust storms such as the 1930s Dust gas emitted from flooded rice fields as bacteria in the Bowl in American mid-west (see figure on the next page). waterlogged soil produce it in large quantities. However, there is another gas produced by rice fields that can have a Water depletion & pollution may also arise because of harmful climate effect. Nitrous oxide, commonly known as intensive agriculture. Approximately 80% of freshwater laughing gas, is also produced by soil microbes in rice fields. resources is used for irrigation & livestock drinking as well as Moreover, agricultural activities also cause other pollutants to grow feed for livestock & to wash away their wastes (Crist from fossil fuel use & pesticide sprays to be released in the et al., 2017). Water bodies may be contaminated with atmosphere (Crist et al., 2017). pesticides & fertilizers, resulting to overfertilization of lakes (eutrophication) & ultimately fish kills. Eutrophication may Another major environmental effect of agriculture is soil also occur due to excess fish feeds in aquaculture systems, erosion. It is the movement & transport of soil by various which introduces extra N & P directly into the water (Talbot & agents (i.e., water, wind, & mass movement). It is a natural Hole, 1994). Rivers, lakes, & seas may also become polluted process that can be exacerbated by human activities (e.g. with sediment due to soil erosion. Furthermore, flooding through plowing or tilling). Soil erosion has been considered may happen because of increased runoff as a result of soil as the primary cause of soil degradation because soil degradation. erosion leads to the loss of topsoil & soil organic matter, which are essential for the growing of plants. The outcome is Human health is also affected by agricultural activities. loss of fertility, hence reduced crop yield. In addition, as the Drinking waters contaminated with nitrates from fertilizers soil is washed away, it also pollutes adjacent waterbodies cause baby blue syndrome (methemoglobinemia). Pesticide with sediments, nutrients, & agrochemicals. Soil residues in water, food, & air are potentially toxic to humans salinization is also one of the effects of agricultural activities. & can have both acute & chronic health effects such as Irrigation water contains dilute solution of various salts. When cancer, pulmonary & hematological morbidity, inborn irrigation water is not absorbed, it evaporates & leave salts. deformities & immune system deficiencies (UNEP, 1993). This is widespread especially in dry climates. Another Drinking & swimming waters may be contaminated with outcome is desertification, when fertile lands are degraded disease organisms from livestock wastes. Bacterial contamination of meat may also occur. 11 The 1930s Dust Bowl in the midwestern USA was a result of combined intense plowing & major drought, which loosen the soil. About 100 M acres of farmland were affected (in comparison, the Philippines’ land area is only 74 M acre) & 2.5 M people migrated. (A) Wild ducks choked to death on the dust. The area was once a watering stop on their spring migrations. Photo credits: A & C from http://time.com/3878664/dust-bowl-photos-from-an-american-catastrophe/; B from http://www.earthmagazine.org/article/return-dust-bowl, & D from http://www.pbs.org/kenburns/dustbowl/photos/ A B C D 12  BetweenBetween 2000 and 2000 2025, and scientists 2025, scientists estimate, estimate, the worldthe popula- world popula- tion from tionirrigated from irrigatedwater another water another 500 billion m3, forma3,total 500 billion for aoftotal of 3 3 tion will tion increase will increase from 6.6 frombillion 6.6 billion to 7.8 billion, to 7.8 billion, approximately approximately 13,800 13,800 billion m of water billion m ofper water yearper foryear foodfor production, food production, or 20%or 20% double double what it whatwas init1974. was inTo 1974. keepTo pace keepwithpace thewith growing the growing popu- popu- of the water of theevaporated water evaporated and transpired and transpired worldwide. worldwide. By 2025, Bythere- 2025, there- lation, lation, the United the United NationsNations Food and Food Agriculture and AgricultureOrganization Organization fore, humans fore, humanswill be will appropriating be appropriatingalmost almosthalf of half all the of all waterthe water predicts,predicts, that food thatproduction food production will have willtohave double The to double Aral by 2025, byand Sea 2025, and Disaster availableavailable to life on toland life on forland growing for growing food forfood theirfor own their use.ownWhere use. Where so will sothewill amountthe amount of waterofconsumed water consumedby foodby crops. Thefood Will crops. Aral SeatheWill will the the is located inwill additional the additional Central waterbetween Asia, come waterfrom? come from? the Southern part of Agriculture is central to fostering supply supply of freshwater of freshwater be ablebe to able meettothismeet increased thisKazakhstan increased demand, demand, or or Although Although the amount the amount of & Northern Uzbekistan. It was once the 4th largest saline rainwater of rainwater cannot cannot be increased, be increased, lake in economic growth, reducing poverty, & will thewill waterthesupply water limit supplyglobal limitfood globalproduction? food production? the world. In the it 1960s, can be it the can used be Soviet more used efficiently more government efficiently through decided through farming to divert farming methods the methods rivers such that such more importantly improving food security. Measures Growing Growing aimed crops at consume crops consume water through water through transpiration feedtranspiration the lake(lossso that as they (loss terracing, ascould terracing, mulching, irrigatemulching, theand contouring. desert and contouring. region Forty percent surrounding Forty the percent ofSeathe inof the of waterof from water addressing these essentials need not leaves from as leaves part as of part the photosynthetic of the order photosynthetic to process) favor agriculture process) and global and rather food global than harvest food supply harvest now the comes now Aral from comesSea basin. irrigated from Although irrigated land, and land,someand some evaporation evaporation from cause environmental degradation. It plant from andplantsoil andsurfaces. soil surfaces. The irrigation volume The volume of made waterof the dessert scientists water bloom, scientists estimate it devastated estimate that thethat volume the the Aral volume of Sea. irrigation of These irrigation water series available water of available is ironic thatconsumed the consumed by crops natural byworldwide—including capital crops worldwide—including rainwater Google rainwater Earth and irrigated satellite and irrigated images to crops towill show cropshave willthe tohaveshrinking tripletobytriple Aral by Sea. 2025—to 2025—to a volume a volume equaling equaling 24 24 3 3 26 26 required towater—is sustainwater—is estimated agriculture estimated at -3,200 land, atbillion 3,200 m per m billion year.perAnyear. almost An equal almost equal Nile riversNileorrivers 110 or Colorado 110 Colorado rivers. rivers. A significantA significant saving of saving wa- of wa- air, water, amount amount of water-ofare & biodiversity iswater used theisby used onesotherbyplants other in plants and innearandagricultural near agricultural ter can ter therefore can therefore come from comemore fromefficient more efficient irrigation irrigation methods, methods, 3 3 1973 1984 1994 fields. Thus, fields. it being degraded. Most of all, humanThus, takes it 7,500 takes billion 7,500 m billion per m year per of year water oftowater supplyto supplysuch as such improvedas improved sprinkler sprinkler systems, systems, drip irrigation, drip irrigation, night irriga- night irriga- health maycrop alsoecosystems be cropnegatively ecosystems around aroundthe world the(see worldTable(see11.2). Table Grazing 11.2). Grazing and and tion, and tion,surge andflow.surge flow. impacted.pastureland We are faced pastureland account with theanother account for for another 5,800 billion m3, andmevapora- 5,800 billion 3 , and evapora- Surge flow Surgeis flowthe intermittent is the intermittent application application of water of along water along challenge of feeding the world & at furrows—on furrows—on and offand periods off periods of waterofflow waterat flow constantat constant or vari-or vari- the same time protecting our natural able intervals.