CMG GardenNotes #246 Making Compost. What Items Should and Should Not be Composted?

Transcription

1 CMG GardenNtes #246 Making Cmpst Outline: What items shuld and shuld nt be cmpsted?, page 1 What is the carbn t nitrgen ratin talked abut in cmpsting literature?, page 2 What is the ideal lcatin fr a cmpst bin?, page 3 What is the ideal size and type f cmpst bin?, page 3 What is the rutine care f a cmpst pile?, page 5 Maintenance, page 6 Trubleshting, page 7 Essential ingredients fr the cmpsting prcess include micrrganisms, rganic matter, water, and air (xygen). The micrbes that cause decmpsitin naturally ccur n plant wastes. Cmpst starters r inculums are nt needed t start decmpsitin. The cmpst needs t be mist t the tuch, but nt sggy (excluding air). Air (xygen) is essential fr the micrbes. T fine f particle size, excessive water, large amunt f sil, and packing f materials may decrease xygen levels. What Items Shuld and Shuld Nt be Cmpsted? Materials t use Leaves Garden debris free f diseases and weed seeds (i.e., carrt tps, chpped crn stalks, pea vines, spent flwers, etc.) Weed, free f seeds Kitchen scraps, free f meat, dairy, fats, and ils Shrub and tree pruning smaller than ne-quarter inch in diameter Hay, straw, and ther plant residues Materials t avid Weeds with seeds; seed may nt be killed if cmpst piles des nt heat t 145 F. Diseased plants, including tmat and ptat vines and ptat peelings. Tree branches great than quarter inch in diameter; large sizes shuld be run thrugh a chipper first, as they will be very slw t decmpse. Meat and dairy prducts, slws decmpsitin and attracts pests Fats, ils, and grease, slws decmpsitin and attracts pests Kitchen scrapes with meat, dairy, fats, ils, r grease 246-1

2 Pet r human feces, may transmit diseases Synthetic r plastic fiber, des nt decmpse Wd ash and lime, drive up the ph f the sil Materials t use in limitatin Large amunts f grass clippings Due the small particle size and high nitrgen, they tend t smell unless mixed with brwn materials. Rather recycle the nutrients back t the grass by nt bagging. Manure Manures may cntain strains f Escherichia cli and ther bacteria that cause human illness. If manure is cmpsted fr fd gardens, a fur mnth curing prcess fllwing cmpsting is necessary t reduce pathgens. Large amunts f plants/weeds treated with pesticides (herbicides, insecticides, and fungicides) Mst pesticides readily break dwn in the cmpsting prcess and present n threat as lng the decmpsitin prcess had been cmpleted. Large amunts f high tannin-cntaining leaves (ak and cttnwd) are als slw t decmpse, but can be used in small quantities if chpped well and mixed with ther materials. Large amunts f juniper, pine, spruce, and arbrvitae pruning Resins in these highly resinus wd and leaf prunings prtect these materials frm decmpsitin and extend the time needed fr cmpsting in cmparisn with ther plant materials. Large amunts f paper prducts Newsprint is best recycled thrugh recycling cllectin peratins rather than cnverted t cmpst. If paper is cmpsted due t a shrtage f dry materials, add n mre than 10 % f the ttal weight f the material being cmpsted. Higher amunts create imbalances in the carbn t nitrgen rati. D nt use clr printed glssy magazines as inks may nt be safe as a sil additive. Large amunts f sil Sme gardeners like t sprinkle small amunts f sil int the cmpst bin as a surce f micrbes. Hwever, this is nt necessary as small amunts f sil are rutinely added with the rts f weeds and ther plants. Large amunts f sil increase weight, decrease xygen infiltratin, and can suffcate micrrganisms. Silless cmpsting is ften practiced. What is the Carbn t Nitrgen Rati Talked Abut in Cmpsting Literature? Fr ptimum prcessing, the rati f carbn t nitrgen in the pile needs t be arund 30 t 1. This is typically fund with the cmbinatin f tw parts green materials with ne part brwn materials. Cmpst piles t high in carbn will be slw t prcess r even nt decmpse. Piles t high in nitrgen develp strng ammnia drs. [Table 1] 246-2

3 Prcessing wrks best if the green and brwn materials are mixed tgether befre adding t the pile. An alternative is t layer the green and brwn materials. Layers shuld nt be mre than tw inches (fine materials) t six inches (carse materials) deep. When nly brwn materials are used, nitrgen fertilizer may be added t supply the needed nitrgen fr decmpsitin. The standard rate is half a cup ammnium sulfate (r equivalent) per bushel f brwn materials. Table 1. Examples f Green and Brwn Materials Green Materials Brwn Materials Vegetable wastes (12 20:1) Dry leaves (30 80:1) Cffee grunds (20:1) Crn stalks (60:1) Grass clippings (12-25:1) Straw (40 100:1) Cw manure (20:1) Bark ( :1) Hrse manure (25:1) Paper ( :1) Pultry manure, fresh (10:1) Wd chips and Pultry manure, with litter (13 18:1) sawdust ( :1) What is the Ideal Lcatin f the Cmpst Bin? Chse a cmpsting site carefully. Cnsideratins include the fllwing: Partial shade avids baking and drying in summer but prvides sme slar heating t start the cmpsting actin. Wind prtectin prevents t much misture lss. Water surce t keep the pile mist but nt sggy. City rdinances ften prhibit cmpst bins within 10 t 20 feet f prperty lines. Cnvenience fr lading and unlading f materials, but away frm yard activities. What is the Ideal Size and Type f Cmpst Bin? Structures are nt necessary fr cmpsting but d help prevent wind and marauding animals frm carrying away plant wastes. Open cmpst piles can be used in less-ppulated rural lcales, but structures are a near-must in urban areas. Many cmpsting structures can be purchased r built. They vary in hw well they can be managed t meet the requirements fr effective decmpsitin under Clrad envirnmental cnditins. Wire and wd structures are cmmn fr hme cmpsting. An inexpensive, easy-t-build type is made frm hardware clth (a stiff, lightweight wire mesh fund in the fencing materials department at many hardware stres). A fur ft high by 13 ft length will make a small bin fur feet acrss. Use wire t hld the length f hardware clth int a rund hp. T unlad the bin, unhk the wires hlding the hp in the circle

4 Structures built f wire dry ut faster, depending n hw expsure t drying winds. Plastic cvers r tarps are ften used t prtect the uter lay frm drying ut. It is remved t add water and plant materials and t aerate the pile. Wd structures d nt dry as much but are generally mre expensive t purchase r build. An inexpensive and easy t build bin is made with fur wd pallets. Use wire and deck screws t fasten sides; add hinges t the frnt sectin t allw fr easy access. Cst runs between $5 and $25. [Figure 1] Figure 1. Simple cmpst bin made with wden pallets fr $5 t $25 An efficient wd structure is the three-chambered bin system that allws plant material t be aerated by turning it frm ne bin t the next as it decmpses. New materials are put in the first bin t begin decmpsitin. After a few weeks, it is turned t the secnd bin fr active decmpsitin. As the prcess naturally slws, it is turned t the third bin fr further curing. [Figure 2] Figure 2. Threechambered cmpst bin build fr $200 t $300 Many brands f small hme cmpst bins are available cmmercially typically running $80 t ver $100. Sme are manufactured frm recycled plastics. They wrk well fr small yards that prduce few plant wastes. [Figure 3] Figure 3. Earth Machine cmpst bin 246-4

5 Size A minimum vlume f material is necessary t build up the heat necessary fr efficient cmpsting. When materials are heavy in green materials, keep the bin smaller t allw fr better aeratin. Three feet by three feet by three feet is cnsidered minimum size t allw fr heating. This small size may be adequate fr small yards with limited materials t cmpst. If cmpsting fall leaves and materials high in brwn materials, a larger bin (5 feet by 5 feet) may keep the prcessing ging thrugh the winter mnths. In-grund pit cmpsting presents prblems with turning r aerating the plant material and als can pl water, which leads t undesirable lw xygen cnditins. What is the Rutine Care f a Cmpst Pile? The breakdwn f rganic yard wastes is a bilgical prcess dependent n micrrganism activity. Like mst living things, these micrbes require favrable temperatures, misture, xygen, and nutrients. Temperature Plant-digesting micrbes perate in a temperature range f 70 F t 140 F, but breakdwn ccurs slwly at the lwer temperatures. Well-managed cmpst rapidly breaks dwn in summer when cmpst temperatures quickly reach 120 F t 130 F. If summer heat plus the heat prduced by active micrbes causes the temperature f the plant mass t exceed 160 F, the micrbes will die. In Clrad winter temperatures, a well-cnstructed 5 ft by 5 ft pile will cntinue prcessing thrugh the cld winter. Smaller piles will cl, stpping micrbe activity and extending the time required t prduce a finished prduct. In the spring, small piles may need t be turned and mixed with additinal materials t enhance prcessing. Misture and xygen Misture and xygen are essential t micrbial activity. In a regin f limited rainfall such as Clrad, add misture regularly t maintain cmpsting. If parts f the cmpsting material dry ut, many micrrganisms in the dry areas die. Even when misture is added, the micrbes that remain require time t multiply and resume plant digestin. The net result is slwer cmpsting. Hwever, excess misture displaces air and slws breakdwn. Surplus water creates lw xygen cnditins where certain micrbes multiply and prduce ful drs. The best descriptin f the prper misture level is mist r damp but nt sggy. The entire mass f plant wastes shuld be mistened unifrmly t the pint where nly a few drps f water can be squeezed frm a fistful f plant material. The size f plant particles that g int the cmpst als affects aeratin. Large particles allw a lt f air t circulate arund the plant chunks, but breakdwn is slw because micrbes can act nly n the utside, nt n the inside f the large chunks. Particles chpped int smaller chunks increase the surface area fr micrbes t perate. Particles chpped t small will cmpact and restrict air flw. Mderate-sized plant pieces f 0.5 t 1.5 inches are the best size t use and can be prduced by hand r machine shredding. Chp wdy materials int a smaller size. Leave sft plant parts in larger pieces fr effective cmpsting. Fluff r turn the material with a pitchfrk r aeratr tl at regular intervals t prvide additinal aeratin and distribute micrbes thrughut the cmpst

6 Nutrients The micrbes that break dwn plants use the plants fr fd. Nitrgen is the mst imprtant fd nutrient, because a nitrgen shrtage drastically slws the cmpsting prcess. Wdy and dried plant materials tend t cntain little nitrgen in cmparisn t the ttal mass f the material. Green plant material, hwever, cntains a high percentage f nitrgen. A mix f tw parts green t ne part brwn material generally gives the best nitrgen balance. Add a plant fertilizer high in nitrgen when green materials are scarce. Maintenance Hw shuld materials be layered in the cmpst pile? Mixing f green and brwn materials befre placing it in the bin speeds decmpsitin. Otherwise, layer green and brwn materials. Des a cmpst pile require turning? N, but turning speeds decmpsitin and turns weed seeds and diseased plants int the center f the pile where temperatures are higher. Use an aeratin tl t reach int the cmpst t lift and mve plant materials. Turn the entire mass ccasinally t prvide unifrm aeratin. What ther rutine care des a cmpst pile require? Keep it mist but nt sggy. If verly wet, it will stink. Being dry stps the activity f micrbes. The cmpst shuld feel mist t tuch. Hwever, it is t wet if mre than a few drps f water can be squeezed ut. Will the cmpst prcess kill plant diseases rganisms and weed seeds? Only if the pile heats abve 145 F and is turned regularly. Few hme cmpst piles heat adequately, thus is it advisable nt t cmpst weeds with seeds and diseased plants. May fresh materials be added t the bin during prcessing? Yes, if small amunts are ccasinally added. Hwever, if a lt f materials are available, it wuld be better t start a new pile rather than cmbining a lt f fresh materials with nearly finished cmpst. Hw can yu tell when cmpst is finished? It will reduce in size by abut half, will have lst the identity f the materials, and will smell earthy. I t typically takes 3 t 9 mnths, depending n type f materials, climatic cnditins, and tending

7 Cmpst Trubleshting Table 2 Cmpst Trubleshting Prblem Cause Slutin Rtten dr Ammnia dr Outside cuple f inches is dry Lw temperature Pests (rats, bears, raccns, insects) Anaerbic cnditins (the lack f xygen) Excess misture Cmpactin Small particle size T much nitrgen (lw C:N rati) Dry Clrad air Pile t small Insufficient misture Pr aeratin Lack f nitrgen Cld weather Presence f meat, dairy, r fatty wastes Turn the pile Make smaller pile Add dry prus materials Mix in brwn materials Nte: If cmpst high in ammnia is used as mulch, it may burn tender fliage. If mixed int sil as an amendment, it can burn rts. Water regularly and cver uter edge with tarp. Make larger pile Add water when turning pile Turn pile t aerate Mix in green materials r add N fertilizer Increase pile size in winter D nt cmpst kitchen scraps with meat, dairy, fats, ils, r grease. Authr: David Whiting, Extensin Cnsumer Hrticulture Specialist (retired). Clrad State University Extensin. Artwrk by David Whiting, used by permissin. Clrad Master Gardener GardenNtes are available nline at Clrad State University, U.S. Department f Agriculture and Clrad cunties cperating. Extensin prgrams are available t all withut discriminatin. N endrsement f prducts mentined is intended nr is criticism implied f prducts nt mentined. Cpyright Clrad State University Extensin. All Rights Reserved. CMG GardenNtes may be reprduced, withut change r additins, fr nnprfit educatinal use. Revised Octber