אדמה

כרום Luvisols: 100%
הקינכט

הזדמנות	עומק	ביוב	תגובת מרקם - ה-pH	פחמן אורגני מוליכות - חשמל	קטיון תשתית חילופי	קטיון חימר החליפין	סידן פחמתי - סיד	Gypsum Sodium - בר-המרה
	רובד קרקע עליון	3	6.4	0.86	12	38	0	0
	תשתית	3	6.4	0.38	15	40	0	0

משולש אדמה - כרום Luvisols

תמונות - כרום Luvisols

הגדרה - כרום Luvisols

Luvisols έχουν συνήθως καφέ έως σκούρο καφέ ορίζοντα επιφάνεια πάνω από ένα (γκρι), καφέ με ισχυρή καφέ ή κόκκινο argic υπόγειο ορίζοντα. Χρωμικού υποδηλώνει την ύπαρξη εντός των 150 εκατοστών από την επιφάνεια του εδάφους ένα υπόγειο στρώμα, 30 cm ή περισσότερο πυκνή, που έχει μια απόχρωση Munsell πιο κόκκινο από 7,5 YR ή που έχει και τα δύο, ένα χρώμα των 7,5 YR και χρώματος, υγρό, πάνω από 4. Στο υποτροπικό Luvisols ειδικότερα, calcic ορίζοντα μπορεί να είναι παρόντες ή τσέπες από μαλακό φρέσκο ασβέστη συμβαίνουν μέσα και κάτω από ένα καφεκόκκινο argic ορίζοντα. Τα χρώματα του εδάφους είναι μικρότερο σε κοκκινωπό Luvisols σε ψυχρές περιοχές από ό, τι σε θερμότερα κλίματα. Σε υγρά περιβάλλοντα, η επιφάνεια του εδάφους μπορεί να εξαντληθούν από πηλό και δωρεάν οξείδια του σιδήρου, στο βαθμό που ένα γκρίζο ορίζοντα eluviation μορφές κάτω από ένα σκοτεινό, αλλά λεπτό A-ορίζοντα. Luvisols εκτείνεται σε 500 - 600000000 εκτάρια παγκοσμίως, κυρίως στις εύκρατες περιοχές, όπως στα δυτικά και το κέντρο της Ρωσικής Ομοσπονδίας, των Ηνωμένων Πολιτειών της Αμερικής, και της Κεντρικής Ευρώπης, αλλά και στην περιοχή της Μεσογείου και της νότιας Αυστραλίας. Στις υποτροπικές και τροπικές περιοχές, Luvisols συμβαίνουν κυρίως στους νέους επιφάνειες γης. Οι περισσότεροι Luvisols είναι εύφορα εδάφη και είναι κατάλληλο για ένα ευρύ φάσμα των γεωργικών χρήσεων. Οι Luvisols στην εύκρατη ζώνη καλλιεργούνται ευρέως μικρούς κόκκους, ζαχαρότευτλων και κτηνοτροφικά? Σε επικλινείς περιοχές, που χρησιμοποιούνται για τα δάση οπωρώνες, ή / και βόσκηση. Στην περιοχή της Μεσογείου, όπου Luvisols (πολλοί με το χρωμικό, calcic ή vertic προκριματικό) είναι κοινά σε colluvial καταθέσεις του ασβεστόλιθου καιρικές συνθήκες, οι χαμηλότερες πλαγιές ευρέως σπαρθεί με σιτάρι και / ή τα ζαχαρότευτλα, ενώ οι συχνά διαβρώνονται άνω πλαγιές που χρησιμοποιείται εκτεταμένα για βόσκηση ή να φυτεύονται δενδρώδεις καλλιέργειες

[1]

תאור - טין

Loams είναι τα πιο χρήσιμα "all around" εδάφη? Συνδυάζουν την ελαφρότητα και την πρωιμότητα της άμμου, με τη δύναμη και retentiveness των αργίλων. Loams περιέχουν από 40 έως 60 τοις εκατό, της άμμου, και 15 έως 25 τοις εκατό, από πηλό. Οι "εργασία μέχρι" εύκολα, δεν κρούστα ή κρακ, είναι καλά εξοπλισμένη με τα τρόφιμα φυτικής, και, κυρίως ποια είναι σημαντικό, το νερό κινείται ελεύθερα μέσα από αυτά και ακόμα δεν είναι leachy. Σχεδόν όλες οι γεωργικές καλλιέργειες αναπτύσσονται ικανοποιητικά σε μάργες. Είναι ιδιαίτερα κατάλληλο για τις πατάτες, το καλαμπόκι, την αγορά κηπουρική καλλιέργειες, και τα μικρά φρούτα? Αλλά χόρτα, σιτηρά, τριφύλλι, μηδική, και το βαμβάκι, βρίσκουν συμπαθής. Δεν απαιτεί καμία ιδιαίτερη μεταχείριση, εκτός εάν η προσοχή στην καλή όργωμα, αποστράγγιση, και την προσθήκη του χούμου που είναι ένα απαραίτητο μέρος της βέλτιστης πρακτικής αγρόκτημα παντού. Δεν έχει σημασία αν πιπεριές που καλλιεργούνται στις εύκρατες, τροπικές ή υποτροπικά κλίματα για όσο διάστημα έχουν μια σχετικά στεγνή εποχή, οπότε μια καλή μάργες που στραγγίζει καλά βοηθά να αντισταθμίσει ένα κλίμα πιο υγρές. Οι περισσότεροι οπωροφόρα δέντρα ζουν περισσότερο και να παράγουν καλύτερα όταν μεγαλώνουν σε ισορροπημένη μάργες. Εσπεριδοειδή ήθελα καλή αποστράγγιση, αλλά θα πρέπει να διατηρείται υγρό. Πηλός είναι μια καλή επιλογή για τα εσπεριδοειδή

[2]

יבולים - כרום Luvisols

גרגרים קטנים, סלק סוכר, מספוא (אזור ממוזג)
מטעים (אזורים משופעים)
חיטה, סלק סוכר (מדרונות נמוכים, אזור הים התיכון), גידולי עץ (מדרונות העליונים, אזור הים התיכון)

[3] [4]

מדדים/דיון

נושא	ערך	פרטים
ביוב	3	רקע אדמה עם מעט רק לכתמים מנומרים כתומים נפוצים מציינת את האדמה בינונית מנוקזת היטב מים עוברים דרך האדמה באיטיות במהלך כמה תקופות של השנה המים חופשיים פנימיים הוא עמוקים במתינות ועשויים להיות חולף או קבוע The soil is wet for only a short time within the rooting depth during the growing season The soil often has a moderately low or lower saturated hydraulic conductivity class within 1 meter of the surface, or the soil experiences periods of high rainfall, or both הגדרה Drainage Class soils refers to the frequency and duration of periods when the soil is saturated with water. Alterations of the water regime by human activities, either through drainage or irrigation, are not a consideration unless they have significantly changed the morphology of the soil. Seven classes of natural soil drainage are recognized 1. very poorly drained 2. poorly drained 3. somewhat poorly drained 4. moderately well drained 5. well drained 6. somewhat excessively drained 7. excessively drained [5] [6]
התייחסות אדמת עומק	100 mm	האתגרים מגבלות עומק אדמה עלולות להשפיע על חדירת שורש ועלולות להגביל את היווצרות תשואה בשורשים ופקעות [7] [8] הגדרה An approximation of actual soil depth can be derived through accounting for relevant depth limiting soil phases, obstacles to roots and occurrence of impermeable layers. Soil depth limitations which affect root penetration and may constrain yield formation (roots and tubers). This is a measurement in cm of reference soil depth. Reference soil depth of all soil units are set at 100 cm, except for Rendzinas and Rankers of FAO-74 and Leptosols of FAO-90, where the reference soil depth is set at 30 cm, and for Lithosols of FAO-74 and Lithic Leptosols of FAO-90, where it is set at 10 cm [7] [9]
בסיס הרוויה	89%	האתגרים יכולת חדירה נמוכה ההשקיה לא ניתן חקלאות מוגבלת לגידולים סובלניים אל פני השטח waterlogging (למשל אורז, עשבים) הפריון נמוך Strongly alkaline soils are often highly sodic (Na reaching toxic levels), badly structured (columnar structure) and easily dispersed surface clays מעל ה- pH של 7.5 (מאוד בסיסי), כמה חומרים מזינים כגון ברזל, מנגן, והזרחן פחות זמינים טיפים כדי להוריד את רמת חומציות קרקע, להוסיף מקור של חומצה, כגון עלים גרוסים, גופרית, נסורת או כבול רקע ערך הרוויה הבסיס לעתים קרובות מראה קשר לינארי קרוב עם pH הרוויה בסיס> 80% מצביעים על תנאי קרקע רוויים לעתים קרובות גיר, לפעמים sodic או מלוחים [7] הגדרה The base saturation of the topsoil measures the sum of exchangeable cations (nutrients) Na, Ca, Mg and K as a percentage of the overall exchange capacity of the soil (including the same cations plus H and Al). The value often shows a near linear correlation with pH. Critical values as follows Base Saturation < 20 % = desaturated soils, similar interpretation as extremely acid pH Base Saturation of 20 – 50 % = acid conditions Base Saturation of 50 – 80 % = Soil conditions of neutral to slightly alkaline which are ideal conditions for most crops Base Saturation > 80% indicates saturated conditions often calcareous, sometimes sodic or saline [7] [8]
CaCO3 סידן פחמה - סיד	0% משקל	רקע רמות נמוכות של סידן פחמתי לשפר את מבנה הקרקע מועילים בדרך כלל לייצור היבול [7] [10] הגדרה This gives the calcium carbonate (lime) content in the topsoil. Calcium carbonate is a chemical compound (a salt), with the chemical formula CaCO3. It is a common substance found as rock in all parts of the world, and is the main component of shells of marine organisms, snails, and eggshells. Calcium carbonate is the active ingredient in agricultural lime, and is usually the principal cause of hard water. It is quite common in soils particularly in drier areas and it may occur in different forms as mycelium-like threads, as soft powdery lime, as harder concretions or cemented in petrocalcic horizons. Low levels of calcium carbonate enhance soil structure and are generally beneficial for crop production but at higher concentrations they may induce iron deficiency and when cemented limit the water storage capacity of soils. In agronomic sense relevant limits are None to very low < 2 Low = 2 – 5 Moderate = 5 – 15 High = 15 – 40 Very High > 40 [7]
פחמן אורגני	0.86% משקל	האתגרים פחמן אורגני כללי בקרקעות מינרלים (באחוזים): 1 עד 5 = רמות נאותות, <1 = יכול להצביע על אובדן אפשרי של C האורגני משחיקה או תהליכים אחרים, במיוחד באזורים ממוזגים או קרים [11] [12] [7] [13] [14] [15] טיפים להגדיל את תכולת חומר האורגנית על ידי החזרת חומרים אורגניים בקרקעות והוספת סיבובים עם גידולים גבוהים שאריות וגידולים עמוקות או צפופה-השתרשות Ways to increase organic matter contents of soils: compost, cover crops/green manure crops, crop rotation, perennial forage crops, zero or reduced tillage, agroforestry [11] [12] [7] [13] [14] [15] רקע פחמן אורגני הוא, יחד עם pH, המחוון הפשוט ביותר של מצב הבריאות של האדמה בינוני עד גבוהה פחמן אורגני בקרקע (SOC) בקרקע הוא אינדיקטור של יבולים גבוהים Moderate to high amounts of organic carbon are associated with fertile soils with a good structure [11] [12] [7] [13] [14] [15] הגדרה This gives the percentage of organic carbon in the topsoil. Organic Carbon is, together with pH, the best simple indicator of the health status of the soil. Moderate to high amounts of organic carbon are associated with fertile soils with a good structure. Soils that are very poor in organic carbon (<0.2%), invariable need organic or inorganic fertilizer application to be productive. Soils with an organic matter content of less than 0.6% are considered poor in organic matter. The following classes are suggested to prepare maps of organic carbon status for mineral soils Code 1 < 0.2% organic carbon Code 2 = 0.2 – 0.6% organic carbon Code 3 = 0.6 – 1.2% organic carbon Code 4 = 1.2 – 2.0% organic carbon Code 5 > 2.0% organic carbon [7] [9]
קיבולת קטיון Exchange - טיט	38 cmol/kg	האתגרים קרקעות CEC נמוכות נוטות יותר לפתח אשלגן ומגנזיום (וקטיון אחרים) ליקויים, בעוד קרקעות CEC גבוהות הן פחות רגישות לשטיפת הפסדים של קטיונים אלה.. For sandy soils, the addition of a large amount of potassium at one time can lead to high losses due to leaching. This is because the potassium adds a large amount of cations at one time and soil cannot hold on to the excess potassium. Therefore, frequent additions of smaller amounts of potassium can work better to add potassium to the soil than one large amount טיפים הנמוך CEC, pH הקרקע מהר יותר יקטן עם זמן קרקעות חול דורשות לסייד תכוף יותר מאשר קרקעות חימר ועדת הבחירות המרכזית גבוה יותר, ככל שהכמות גדולה של סיד שיש להוסיף כדי להגדיל את ה- pH הקרקע sandy soils need less lime than clay soils to increase soil pH ועדת הבחירות המרכזית גבוה יותר, גדול יותר הכמויות של אדמת תוספות האדמה תצטרך לשנות pH קרקע, או כאשר הגדלת pH בסיד או מים להשקיה גבוה ביקרבונט, או כאשר יורדים pH עם דשני חנקן או גופרית יסודות רקע CEC בטווח של 20 עד 50 cmol / חימר קילוגרם מציין CEC מתון עם קרקעות המכילות מעורב חימר עם הווה kaolinite הנוכחות של כמה kaolinite מצביעה על כך שהקרקע קיימת באקלים טרופי במקצת, שטיפה CEC הוא תלות גבוהה במרקם קרקע ותכולת חומר אורגני בדרך כלל,, גבוה יותר CEC גבוה יותר את התוכן של חימר וחומר אורגני בקרקע CEC של רוב הקרקעות עולה עם עלייה ברמת חומציות קרקע קרקעות מאוד חומצה תהיה ריכוז גבוה של H + וAL3 + בקרקעות בסיסיות בינוני ניטרליות ל, Ca 2 + וMg2 + שולט קרקעות צחיחות מנוקזות עלולות לספוג Na בכמויות גבוהות מאוד רק אחוז קטן של קטיונים המזינים החיוניים לצמחים (K +, Ca 2 +, Mg 2 +, וNH4 +) יהיה "חופשי" בקרקע ובמים ובכך זמין לספיגת צמח, ולכן ועדת הבחירות המרכזית היא חשובה משום שהוא מספק מאגר של חומרים מזינים קטיונים במים בקרקע שדלפו מתחת לrootzone על ידי מים מוחלפים על ידי קטיונים לשעבר קשורים לועדת הבחירות המרכזית "יכולת הצפת 'קיימת עבור חומרים מזינים קטיון כמו גם pH קרקע ריכוזי Lighter להניב צבעים לבנים, צהובים או כתומים בהירים יש kaolinite יכולת לכווץ-להתנפח נמוכה ויכולת החלפת קטיון נמוכה הגדרה This gives the cation exchange capacity of the clay fraction in topsoil. The type of clay mineral dominantly present in the soil is often characterizes a specific set of pedogenetic factors in which the soil has developed. Tropical, leaching climates produce the clay mineral kaolinite, while confined conditions rich in Ca and Mg in climates with a pronounced dry season encourage the formation of the clay mineral smectite (montmorillonite). Nutrient retention capacity is of particular importance for the effectiveness of fertilizer applications and is therefore of special relevance for intermediate and high input level cropping conditions. Nutrient retention capacity refers to the capacity of the soil to retain added nutrients against losses caused by leaching. Plant nutrients are held in the soil on the exchange sites provided by the clay fraction, organic matter and the clay-humus complex. Losses vary with the intensity of leaching which is determined by the rate of drainage of soil moisture through the soil profile. Clay minerals have typical exchange capacities, with kaolinites generally having the lowest at less than 16 cmol/kg, while smectites have one of the highest with a CEC per 100g clay being 80 cmol/kg, or more. The classes generally used in the Harmonized World Soil Database are Class 1 = < 20 cmol/kg clay (kaolinite dominant) Class 2 = 20-50 cmol/kg clay (mixed with kaolinite present) Class 3 = >50-100 cmol/kg clay (mixed, illite) Class 4 = >100 cmol/kg clay (montmorillonite) NOTE: Soils developed on volcanic materials rich in amorphous sesquioxides may have very higher values (over 150 cmol/kg) [7]
קיבולת קטיון Exchange - אדמה	12 cmol/kg	האתגרים העובדה שיש בערכי CEC גדולים היא אינדיקטור שיש אדמת קיבולת גדולה יותר להחזיק קטיונים יש אדמה CEC גבוהה קיבולת גדולה יותר להחזיק קטיונים, כך שיעור גבוה יותר של דשן או סיד לעתים קרובות נדרש לשינוי קרקע CEC גבוה high CEC is an indicator that there is a high reserve of nutrients in the soil Soils with low CEC can take a large amount of fertilizer or lime to correct A high CEC soil requires a higher soil cation level, or soil test, to provide adequate crop nutrition טיפים ועדת הבחירות המרכזית גבוה יותר, ככל שהכמות גדולה של סיד שיש להוסיף כדי להגדיל את ה- pH הקרקע קרקעות חול צריכים פחות סיד מקרקעות חימר כדי להגדיל את ה- pH לרמות רצויים ועדת הבחירות המרכזית גבוה יותר, גדול יותר הכמויות של אדמת תוספות האדמה תצטרך לשנות pH קרקע, או כאשר הגדלת pH בסיד או מים להשקיה גבוה ביקרבונט, או כאשר יורדים pH עם דשני חנקן או גופרית יסודות.. Acceptable saturation ranges for Soil CEC = 6-10: 3-5% K, 50-70% Ca, 8-20% Mg הגדרה This gives the cation exchange capacity in the topsoil. The total nutrient fixing capacity of a soil is well expressed by its Cation Exchange Capacity. Soils with low CEC have little resilience and can not build up stores of nutrients. Many sandy soils have CEC less than 4 cmol/kg. The clay content, the clay type and the organic matter content all determine the total nutrient storage capacity. Nutrient retention capacity is of particular importance for the effectiveness of fertilizer applications and is therefore of special relevance for intermediate and high input level cropping conditions. Nutrient retention capacity refers to the capacity of the soil to retain added nutrients against losses caused by leaching. Plant nutrients are held in the soil on the exchange sites provided by the clay fraction, organic matter and the clay-humus complex. Losses vary with the intensity of leaching which is determined by the rate of drainage of soil moisture through the soil profile. Values in excess of 10 cmol/kg are considered satisfactory for most crops. This is reflected by the following code system used in the Harmonized World Soil Database Code 1 = Cation Exchange Capacity < 4 cmol/kg Code 2 = Cation Exchange Capacity of 4-10 cmol/kg Code 3 = Cation Exchange Capacity > 10 -- 20 cmol/kg Code 4 = Cation Exchange Capacity > 20 -- 40 cmol/kg Code 5 = Cation Exchange Capacity > 40 cmol/kg [7] [9]
טיט - אחוז - משקל	24% משקל	האתגרים שפכים גרועים, יש כמה חללי אוויר, מחממים באיטיות באביב, כבד לטפח תכונות פיזיות שליליות יכולת תפעול עניה דורש יותר מדי ניהול להצלחה בחברות טכנולוגיה מסורתית גידולי עץ לא יכולים לעקור בתשתית Tree roots are damaged as the soil shrinks and swells Low structural stability Very susceptible to water erosion טיפים אל תשתמשו במדרונות מעל 5 אחוזים לחיתוך לעיבוד השתמש בגידולי groundcover על מדרונות פחות מ -5 אחוזים כאשר טראסות, ניקוז משטח שימוש כדי למנוע שפלה הוספת חומר אורגני כדי לשפר את tilth, יכולת התפעול, והניקוז הפנימי אם הניקוז משופר, צמחים יכולים לגדול גם בקרקעות חרסיתית מאז חימר מחזיק יותר חומרים מזינים מאשר רבות קרקעות אחרות Use caution when plowing and tilling Do not plow excessively wet clays, or they will become cloddy Till clay soils only when they are dry and crumble readily In temperate climates, Plow clay soils in the fall, then leave them rough and exposed to the mellowing action of freezing and thawing Frequent, shallow tillage can help to prevent crusting of the topsoil Maize crops require deep cultivation and ridges in the soil to improve drainage (maize cannot tolerate waterlogging and can die if it stands in water for as long as 2 days) Adding lime to clay soils can improve the soil's texture to result in looser and more porous soil השתמש ב- ניקוז להפחית הכובד של הקרקע על ידי הסרת עודפי המים בתקופות יבשות Under-drainage promotes aeration and warmth in clay soils Loosen clay soils by mixing them with humus or sand Barnyard manure or a green manure crop will lighten heavy clay soil To lighten clay soil, spread sand on top of the clay soil and plow it under [16] [17] [18] [19] רקע התחושה של קרקעות חימר היא חלקלקה או גבשושית ודביקה כאשר רטוב מאוד, וקשה ולהחליק כאשר יבש [20] [21] הגדרה This measure the percentage of clay in the topsoil. Clay is naturally occurring firm earthy material, composed primarily of fine-grained (diameter less than 0.002mm) that is plastic when wet and hardens when heated and that consists primarily of hydrated silicates or aluminum. Clay is mostly composed of clay minerals which are phyllo-silicate minerals and minerals which impart plasticity and harden when fired or dried. The definition of "fine grained" used above is particles smaller than 2 µm, colloid chemists (and Eastern European soil scientists) may use 1 µm. The clay content of the soil is listed as a percentage (0 to 100) of the total weight of the soil. Soils is with a high percentage of clay, such as Vertisols, are used for very extensive (grazing, collection of fuelwood, and charcoal burning) through smallholder post-rainy season crop production (millet, sorghum, cotton and chickpeas) to small-scale (rice) and large-scale irrigated agriculture (cotton, wheat, barley, sorghum, chickpeas, flax, noug [Guzotia abessynica] and sugar cane). Cotton is known to perform well on Vertisols, allegedly because cotton has a vertical root system that is not damaged severely by cracking of the soil. Tree crops are generally less successful because tree roots find it difficult to establish themselves in the subsoil and are damaged as the soil shrinks and swells. Management practices for crop production should be directed primarily at water control in combination with conservation or improvement of soil fertility [7]
חצץ - אחוז - נפח	9% משקל	האתגרים חצץ יכול להשפיע על תנאי השתרשות ויכולת תפעול של קרקעות עשוי להיות נמוך בחומר אורגני [7] [22] [23] [24] טיפים להוסיף חומר אורגני לדשן באופן קבוע השתמש חצץ אפונה כקש כדי להגן על השורשים של צמחי מרפא וצמחי הבצורת סובלנית אחרים חצץ אפונה מחזיר את החום ומספק ניקוז טוב [7] [22] [23] [24] הגדרה זה מודד את אחוז הנפח של חצץ בשכבת הקרקע העליונה. חצץ מייצג את אחוז החומרים בקרקע שגודלם עולים על 2 מ"מ. Gravel can affect the rooting conditions and workability of soils. The percentage of gravel in the soil is listed on a scale of 0 to 100 percent volume [18] [25]
חול - אחוז - משקל	47% משקל	האתגרים החול מתייבש במהירות ועשוי להיות חסר חומרים מזינים, כי ניתן לכבס בקלות חומרים מזינים דרך הקרקע עם גשמים או השקיה נמוך בתכולת חומר אורגנית ופוריות יליד נמוך ביכולת לשמור על לחות וחומרים מזינים low in cation exchange and buffer capacities rapidly permeable (i.e., rapid movement of water and air) In the perhumid tropics, sandy soils are chemically exhausted and highly sensitive to erosion טיפים השתמש בהשקיה תכופה, ניקוז מלאכותי, והפריה נכונה (כמויות תכופות יותר אך נמוכות של חומרים מזינים לכל יישום) סה"כ כמויות דשנים ליבול הן בדרך כלל גבוהות למדי Manage erosion and chemical exhaustion in perhumid tropical soils Add organic matter to improve texture, increase water-holding capacity, and improve fertility [26] [19] [20] [27] [28] [29] רקע חול הוא חופשי ניקוז, יש תחושה מחוספסת, מחמם במהירות, והוא קל לטפח תחושה היא גרגירי, לא דביקה [20] הגדרה Sand comprises particles, or granules, ranging in diameter from 0.0625 mm (or 1/16 mm) to 2 millimeters. An individual particle in this range size is termed a sand grain. Sand feels gritty when rubbed between the fingers (silt, by comparison, feels like flour). This measures the percentage (0 to 100) by weight of sand in the topsoil. Sand is commonly divided into five sub-categories based on size very fine sand (1/16 - 1/8 mm diameter) fine sand (1/8 mm - 1/4 mm) medium sand (1/4 mm - 1/2 mm) coarse sand (1/2 mm - 1 mm) and very coarse sand (1 mm - 2 mm) [7] [9]
טין - אחוז - משקל	29% משקל	האתגרים השחיקה [30] טיפים עיבוד קרקע ושליטה שחיקת אמצעים כגון טרסות, שבילים חרושים, חיפוי ושימוש בגידולי כיסוי מסייעים לשמר את הקרקע מדחיסה והידרדרות מבנה רצינית Fertilizers and/or lime are preconditions for continuous cultivation [31] [32] [30] רקע יש קרקעות בוציות מבנה חלש (לשבור בקלות) קל לעבוד התחושה של סחף חלקה וסבון תחושה היא חלק או כמו קמח-כאשר שפשף בין האגודל והאצבעות עושה סרט חלש (ארוך פחות מ -2.5 סנטימטרים) [31] הגדרה Silt is produced by the mechanical weathering of rock, as opposed to the chemical weathering that results in clays. This mechanical weathering can be due to grinding by glaciers, eolian abrasion (sandblasting by the wind) as well as water erosion of rocks on the beds of rivers and streams. Silt is sometimes known as 'rock flour' or 'stone dust', especially when produced by glacial action. Mineralogically, silt is composed mainly of quartz and feldspar. This measures the percentage (0 to 100) by weight of silt in the topsoil. Soils with a lot of silt make excellent farm land, but erode easily. Erosion removes topsoil, reduces levels of soil organic matter, and contributes to the breakdown of soil structure. This creates a less favorable environment for plant growth. Soil erosion can be avoided by: maintaining a protective cover on the soil, creating a barrier to the erosive agent, modifying the landscape to control runoff amounts and rates. Specific practices to avoid water erosion: growing forage crops in rotation or as permanent cover; growing winter cover crops; interseeding; protecting the surface with crop residue; shortening the length and steepness of slopes; increasing water infiltration rates; improving aggregate stability. Specific practices to avoid wind erosion: maintaining a cover of plants or residue, planting shelterbelts, stripcropping, increase surface roughness, cultivating on the contour, maintaining soil aggregates at a size less likely to be carried by wind [7]
מוליכות חשמלית	0.1 dS/m	האתגרים ספיגת עכבות של מים השקיה וwaterlogging יכולים לגרום להמלחת קרקע עודפת [9] [33] טיפים מליחות קרקע שליטה על ידי התרת 10-20% ממי ההשקיה ליץ האדמה, ולאחר מכן להיות מנוקזת ומשוחררת [9] [33] רקע ECE, או מוליכות חשמלית, הוא מדד של מליחות הקרקע [7] הגדרה This gives the electrical conductivity of the topsoil. Coastal and desert soils in particular can be enriched with water-soluble salts or salts more soluble than gypsum. The salt content of a soil can be roughly estimated from the Electrical Conductivity of the soil (EC, expressed in dS/m) measured in a saturated soil paste or a more diluted suspension of soil in water. Accumulation of salts may cause salinity. Excess of free salts referred to as soil salinity is measured as Electric Conductivity (EC in dS/m) or as saturation of the exchange complex with sodium ions. Salinity affects crops through inhibiting the uptake of water. Moderate salinity affects growth and reduces yields; high salinity levels may kill the crop. Crops vary considerably in their resistance and response to salt in soils. Some crops will suffer at values as little as 2 dS/m (spinach) others can stand up to 16 dS/m (date palm). Agronomic relevant limits are Very low ECe < 2 dS/m Low ECe = 2 – 4 dS/m Moderate ECe = 4 – 8 dS/m High ECe = 8 – 16 dS/m Very High ECe > 16 dS/m Some plants are more tolerant to a high salt concentration than others. Highly tolerant plants include date palm, barley, sugarbeet, cotton, asparagus, spinach [7] [9]
גבס תוכן CaSO4	0% נפח	טיפים שימוש בתרבות מים כדי להגדיל את הריכוז של תערובת SO4 (K2SO4 + MgSO4) מגביר את הספיגה של NO3, K, Mg וגופרית אבל מקטין את הספיגה של Ca וP השתמש בטראסות אדמה כדי למנוע סחף Use supplementary irrigation to increase productivity where water resources are available Harrow the land after harvesting and before the rainy season to improve the infiltration of water and conserve soil moisture Increase organic matter by replacing fallow by small-grain leguminous crops in the wheat-fallow rotations Add manure Use subsoiling to break the cemented gypsic subsoil to improve root penetration and reduces susceptibility to drought, especially in the case of fruit and forest trees Do not mix the topsoil and subsoil Apply nitrogen and phosphorus to cereals N is generally applied where rainfall exceeds 260 mm annually Phosphorus fertilizers increase the yield of cereals, especially under low rainfall For irrigated gypsiferous soils: The use of (NH4)2CO3 solution was found to cause the optimum elimination of gypsum in gypsiferous soils with both low and high levels of gypsum; In general, there is need for ample nitrogen fertilizers for crops grown on gypsiferous soils, especially under irrigated agriculture. There are no significant differences between the requirements of crops for nitrogen on gypsiferous and non-gypsiferous soils; Molybdenum applications might benefit many plants, especially legumes [34] [7] רקע עד 2 גבס אחוזים בקרקע מעדיף גידול צמחים רוב הגידולים החקלאיים בקרקעות לשגשג ללא לתוכן גבס נמוך מאוד הגדרה Calcium sulphate (gypsum) content in topsoil. Gypsum is a chemical compound (a salt) which occurs occasionally in soils particularly in the driest areas of the globe where it can occur in a flower-like form typically opaque with embedded sand grains called desert rose. In soils it may occur in fibers, crystals or soft. Research indicates that up to 2 percent gypsum in the soil favours plant growth, between 2 and 25 percent has little or no adverse effect if in powdery form, but more than 25 percent can cause substantial reduction in yields. It is suggested that reductions are due in part to imbalanced ion ratios, particularly K:Ca and Mg:Ca. Gypsum strongly limits available soil moisture. Tolerance of crops to gypsum varies widely (FAO, 1990; Sys, 1993). Relevant limits are considered the following None to very low CaSO4 < 2% Low CaSO4 = 2 – 5% Moderate CaSO4 = 5 – 25% High CaSO4 = 25 – 40% Very High CaSO4 > 40%
Soil reaction - ה-pH	6.4 -log H+	האתגרים כבול עם pH של 3.0 יכול להיות מומלץ כתוסף קרקע, אבל כבול הוא דל בחומרי הזנה, יקר, וזה משאב בלתי מתחדש [35] [36] [37] [38] [39] טיפים טווח pH האידיאלי עבור מרבית הגידולים הוא 6.5-7.0, לכן חלק גידולים עשויים לדרוש התאמת pH קלה לצמיחה אופטימלית כדי להוריד את רמת חומציות קרקע, להוסיף מקור של חומצה, כגון עלים גרוסים, גופרית, נסורת או כבול הוסף חומר בסיסי כגון גיר כדי להקטין את חומציות קרקע החל 2.3 קילוגרם של סיד לכל 30 מ"ר להעלות את ה- pH בנקודה אחת Applying wood ashes will raise soil pH--Wood ashes contain up to 70 percent calcium carbonate, as well as potassium, phosphorus, and many trace elements. Because it is powdery, wood ash is a fast-acting liming material Limit the application of wood ashes to 1 kg per 30 square meters and only apply it every other year in the same area Breed aluminum-tolerant crops [35] [36] [37] [38] רקע מיני צמחים רבים מותאמים לקרקעות חומציות או בסיסיות The availability of many plant nutrients (for example, P), non-essential elements (for example, Al, Cd, Pb), and essential trace elements (for example, Mn, Fe, Cu, Zn) is strongly dependent on soil pH (Miller and Gardiner 2001) Generally, metal cations (for example, Mn, Fe, Ni, Cu, Zn, Cd, Pb) become more available as pH decreases, while oxyanions (for example, SO4) become more available at alkaline pH levels Soil pH is strongly dependent on the chemical weathering environment. Soils in hot, humid areas and even mesic, wetter areas tend to be more acidic than those of much drier areas. Vegetation communities in those areas tend to be adapted to the soil conditions in which they developed [7] [40] [41] הגדרה זה נותן את תגובת האדמה של תשתית. pH, נמדד בתמיסת קרקע-מים, הנו מדד לחומציות והבסיסית של האדמה. חמש כיתות pH גדולות נחשבות כאן שיש להם משמעויות ספציפיות אגרונומיות pH < 4.5 = Extremely acid soils include Acid Sulfate Soils (Mangrove soils, cat clays). Do not drain because by oxidation sulfuric acid will be produced and pH will drop lower still pH 4.5 – 5.5 = Very acid soils suffering often from Al toxicity. Some crops are tolerant for these conditions (Tea, Pineapple) pH 5.5 –7.2 = Acid to neutral soils - these are the best pH conditions for nutrient availability and suitable for most crops pH 7.2 – 8.5 = These pH values are indicative of carbonate rich soils. Depending on the form and concentration of calcium carbonate they may result in well structured soils which may however have depth limitations when the calcium carbonate hardens in an impermeable layer and chemically forms less available carbonates affecting nutrient availability (Phosphorus, Iron) pH > 8.5 = Indicates alkaline soils often highly sodic (Na reaching toxic levels), badly structured (columnar structure) and easily dispersed surface clays [7] [42]
להחלפה נתרן	1%	הגדרה This gives the exchangeable sodium percentage in the topsoil. The exchangeable sodium percentage has been used to indicate levels of sodium in soils it is calculated as the ratio of Na in the CEC (or sum of cations) ESP= Na*100/CECsoil. Alternatively SAR (Sodium Adsorption Ratio) has been used (SAR= Na/Square root ((Ca+Mg)/2)) to indicate levels of sodium hazards for crops. Excess of free salts referred to as saturation of the exchange complex with sodium ions, which is referred to as sodicity or sodium alkalinity and is measured as Exchangeable Sodium Percentage (ESP). Sodicity causes sodium toxicity and affects soil structure leading to massive or coarse columnar structure with low permeability. Sodic soils have a low infiltration rate, they are poorly aerated and difficult to cultivate. Thus, sodic soils adversely affect the plants' growth. Agronomic relevant limits are Low ESP < 6% Moderate ESP = 6 – 15% High ESP = 15 – 25% Very High ESP > 25% [7] [9]
עיקר ההתייחסות צפיפות	1.54 kg/dm3	טיפים To reduce high bulk density and compaction, minimize soil disturbance and production activities when soils are wet, use designated field roads or rows for equipment traffic, reduce the number of trips across the area, and maintain or increase soil organic matter Use grazing systems that minimize livestock traffic and loafing, provide protected heavy use areas, and adhere to recommended minimum grazing heights Use conservation crop rotation, cover crop, deep tillage, prescribed grazing residue, and tillage management Avoid plowing, timber harvesting, or compaction of the soil [43] [13] [14] [15] רקע צפיפות בצובר אדמה עשויה להצביע על הידוק קרקע אך תלויה בגורמים רבים, כולל קרקע הפצת חלקיקים בגודל, תוכן חומר אורגני בקרקע, ותוכן שבר גס צפיפות בצובר גדלה ככל שגדל תוכן החול וסלעים Bulk density decreases as the organic matter content increases A mineral soil with “ideal” physical properties has 50 percent solids and 50 percent pore space occupying a given volume of space At optimal water content, half the pore space is filled with water (such a soil will have a bulk density of 1.33 g/cm3) Roots usually grow well in soils with bulk densities of up to 1.4 g/cm3 Root penetration begins to decline significantly at bulk densities above 1.7 g/cm3 Above 1.5 g/cm3, there is an increasing probability of adverse effects from soil compaction or high rock content Coarse fragments—Soils with a coarse fragment content of > 50 percent to have a greater probability of adverse effects from infiltration rates that are too high, water storage capacity that is too low, more difficult root penetration, and greater difficulty in seed germination and seedling growth A high contents of coarse fragments can limit soil productivity [43] [13] [14] [15] הגדרה Reference bulk density is a property of particulate materials. It is the mass of many particles of the material divided by the volume they occupy. The volume includes the space between particles as well as the space inside the pores of individual particles. This is a measurement in kg/dm3 of the topsoil reference bulk density. Bulk density reflects the soil’s ability to function for structural support, water and solute movement, and soil aeration. High bulk density is an indicator of low soil porosity and soil compaction. It may cause restrictions to root growth, and poor movement of air and water through the soil. Compaction can result in shallow plant rooting and poor plant growth, influencing crop yield and reducing vegetative cover available to protect soil from erosion. By reducing water infiltration into the soil, compaction can lead to increased runoff and erosion from sloping land or waterlogged soils in flatter areas. In general, some soil compaction to restrict water movement through the soil profile is beneficial under arid conditions, but under humid conditions compaction decreases yields. On cropland, long-term solutions to bulk density and soil compaction problems revolve around decreasing soil disturbance and increasing soil organic matter. A system that uses cover crops, crop residues, perennial sod, and/or reduced tillage results in increased soil organic matter, less disturbance and reduced bulk density. Additionally, the use of multi-crop systems involving plants with different rooting depths can help break up compacted soil layers [7] [32] [44]
חנקן (N)		האתגרים יותר מדי חנקן באדמה יכול לפגוע בצמחים חנקן הוספה קל, אבל הסרת עודף חנקן בקרקע קשה יותר יותר מדי חנקן בקרקע מפחית את היכולת של צמחים לפירות ופרחים [45] [13] [14] [46] טיפים Organic methods of adding nitrogen to the soil include: adding composted manure to the soil, planting a green manure crop such as borage, planting nitrogen-fixing plants such as peas or beans, and adding coffee grounds to the soil, but be careful when adding coffee grounds as this practice also creates acidity and lowers pH of the soil. Organic methods require more time than inorganic methods, but they can result in a more even distribution of the added nitrogen. Non-organic methods of adding nitrogen to the soil include the use of chemical fertilizers. A high-nitrogen fertilizer will have a high first number in the NPK ratio, for example 10-10-10. Nitrogen-containing chemical fertilizers act quickly to add nitrogen to the soil, but the nitrogen also leaves the soil quickly. If there is too much nitrogen in the soil, plant squash, cabbage, broccoli or maize which will use up large amounts of nitrogen while they grow. Note: while these plants absorb the excess nitrogen in the soil, they may look unhealthy and may produce low yields [45] [13] [14] [46] רקע חנקן כללי בקרקעות מינרלים (באחוזים):> 0.5 = גבוהה - קרן מצוינת של חנקן 0.1-0.5 = מתונות - רמות מספיקות <0.1 = נמוך - יכולים להצביע על אובדן של נ 'האורגני Nitrogen is essential for plant growth. Plants will not grow or produce without sufficient nitrogen When legumes and other nitrogen fixing plants and the bacteria called Rhizobium work together to store the nitrogen, they are creating a green warehouse in the soil. While they are growing, they release very little nitrogen into the soil, but when they are done growing and they die, their decomposition release the stored nitrogen and increases the total nitrogen in soil. Their death makes nitrogen for plants available later on. When the plant stores the nitrogen in the roots, it produces a lump on the root called a nitrogen nodule. This is harmless to the plant but very beneficial to the farm [45] [13] [14] [46]
זרחן (P)		האתגרים בדרך כלל, זה קשה לצמחים לספוג זרחן (P), כך זה בדרך כלל לא חשש שצמחים יספגו יותר מדי פ: צמחים הגדלים על קרקעות עם רמות P אולסן-חילוץ מעל 10 מ"ג / קילוגרם בדרך כלל לא יגיבו לפ הוסיף Do not overuse P: soils with very high levels of extractable P may have a deleterious effect on water quality if such soils are subjected to erosion and the soil particles end up in receiving waters [47] [13] [14] [46] טיפים עבור משק אורגני, משתמש בדשנים המכיל פוספט, כגון NPK עם ערך גבוה P (הערך באמצע) Use bone meal or rock phosphate to correct a phosphorus deficiency Add compost to the soil to help plants take up the phosphorus that is already in the soil [47] [13] [14] [46] רקע זרחן הוא אחד החומרים המזינים החיוניים הנדרשים לגידול צמחים ופיתוח. זה עוזר צמחים להמיר חומרים מזינים אחרים על מנת שהצמח לגדול Phosphorus is the "P" component of N-P-K fertilizers. The availability of soil P to plants depends on the forms of P in soils and soil pH In acid soils, most plant-available P is associated with Fe and Al oxides and is best extracted with the Bray 1 extractant (0.03 M NH4F + 0.025 M HCl). The Bray 1 extractant is applicable to soils with a pH below 6.8, but not to near-neutral or alkaline soils because the acid in the extract begins to dissolve Ca phosphates. These Ca phosphates usually release only small amounts of P for plant uptake unless they begin to dissolve under more acid conditions. Generally, deficiency symptoms are not exhibited by plants growing in soils with Bray 1 levels above 15 mg/kg (Soil and Plant Analysis Council 1999) In alkaline soils, most soil P is associated with Ca, either sorbed to carbonate minerals or existing as various Ca phosphate minerals, the most common of which is apatite. The Olsen (pH 8.5, 0.5 M NaHCO3) extractant was developed to measure plant-available P in alkaline soils, but it also works in many acid soils. The bicarbonate ions release P sorbed to many mineral surfaces that is plant available without dissolving the otherwise plant-unavailable P in Ca phosphates [47] [13] [14] [46]
אשלגן (K)		טיפים לפעמים דשן אשלגן נקרא דשן האשלג דשן אשלגן גבוה מכיל אשלגן בלבד (K) או יש לו ערך K גבוה Compost made primarily from food byproducts, especially banana peels, is an excellent source of potassium for the soil when used as a soil additive Use wood ash as a light application to avoid burning plants Greensand can be used as a soil additive to add potassium to the soil Because potassium deficiency in plants is difficult to diagnose visually, test the soil before adding more potassium [48] [13] [14] [46] רקע עם כל הצמחים, אשלגן מסייע את כל הפונקציות בתוך המפעל. כאשר צמח יש מספיק אשלגן, זה יהיה פשוט להיות מפעל כולל טוב יותר Potassium is important to plant growth and development. Potassium helps: plants grow faster, use water better and be more drought resistant, fight off disease, resist pests, grow stronger, and produce more crops K (mg/kg): > 500 = High – excellent reserve 100 to 500 = Moderate – adequate levels for most plants < 100 = Low – possible deficiencies [48] [13] [14] [46]

Zero Tillage

Conservation tillage systems such as zero tillage cause minimum disturbance to the soil after the previous crop has been harvested. In zero tillage, the ideal is to plant direct into the soil, without hoeing or plowing. Tillage is reduced to ripping planting lines or making holes for planting with a hoe. Crop residues are left in the field to reduce soil erosion, conserve moisture, inhibit weed growth, and act as green manure. Zero tillage is not recommended when disease is present. To manage disease, crop residues must be either removed from the field and destroyed or deeply ploughed to reduce sources of disease infection and spread.

Advantages of conservation tillage include less machinery, labour and fuel, as well as reduced soil erosion and compaction. Disadvantages of conservation tillage include lower soil temperatures, slower germination and emergence when direct sowing is used, slower early growth, delayed competition with weeds, higher incidence of root diseases, heavier crop residue, the possibility of more difficult planter operation, weed spectrum changes, and potential increase of soil insect pests or insects that spend part of their life cycle in the soil (e.g. cutworms, thrips, leafmining flies, grubs). Cultivation exposes these pests to desiccation by the sun heat and to predation by natural enemies.

Green Manuring

Green manure legumes create nitrogen in the soil by fixing it from the atmosphere.

Benefits of Green Manure Cover Crops

Easy to grow
Increases soil organic matter
Reduce soil losses from wind and water erosion
If it is a legume, it can fix nitrogen. When the legume is mature, chopped up and added to the soil, it will add nitrogen to the soil which will be used by later crops on the land.
The roots of the green manure crops extract nutrients from deep in the soil.
The deep roots work to break up and aerate the soil
When the green manure is added to the soil, it works to lighten and loosen the soil to aerate and improve drainage, making the soil healthier for later crops. After tilling in a green manure crop, we see the soil level in the farm beds raise several inches. The soil is loose and no longer compacted.
Green manure crops include jack beans, perennial peanut, and Mucuna.
These plants help the main crop by increasing soil fertility by adding nitrogen to the soil by nitrogen fixation.
They add biomass (organic matter) to the soil.
As cover crops, they reduce soil loss.

Planting Green Manure Crops

Green manure crops can be planting using intercropping with the main crop or by using crop rotation in which the green manure crop is planted in-between plantings of the main crop. For intercropping, plant the legume seeds in rows between rows of the main crop. Plow the legumes into the soil at the start of the rainy season.

In crop rotation, plant legumes after the main crop has been harvested. The legumes will benefit the field as a cover crop and as green manure. At full biomass maturity, plow the legumes into the soil as green manure for the next crop.

For a source of green manure to the field, cut the legumes at full maturity, shred, and spread over the field.

Preventing Soil Erosion while Adding Nutrients to the Soil

The first step in soil management is preventing the loss, or erosion, of soil. Topsoil is particularly vulnerable to erosion if not protected by plants or mulch or by other measures. The soil that remains after the loss of topsoil is usually less productive, which can result in lower yields. The challenge is to protect soil while using the land for food production and other non-food activities.

Soil erosion is caused mainly by wind and water but also by incorrect cultivation practices. Rain and wind dislodge and then carry away soil particles. Where the soil is bare or the vegetation poor, rainwater does not seep into the soil; instead it runs off and carries with it loose topsoil. Sloping land and light soils with low organic matter content are both prone to erosion. Once eroded, the soil is lost forever.

Soil erosion is a problem in regions with little vegetation, particularly in the semi-arid and arid zones. In the humid tropics, erosion was not considered a problem when the land was in its natural state, because the variety of native plants kept the soils covered at all times. Now, people are clearing more land for agricultural purposes, and the situation has changed. Heavy rains coupled with poor soil management of cultivated areas are now common causes of soil erosion in the humid areas.

Water Erosion

Some common forms of water erosion include:

Sheet erosion: a thin top layer of soil is removed from the soil by the impact of rain. With sheet erosion, small heaps of loose material (e.g. grass) amass between fine lines of sand after a rainstorm. This erosion takes place across a whole garden or field.
Rill erosion: water flows over minor depressions on the land's surface and cuts small channels into the soil. The erosion takes place along the length of these channels.
Gully erosion: a gully forms along natural depressions on the soil's surface or on slopes. The head of a gully moves up the slope in the opposite direction of the flow of water. Gullies are symptoms of severe erosion.

Wind Erosion

This occurs mostly on light soils and bare land. High winds cause severe damage. Wind erosion is a common problem in dry and semi-arid areas, as well as in areas that get seasonal rains.

Unlike water which only erodes on slopes, wind can remove soil from flat land as well as from sloping land; it can also transport the soil particles through the air and deposit them far away. Soils vulnerable to wind erosion are dry, loose, light soils with little or no vegetative cover.

Plowing up and down a slope causes soil erosion. To prevent the loss of soils, certain measures must be taken.

These include:

clearing only the land to be cultivated;
planting along a contour and using grassed channels;
establishing windbreaks and bench terraces;
plowing along a contour;
planting cover crops and mulching.

When clearing land for cultivation, the beneficial effects of certain trees and plants should be considered. Some trees should be left, since they may supply food, medicine, shade or, when they shed their leaves, organic matter.

Feeding the Soil

One of the main goals in growing crops is to make the soil fertile and well structured, so a wide range of useful crops can grow and produce well. In order to grow, plants require nutrients that are present in organic matter, such as nitrogen, calcium and phosphorus, as well as minerals and trace elements.

If the natural fertility or structure of the soil is poor, it must be continuously "fed" with organic matter, such as leaves and manure, in order to improve its productivity and water-holding capacity. As organic matter decomposes, it becomes food for plants. It also improves soil structure by loosening heavy clay and binding sandy soil.

Feeding the soil with organic matter is especially important in the early years of cultivating the land. Organic matter (i.e. waste from plants and livestock) can be collected and buried in the soil, where it will decompose. The organic matter also can be used to make compost, which can be applied to the soil to enrich its fertility.

The roots of legumes contain nitrogen-fixing bacteria. Therefore, intercropping or rotating legumes with other crops helps maintain or improve the nitrogen content of the soil, and this enhances the growth of other plants.

Healthy plants yield more and are better protected from insects and disease. The application of organic matter, such as compost, animal manure, green manure and soil from anthills, improves soil structure and adds nutrients to the soil.

Long-Term Soil Management

The ideal way to protect and feed the soil is to apply organic matter or compost regularly and to keep the soil covered with plants. A multilayer cropping system in which a mixture of trees and other plants with different maturity times are grown together will protect the soil and recycle nutrients. Leguminous plants such as cowpeas, groundnuts and beans are particularly useful in providing continuous nutrients for crops.

Apply Organic Matter to Soil to Improve the Crop

Plants can contain up to 90 percent water. The water is absorbed mainly through the root system of the plant. With the water, plant nutrients are absorbed. Healthy roots need air (aeration) for development. Excess water in the soil prevents air from penetrating and damages a plant's roots. Water management is therefore extremely important in regions with good water resources as well as in those where water is scarce.

The water-holding capacity of soil varies according to soil type. Soil with a high content of organic matter has better aeration, better structure and better water-holding capacity. Heavy, sticky soils are too dense to allow air in and water out, so roots cannot breathe and plants can have growth problems. When this kind of soil dries out, it sets like cement, and water takes a long time to soak into it. On the other hand, sandy, coarse-grained soils are too loose to hold water before it drains away. In this kind of soil, without a regular external water supply, a plant's roots cannot find enough water for growth. Regular application of organic matter will improve the ability of both these kinds of soil to hold and release enough water and air. During land preparation for planting, organic materials such as animal manure or compost should be applied to the land such that they are well incorporated into the soil.

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32. Discovery Education (http://school.discoveryeducation.com/schooladventures/soil/name_soil.html)
33. Wikipedia.org, "Soil Salinity Control" (http://en.wikipedia.org/wiki/Soil_salinity_control), last modified on January 19, 2012.
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36. PlanTea (http://www.plantea.com/pH.htm)
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39. Spectrum Analytic (http://www.spectrumanalytic.com/support/library/ff/CEC_BpH_and_percent_sat.htm)
40. Pennsylvania State University (http://pubs.cas.psu.edu/FreePubs/pdfs/uc038.pdf)
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46. Perry, Charles H. 2007. Soil vital signs: A new Soil Quality Index (SQI) for assessing forest soil health. Res. Pap. RMRS-RP-65WWW. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 12 p. (http://www.fs.fed.us/rm/pubs/rmrs_rp065.pdf).
47. Rhoades, Heather, "The Importance Of Phosphorus In Plant Growth," Gardening Know How (http://www.gardeningknowhow.com/gardening-how-to/phosphorus-plant-growth.htm)
48. Rhoades, Heather, "Plants And Potassium: Using Potassium And Potassium Deficiency In Plants," Gardening Know How (http://www.gardeningknowhow.com/gardening-how-to/plants-potassium.htm)

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