File Name: soil fertility and fertilizers .zip
Food insecurity is a central concern and a fundamental challenge for human welfare and economic growth in Africa. Low agricultural production, results in low incomes, poor nutrition, vulnerability to risks and lack of empowerment. Land degradation and soil fertility depletion are considered the major threats to food security and natural resource conservation in sub-Saharan Africa SSA.
Analyzed the data: WD XZ. Appropriate fertilizer application is an important management practice to improve soil fertility and quality in the red soil regions of China. Results showed that the soil pH was the lowest with an average of 5.
Enter your mobile number or email address below and we'll send you a link to download the free Kindle App. Then you can start reading Kindle books on your smartphone, tablet, or computer - no Kindle device required. Soil Fertility and Fertilizers: An Introduction to Nutrient Management, Eighth Edition, provides a thorough understanding of the biological, chemical, and physical properties affecting soil fertility and plant nutrition. Covering all aspects of nutrient management for profitable crop production, the text pays particular attention to minimizing the environmental impact of soil and fertilizer management.
Soil Fertility and Fertilizers, 8th Edition
See the Latest Publications. Browse All Publications. Download PDF. Corn has been a crop in North Dakota for at least years. However, the acres under corn grain production have been relatively small, compared with small-grain crops, until about 20 years ago.
Today, corn acres are consistently above 3 million acres each year, with most North Dakota counties having significant acreage. The surge in acreage has been the result of improved corn genetics supported by NDSU corn inbred research, combined with greater rainfall and the increase of long-term no-till acreage in western North Dakota.
Fertilizer recommendations for corn used until recently were published about 40 years ago and have been changed little since then. However, in the past 40 years, yield expectations have at least doubled from about 80 bushels per acre to more than bushels per acre in many fields. Tillage practices and the hybrids planted have changed as well. The changes from previous corn fertility recommendations in this publication are primarily the result of recent assessments of corn yield responses to nitrogen N and potassium K through field experiments using modern hybrids and conditions.
The nitrogen N recommendations in this publication were developed from data accumulated from through on 77 North Dakota corn N rate trials. In addition, data from recent N rate studies in northwestern Minnesota, southern Manitoba and the northern tier of counties in South Dakota were used to augment the NDSU dataset.
A fall soil test to 2 feet in depth is a very important component of the N recommendation. Figure 1 illustrates the poor predictive relationship between N applied and yield when the soil test nitrate-N results are not included in the analysis.
Figure 1. All data from North Dakota, Minnesota, Manitoba and South Dakota relating corn yield to N rate only top or N rate with soil nitrate analysis to 2 feet in depth below. A change from previous recommendations is that N recommendations are not linked directly to expected yield. N recommendation categories within high-clay soils and medium-texture soils are divided into those soils with a historic capability to produce more or less than bushels per acre.
However, within the higher-productivity categories, N rates have supported more than bushels per acre in my experiments. Yields less than this were caused by too much water or not enough, but not by a deficiency of N.
Nitrogen recommendations are based on an economic production function that takes into account the yield response of corn to added N, less the cost of the N. In our work, we determined the formula that related the total available N to yield for each recommendation category.
As available N increases, yield increases until the cost of another pound of N equals the income benefit for the fraction of a bushel of corn the N will produce. At some rate of N, yield can decrease with added N. The response of corn to N is different between west-river soils and soils east of the Missouri River. Part of this difference may be due to the tendency for productive corn acres west of the Missouri River to be in long-term no-till, but some is due to the soils and generally warmer and drier climate of the west-river region Table 1.
In eastern North Dakota, long-term no-till, defined as continuous no-till six years or longer, is segregated from conventional-tillage sites Table 2. This phenomenon also was seen in North Dakota spring wheat and durum research between and , where a pound-per-acre N credit was recommended in fields in long-term no-till. In the corn N rate studies, the difference in N recommendation between long-term no-till and conventional-till soils was between 40 and 50 pounds less N per acre for long-term no-till soils.
However, rather than incorporate a credit, a separate return to N analysis was prepared. Within the conventional-till soils in eastern North Dakota, soils are divided into high-clay and medium textures. High clays include the textures of clay, clay loam and silty clay loam. Bearden, Fargo, Hegne and Viking soils are some of many soils in eastern North Dakota that would fall into this category.
These soils have a high susceptibility for denitrification, which is a soil bacteria-led process in which nitrate is converted to nitrous oxide and nitrogen gas and is lost from the soil into the atmosphere.
Denitrification proceeds when soil pores are filled with water and soil oxygen levels are low. Denitrification can be found anytime that the soil is flooded, but in high-clay soils, significant denitrification occurs, even when the soil is muddy or saturated but not flooded.
Tiling or no tiling made little difference in our N rate plots on N efficiency in high-clay soils. Water takes a long time to percolate through high-clay soils. Some estimates of downward water movement are 0. High-clay soils are divided into those with historic yields exceeding bushels per acre and those with historic yields of less than bushels per acre. In the higher-productivity, high-clay soils, side-dress N is encouraged due to denitrification susceptibility; however, these soils have better internal drainage than those with lower yield capability, and growers might be able to achieve maximum economic yield with a greater portion of their total N applied preplant Table 3.
The high-clay soils with lower productivity Table 4 are likely to benefit from a side-dress N application. The N rate from the recommendation table at a certain N cost and corn price is the maximum to apply preplant to these soils. To apply enough preplant N to these soils to support yields similar to those soils with higher historic yields would result in impractical N rates of more than pounds per acre. The answer to higher yield in these soils is not rate, but timing. Application of half or more of the recommended N at V6 to V8 would increase yield and N efficiency greatly in wetter years.
Considering the tendency for high-clay soil to have sticky, mucky characteristics in wet conditions, the use of a coulter UAN solution of urea and ammonium nitrate in water side-dress applicator is recommended.
Medium-textured soils would include fine sandy loams, silt loams, loams, sandy loams, loamy sands and sands. The medium-textured soils with historic yield greater than bushels per acre Table 5 were the most productive and N-efficient soils in the conventional tillage category.
These soils do not require N to be side-dressed to be N efficient. However, the medium-textured soils with less than bushels per acre were the most N-inefficient soils in our studies Table 6. These soils are highly susceptibility to leaching and would benefit greatly from side-dressing part of the N. Soils in this category usually are side-dressed using an anhydrous ammonia applicator, although a coulter UAN side-dress applicator also would work well. For any subsurface-applied side-dress applicator, application may be made in every other row, rather than every row.
An alternative side-dress application would be UAN streamed between each row. The efficiency of this alternative is high except in drier years, where surface dryness leads to greater N inefficiency. A more risky application method would be to apply up to pounds of urea 46 pounds of N per acre broadcast over the whorl using a granular ground applicator or by air. The N recommendations for irrigated corn are included in Table 7.
These are the total N rates recommended through a Return to N model based on data collected in the Oakes area by Knighton, Derby and Albus in the s. The total N recommended should be divided into preplant, side-dress and the remaining N, which should be provided through the irrigation pivot up to tassel initiation.
An additional 20 to 30 pounds of N could be applied if yield conditions are exceptional after pollination. No N is recommended through the pivot during pollination. In states to the south and east of North Dakota, distinctions are made within states where banded phosphorus P would be expected to have a consistent positive yield response and areas where it might not.
These distinctions are usually a point north or south of some line within the state. In North Dakota, we are north of all of these lines; so in North Dakota, every corn acre would benefit in most years from an in-furrow or side-band P application.
An example of the dramatic difference possible through banding P in some North Dakota soils is provided in Table 8 from the Carrington Research and Extension Center. The in-furrow band, as seen in Table 8 , is effective at placing fertilizer near the initial small rootlets. However, placing fertilizer in the 2 by 2 band eliminates the risk of seed damage from salt or ammonium concentration near the seed, which always results in lower stand with an in-furrow fertilizer placement. The configuration of a 2 by 2 band in modern planters is not easy, but many growers use this configuration and they are able to apply N, P, potassium K , sulfur S and zinc Zn easily with their starter with no reduction in stand.
In a 2 by 2 starter band, the N rate should be 50 pounds per acre or less to achieve a starter effect with any P in the band. Nitrogen rates higher than 50 pounds per acre in the starter band produce levels of free ammonia that are not penetrated by roots until later in the season, when the time for helpful early season effects of concentrated P are past. Most of the P applied to corn is applied as broadcast P. Starter P sometimes can produce most of the yield benefit from a P application; however, corn grain contains about 0.
The P soil test used in the state should be the Olsen sodium bicarbonate extractant because it is diagnostic of relative soil P availability in acidic and basic soils.
In one fertilization strategy utilized by most of the central U. Corn Belt states, buildup and maintenance, P anticipated to be removed is applied maintenance along with enough P to increase soil test levels through time buildup.
A typical P application in Illinois, for example, that is necessary to increase soil test levels is about 9 pounds of P2O5 to increase the soil test 1 pound in the Bray P1 test. Experiments in Minnesota have indicated a range of P2O5 rates from 9 pounds to more than 40 pounds to achieve a similar soil test increase. Most inorganic soil P is held by some soil mineral.
No P fertilizer amendment effectively reduces the binding of P to soil minerals. In acid soils from below pH 5 to 6. In alkaline soils with a pH above 7, the dominant P-binding ion is calcium. In some of my experiments, yields approaching bushels per acre were achieved in soils with P levels in the low range less than 8 parts per million [ppm].
The corn obviously was taking up large quantities of P, even in soil test levels that were not optimum. Some of the soil P available to crops is in organic form, which neither the Olsen nor the Bray test is very good at estimating. Recent studies in Minnesota have indicated that the current critical level for P should be closer to 20 ppm Olsen rather than 15 ppm.
North Dakota corn growers with very high yield potential might strive to achieve this higher soil test level if soil conservation methods and terrain were consistent with low wind and water erosion from their fields.
General P recommendations for corn can be found in Table to Many state best management practices to reduce P pollution of surface waters are based on soil P particulate movement.
However, studies in Manitoba indicate that the greatest source of P in surface water bodies in our relatively flat-terrain region is not from particulates but from soluble P in residues and other rotting organic sources, mostly released in early spring.
Mycorrhizae are a group of soil fungi that have a symbiotic relationship with many plant families, except for the Chenopodiaceae lambsquarter family and the Cruciferae mustard family.
When corn follows canola mustard family or sugar beet lambsquarter family , the likely result is fallow syndrome. Prevent plant acres generally have not resulted in fallow syndrome the following year, probably because in most cases, these acres are seeded to a cover crop highly recommended or weeds grow for a significant portion of the summer, which also promotes mycchorizal populations.
Work in South Dakota indicates that high rates of P fertilizer banded near the seed are necessary to offset the effects of fallow syndrome. A minimum P fertilizer rate in one study was pounds per acre in a 2 by 2 band. Simply increasing an in-furrow rate from 3 gallons per acre to 6 gallons per acre does not eliminate fallow syndrome. Soil test potassium K values have been high for most soils in North Dakota until recently.
With greater K removal with soybean and corn grain, soil test K levels have decreased in eastern North Dakota.
Metrics details. Land degradation reduces agricultural productivity and poses a serious threat on food security status of households. Several reports that indicate lack of response to these fertilizers, which could be due to limitation of nutrients other than nitrogen and phosphorus. Therefore, the present study was initiated to evaluate the soil fertility status of ten sites in central highlands Vertisols of Ethiopia and wheat nutrient content. The physico-chemical properties of soils showed that the soils were clayey in texture, neutral to slightly alkaline pH 7. Exchangeable K, Ca and Mg in all soil samples were high, while available sulfur was low.
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Appropriate fertilizer application is an important management practice to improve soil fertility and quality in the red soil regions of China. Results showed that the soil pH was the lowest with an average of 5. Thus, these indicated that organic manure should be recommended to improve soil fertility in this region and K fertilizer should be simultaneously applied considering the soil K contents. Considering the long-term fertilizer efficiency, our results also suggest that annual straw returning application could improve soil fertility in this trial region. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Most of the time, the average person treats the soil "like dirt". In the plant-animal-soil continuum, soil is often neglected because it does not indicate stress in an obvious way. Animals and plants show physical symptoms but the soil must be looked at more carefully to monitor good health.
Люди на подиуме с недоумением переглянулись. Дэвид подмигнул крошечной Сьюзан на своем мониторе. - Шестьдесят четыре буквы.
Она там, потому что я ее туда запустил. Сквозь строй не позволял мне загрузить этот файл, поэтому я обошел фильтры. - Глаза коммандера, сузившись, пристально смотрели на Чатрукьяна. - Ну, что еще - до того как вы отправитесь домой.
Это было радостное избавление от вечного напряжения, связанного с ее служебным положением в АНБ. В один из прохладных осенних дней они сидели на стадионе, наблюдая за тем, как футбольная команда Рутгерса громит команду Джорджтауне кого университета. - Я забыла: как называется вид спорта, которым ты увлекаешься? - спросила Сьюзан.
Чутье подсказывает мне, что здесь все верно. Бринкерхофф нахмурился. Даже директор не ставил под сомнение чутье Мидж Милкен - у нее была странная особенность всегда оказываться правой. - Что-то затевается, - заявила Мидж.