摘要:

The size of farms in the USA has steadily increased in recent decades. Farm size is part of the controversy about sustainable agriculture. The methodology for managing large‐scale farms is not all conducive to the procedures which can give more sustainability.

ISSN:0010-3624    

DOI:10.1080/00103629409369006

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Most of the food in the world is produced by a billion farmers who each tend an average of about one hectare of land. Modern technology is forcing the average size of farms to increase, but most sustainability and productivity per unit of land come with the small sizes. Several factors contribute to the environmental advantages associated with small‐scale agriculture. If ignorance and poverty can be eliminated, small‐scale farms would result in the most productive and sustainable systems with other advantages.

ISSN:0010-3624    

DOI:10.1080/00103629409369007

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Ignorance and poverty are barriers to sustainable agriculture and a healthy environment. Poverty is easily defined but ignorance is more complex; interrelationships among disciplines is a common area of ignorance. Poverty and ignorance do not always go together but the combination can be lethal. Although ignorance and poverty are common in the third world, considerable of each exist in the USA. Erroneous ideas and educated ignorance must be subjected to ongoing research. The overused ecosystems of the world may collapse unless ignorance and poverty are both conquered.

ISSN:0010-3624    

DOI:10.1080/00103629409369008

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Use of synthetically formulated fertilizers is perceived as not being environmentally sound. This is not the case when principles outlined in special rules are followed. Following the rules is the road to sustainability and not away from sustainability. Simple procedures, such as choice of plant species and cultivar, can do much to modify the needs for various inputs. Plant nutrients obey environmental rules or laws; they enter into geochemical and biological cycles. The application of fertilizers sets into action a chain of events, the consequences of which may be far removed from where they were applied on the farm. These reactions and their ecological implications must be properly managed to avoid problems. Most environmental problems related to soil result from so‐called Liebig‐type limiting factors which prevent response to needed inputs. Any inputs are then wasted and may degrade the environment.

ISSN:0010-3624    

DOI:10.1080/00103629409369009

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Excess soil acidification caused by fertilizers is a major factor in world‐wide soil deterioration. Fertilizers, particularly nitrogen, acidify soil mostly when too much is used (in excess of crop needs). Acidity is otherwise caused by differential cation‐anion uptake by plants which varies with species. A crop can acidify the soil whether or not commercial fertilizers are used, like if the nitrogen came from the soil organic matter or from symbiotic nitrogen fixation. When the exact amount of nitrogen that is needed is applied to land, little acidification results unless nontillage is practiced to give soil surface acidification. In that case the acidification can equal the theoretical. For ammonium‐N, the theoretical is twice the value given in fertilizer handbooks and if there are no plant roots in the soil surface, the full acidification effect is expressed. There are plant species and cultivar differences on soil acidification caused by differential cation‐anion uptake. Legumes acidify soil considerably.

ISSN:0010-3624    

DOI:10.1080/00103629409369010

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In the 1970s an extensive fertilizer trial was conducted on a large number of farmers’ fields in Greece. Nitrogen and phosphorus at different levels were applied to five different crops. Almost half of the fields responded very little to nitrogen and very few to phosphorus. The yields were such that other limiting factors could be part of the reason for the poor responses, but the biggest reason was over‐application in prior years. Estimates of unused nitrogen varied from 56 to 99 percent, and its fate was not determined. Ecological problems could result. The tests indicate urgent need for soil testing to avoid fertilizer use where it is not needed. Advantages include economics and a better environment.

ISSN:0010-3624    

DOI:10.1080/00103629409369011

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Rules that regulate the labeling of fertilizers and amendments are more designed to protect users from fraud than from environmental problems. Users deserve to know concentrations of all elements, essential or non‐essential, in products that they apply to their land. Labels contain warnings when boron or molybdenum are high enough to give toxicities; but with or without warning, concentrations of other elements above certain limits should also be posted. Even posting 0.0000 percent or less if applicable would be helpful. Availability data should also be given. Elemental concentrations should also be posted for amendments which sometimes could be given on the volume basis when necessary. Nutrient and non‐nutrient concentrations or ranges need to be known for amendments not classified as fertilizers. Fertilizer laws need to be adjusted to make this possible. Organic amendments should have a posted concentration or range of concentrations for organic carbon.

ISSN:0010-3624    

DOI:10.1080/00103629409369012

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Desert ecosystems are fragile. Arid lands easily deteriorate under modest impact, and the process of human‐induced decrease in their stability is calleddesertification.Desert ecosystems are characterized by a number of harsh abiotic conditions, such as heat, drought, wind, salt, occasional floods, high‐lime and/or rocky and sandy soil. These combined in various groupings, sometimes with intense animal activity, make for the fragile ecosystems so easily subject to desertification when arid lands are cultivated. When human‐made stresses are further superimposed upon these stresses, results can be devastating because of the additive and synergistic nature of the stresses. Even non‐arid lands are subject to desertification because of mismanagement. Destruction of vegetation can change climate and accompanying soil erosion can create desert conditions. Salinity is a major cause of desertification in irrigated lands. Air pollution is another.

ISSN:0010-3624    

DOI:10.1080/00103629409369013

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Certain specific water‐soluble polymer soil conditioners are economically usable to stabilize soil aggregates to give several important benefits which improve the environment: dust control, water erosion control, an aid to reseeding and reyegetation of severely damaged land, a means of giving a better start to low‐tillage farming, an extender and magnifier of organic matter soil amendments, increased water‐use efficiency to conserve water, increased survival of transplanted trees and shrubs, making it easier to use reclaimed and low‐quality water for irrigation, protecting highways from mud in farm localities and improved success in land reclamation.

ISSN:0010-3624    

DOI:10.1080/00103629409369014

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Agriculture has failed to be sustainable several times in the history of the world because of soil failure (Rush, 1987). Irrigated soil eventually leads to sodicity and salinity unless extreme care is taken. Gypsum is a key ingredient for the maintenance of agriculture on many soils. Waste‐product gypsum is available in a large number of locations at very little or no cost. Advantages of gypsum in addition to prevention and correction of sodicity include greater stability of soil organic matter, more stable soil aggregates, improved water penetration into soil, and more rapid seed emergence. Gypsum and water‐soluble polymers magnify the value of each other. Together they have an important role in making a better environment, especially for growing plants.

ISSN:0010-3624    

DOI:10.1080/00103629409369015

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor