Indiais the seventh largest country by area having second largest population in theworld. Our cultivated land is limited while our population is growing atenormous rate. After independence the number of persons, supported by eachhectare of cultivable land has increased by three times but the Per hectareproductivity is more or less constant. Increase needs for enhanced cropproductivity due to ever increasing population necessitated the breeding ofhigh yielding verities of crops which require high amount for nutrition Increasein agricultural productivity is required to meet the growing demand ofagri-produce.
It could be increased by the use of fertilizers and pesticides.However, there is currently great concern about the damage caused to the environmentby these compounds. Therefore the development of new strategies for theimplementation of effective and safe agricultural chemicals has become moreimportant in recent years. This could be achieved in the form ofcontrolled-release formulation specially based on polysaccharides. Theseformulations not only release the active compound in a slow manner but also afterdegradation increase the crop output besides proving the water-holding capacityof the soil. Release systems decrease the amount of active ingredient availablefor leaching and volatilization.
These formulations will control theenvironment, ecosystem and health hazard scaused by the conventional pesticideformulations. Hence, these polysaccharide based formulations could be utilizedfor the safe management of agrochemicals which will decrease their toxiceffects and helpful for their better delivery to the field.Nitrogenlosses and the impact of those losses on water contamination may be reduced byimproving N fertilizer management and other cultural practices to increase efficientN use by crop plants.
Managementstrategies to reduce soil N loss include improved timing of N fertilizerapplications, better use of soil and plant testing procedures to determine Navailability, switching to use of variable-rate N fertilizer applications andother more effective N fertilizer application methods, application of nitrificationor urease inhibitors, and use of N fertilizer sources that are suitable for localenvironmental conditions (Dinnes et al., 2002). slow release formulationsminimize environmental impact by reducing agrochemical leaching, volatilizationand degradation.
Best services for writing your paper according to Trustpilot
For example,50% ofthe encapsulatedinsecticide chlorpyrifos isreleased in 5 days, whereas free chlorpyrifos is released in 1 day. (2) Slowrelease formulations increase the water-holding capacity of soil. (3) Slowrelease formulations better control weeds in the long run. (4) Polymer-clayformulations store ionic plant nutrients. (5) Polymer hydrogel formulationsreduce compaction, erosion, and water run-off. Agron. Sustain. Dev.
(2015) 35:47–66 DOI 10.1007/s13593-014-0263-0Slow-or controlled-release fertilizer: A fertilizer containing a plant nutrient in aform which delays its availability for plant uptake and use after application,or which extends its availability to the plant significantly longer than areference ‘rapidly available nutrient fertilizer’ such as ammonium nitrate orurea, ammonium phosphate or potassium chloride. Such delay of initialavailability or extended time of continued availability may occur by a varietyof mechanisms. These include controlled water solubility of the material bysemi-permeable coatings, occlusion, protein materials, or other chemical forms,by slow hydrolysis of water-soluble low molecular weight compounds, or by otherunknown means. Tandan2010Useof slow-release N fertilizers to mitigate N losses Slow-releasefertilizers (SRF) are being tested for use with agronomic crops as an alternativeto conventional N fertilizers in order to improve NUE and decrease N losses tothe environment.
There are two maintypes of slow-release N fertilizers with different modes of action: 1)condensation products of urea and urea-aldehydes (e.g. urea-formaldehyde,urea-crotonaldehyde, and urea-isobutyraldehyde based products) and 2) coatedurea fertilizers (e.g. sulfur-coated, polymer-coated, and a mix of sulfur andpolymer-coated urea) (Trenkel, 1997).
Barbieriet al. (2006) compared the effects of SRF urea and conventional urea underno-tillage on corn yields. Their resultsshowed no significant differences between fertilizers in neither grain Ncontent nor NUE, although SRF urea treatments had higher NUE than treatmentswith non-coated urea. Any approach that will increase nutrientuse efficiency (NUE) may lead to a reduction in the amount of applied fertilizer per unit area. This in turn should contributeto the reduction of potential pollution problems by decreasing fertilizerproduction. One reservation regarding the use of SRF/CRFs forreducingenvironmental problems related to fertilizer production is the extent to whichthe various materials used for preparing SRF/CRFs (plastics, formaldehydes,sulphur, etc.) contribute to environmental pollution.One possible way toimprove nutrient and particularly nitrogen use efficiency while reducing theenvironmental hazards is by using controlled release or slow releasefertilizers (Hauck, 1985; Shaviv and Mikkelsen, 1993; Peoples et al.
, 1995; Bockmanand Olfs, 1998; Shaviv, 1999) Nitrogenuse efficiency Nitrogen use efficiency (NUE) is theproportion of N inputs that are removed in harvested crop biomass, contained inrecycled crop residues, and incorporated into soil organic matter and inorganicN pools (Cassman et al., 2002). Nitrogenuse efficiency values of approximately 37% have been reported for cereal cropsin the USA (Cassman et al., 2002) while others have estimated cereal NUE indeveloped countries to be approximately 42% with worldwide NUE is approximately33% (Raun and Johnson, 1999).
In the last 25 years, NUE has generallyimproved in USA corn systems due to: 1)better fertilizer management that includes a shift of fall to spring applicationand use of split fertilizer applications over the growing season rather than asingle large preplant application; 2) increased yields and better crop growthas a consequence of greater stress tolerance of hybrids, and 3) conservationtillage practices and higher plant densities (Cassman et al., 2002). nutrientuse efficiency (NUE) can be considered as the amount of nutrients taken up fromthe soil by plants and crops within a certain period of time compared with theamount of nutrients available from the soil or applied during that same periodof time.
Improving NUE in agriculture has been a concern for decades(Dobermann, 2005), and numerous new technologies have been developed in recentyears to achieve this. The types of fertilizers and their management inagriculture will be at the forefront of measures to improve the global Nbalance in the short- and long-term.Nitrogenuse efficiency is of significant importance in crop production system due toits impact on farmer economic outcomes and environmental impact. Nitrogen useefficiency also, may be reduced in crop production due to many factorsincluding losses of soil nitrogen by volatilization, leaching anddenitification. Jokela and Randall (1989) conducted a study of the effects of Napplication rate on residual NO3-N in non-irrigated corn and concluded thatwhen N rate was increased, soil NO3 -N was also higher. Another study showed no significantdifferences in soil NO3 -N among several N fertilizer rates, although there wasa clear trend of higher soil NO3 -N levels with the highest fertilizer Napplication which may cause accumulation in the soil profile and leaching intogroundwater in the long term (Elmi etal., 2005)Jokela,W.E.
and G.W. Randall. (1989).
Corn yield and residual soil nitrate as affectedby time and rate of nitrogen application. Agron. J. 81:720-726.Elmi,A.A.
, T. Astatkie, C. Madramootoo, R. Gordon, and D. Burton. (2005). Assessmentof denitrification gaseous end-products in the soil profile under two watertable management practices using repeated measure analysis. J.
Environ. Qual.34: 446-454Fertilizers constitute an integral part of improved crop productiontechnology (Saifullah et al. 2002).
Nitrogen (N) is major factor limiting yieldof wheat (Andrews et al. 2004). Optimum N management to wheat is important formaximum yield, optimum water utilization and minimum contamination toenvironment (Corbeels et al. 1999).There is need to reduce use of N fertilizerapplication and search for genotypes with greater N use efficiencies, either ina strict physiological or agronomic sense (Andrews et al. 2004).
The efficiencyof wheat cultivars to N use has become increasingly important to allowreduction in N fertilizer use without decreasing yield. Phosphorus is essentialfor enhancing seed maturity and seed development (Ziadi et al. 2008). Both Pand K application favored tillering of wheat and reduced lodging in wheat(Liakas et al. 2001), improved photosynthetic activity and transport to theripening grains.
This resulted heavier grains (Zhang et al. 1999). Withadequate application of phosphorus, 20% more grain yield of wheat can beobtained (Ascher et al. 1994).
N and P uptake could be enhanced with increasedP applications (Jiang et al. 2006).). Differentresearchers recommended different P application rates. Chaturvedi (2006) found28.5 kg P ha-1 as optimum for growth, plant height, tillers, grains spike-1,1000 grain weight, grain and straw yields.
Jiang et al. (2006) observed 108 kgP ha-1 for higher leaf area index, tillers, ear bearing tillers and dry matteraccumulation. Khalid et al. (2004) applied 45 kg P ha-1 in wheat and obtainedmaximum emergence, productive tillers, grain yield and biological yield.Potassium is a one of special significance because of its active role inbio-chemical functions of plant e.
g. activating various enzymes, proteinformation, carbohydrates and fat concentration, tolerance to drought andresistance to frost, lodging, pests and disease attack (Marschner, 1995). ThusK deficiency in soil may results in yield losses (Ali et al. 2008). Increase incropping intensity and introduction of high yielding fertilizer responsivecultivars have resulted in a considerable drain of soil K reserves.
In thepresent day, intensive and high yield oriented agriculture, there is a negativeK balance and soils are being mined for this essential element (Tan et al.2005). Increased use of N without adding required K in soil has furtheraggravated K deficiency (NFDC, 2003) because K play important role inimprovement of the growth indices. Increasing K amount in wheat grain increaseddry matter, 1000-grain weight, tillers, K contents in plant, The demand for plant nutrients isexpected to increase continuously withpopulation growth (Kaarstad, 1997; Keeney, 1997), particularly in developingcountries. According to Keeney (1997), world population is expected to increaseby about 2.3 billion by 2020 and double by the year 2050. If meat and foodconsumption in developed countries is matched by the rest of the world by themid-21st century, then grain and nutrient demand is expected to triple (Keeney,1997; Kawashima et al.
, 1997). Keeping in mind that the amount of land used forfood production changed very slightly over the past few decades (Kaarstad,1997; FAO, 1999), and may even have decreased in parts of the world due tourbanization (Keeney, 1997), the nutrient load per unit area is steadilyincreasing. All this implies that food production will have to be much moreintensive and efficient than ever before.
