الفهرس 
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Abstract
The Objective of this current work is to study Organic matter decomposition under clean agriculture system in sandy soil using nuclear technique. This desirtatation has the following targets:
- Amendment and improving sandy soil properties
- Utilization of farm wastes (Recycling) in safe mode
-Benefits form organic matter decomposition.
- Follow up the fate of same nutrients (Nitrogen) released in soil media after organic matter (O.M) decomposition and Impact on plant nutrition status.
-saving the environment on short and long run.
The valuable results obtained in the present study could be summarized as follows:
Part one: incubation Experiment
Carbon to nitrogen ratio: C: N values tented to decrease with time up to 45 days of incubation. The organic materials treatments could be ranked as the followings: chickpea straw < cow manure <wheat straw <maize stalk .At the some time, fungi behavior could be as follow: Aspergillus (32.9:1) < trichoderma (33.1:1)< uninoculated (33.4:1) < dual inoculants (34:1).
Organic matter: (O.M %) values of O.M tended to decrease up to 45 days of incubation. The priorities of fungi inoculation treatments could be ranked as the following: Dual inoculants (66.3) > uninoculated (57.5) > Aspergillus (57.2) > trichoderma (57.1) mgkg-1soil. In addition, at any given time, the amount of organic matter content as affected by decomposed residues could follow the ascending order: Maize stalk (62.4) > Wheat straw (61.2) > Cow manure(53.8) > Chickpea straw (53.6) mg kg -1 soil.
Phosphors content mg kg-1 soil: The overall mean of time intervals indicated that the highest amount of P was induced by application treatments at 45 day period while the lowest one was noticed after 1day of incubation .The organic materials treatments could be ranked as the following: Maize stalk > wheat straw> cow manure> chickpea straw. Concerning the fungi inoculation there was no significant differences between the treatments ,The priorities of fungi treatments could be ranked as the following: uninoculated > Aspirgilles> dual inoculants >trichoderma
Potassium content mg kg-1 soil: In this respect, the highest value of Potassium (81.3 mg kg-1) content was recognized at 45 day of incubation. The overall average showed the superiority of uninoculated over dual inoculums Trichoderma and Aspirgilles inoculants. Concerning the organic additives, the average indicated the superiority of cow manure over the all other additives. In this regard, it could be ranked as the follows: wheat straw > chickpea straw > maize straw cow manure.
Gross N mineralization content: gross N mineralization tended to increased by increasing incubation intervals up to 30 day then gradually increased up to 45 day intervals. The overall average showed that of dual inoculants and Trichoderma inoculants nearly closed to each other when gross N mineralization was concerned. Concerning the organic additives, the average indicated the superiority of chickpea straw over the all other additives. In this regard, it could be ranked as follows: chickpea straw > cow manure > maize stalk > wheat straw data recorded was 50.6, 38.8, 28.4 and 22.1 mg kg-1 .
Net N immobilization content: Net N immobilization tended to increased by increasing incubation intervals up to 30 day then decreased up to 45 day intervals. The overall average showed that of Aspergillus and uninoculated nearly closed to each other when net N immobilization was concerned. Concerning the organic additives, the average indicated the superiority of chickpea straw over the all other additives. In this regard, it could be ranked as the follows: cow manure> chickpea straw >maize stalk > wheat straw data recorded was 32.2, 26.2, 19.9 and 14.6 mg kg-1 respectively.
Part two: Intercropping Field Experiment
Grains yield of wheat plant: Intercropped wheat has a high grains yield as compared to those recorded under sole crop. In conclusion, the application of intercropping system induced an increase of wheat grain yield against the sole system. regardless the cultivation system, the over all means of fertilizer rates indicated (50% MF + 50% OM) treatment was superiority 100% OM)and ( 75% MF+ 25% OM) or those recorded with either un fertilizer when wheat grain yield considered. Comparison heed between organic sources reflected the superiority of compost under sole cultivation, while chickpea straw was the best under intercropping.
Nitrogen uptake by wheat grains: Intercropped has a high grain N uptake compared to soil systems. While totally organic materials had accumulates more N in grains than those of untreated treated control. In the same time, the overall mean indicated the superiority of compost treatment combined with 50%mineral fertilizer under intercropping system over those of either only organic materials treatment or those combined with 75% mineral fertilizer.
Phosphors uptake by wheat grains: phosphors uptake by wheat grains was increased under intercropping system as compared to sole system. Generally, P uptake by wheat grains was better under 100% OM than 75% M.F + 25% O.M and or (50% M.F + 50% OM) and 100% M.F treatments. In addition compost treatment seemed to be the best treatment of organic materials addition when P uptake by grains as considered.
Potassium content g/plot in wheat grains: application of intercropping system resulted increase of K uptake by grains as compared to sole system. The K uptake by grains was enhanced by addition of maize stalk, chickpea straw and wheat straw while addition of compost and caw manure resulted in low content of K when compared to wheat plants totally treated with mineral fertilizer and the unfertilized control.
Straw weight of wheat: Plants treated of chickpea straw and compost, achieved the best value of straw weight. Application of intercropping system increased straw weight of wheat plant compared to sole system.
Nitrogen uptake by straw wheat: nitrogen uptake increased under intercropping system compared to sole system. Among the organic manure treatments, chickpea straw and compost seem to be the best ones.
Phosphors uptake by straw of wheat: Plants treatment under intercropping system was increased P uptake by straw wheat when compared to sole system. In addition chickpea straw treatment seemed to be the best treatment of organic materials addition when P uptake by straw considered. Under mineral enrichment, 75%M.F with combination of organic manure 25% was the best treatment where it results in relative increased P uptake by straw of wheat plants.
Potassium uptake by straw wheat: plants treated with totally organic materials had accumulated more K in straw than those treated with totally mineral fertilize and control. Intercropping to be the best system of culture state when K uptake by straw considered.
Seed yield of chickpea: Wheat straw was the best treatment where it results increased seeds of chickpea plant. The over all mean of sole cropping system indicated that the application of wheat straw resulted in higher seed yield (5.474 kg plot -1) than other treatments, while the inter cropping system showed the highest value of seed yield (3.242 kg plot -1) when chickpea straw treatment compared to the other organic additives . (3.744 kg plot -1)
Nitrogen uptake by seeds chickpea: The over all means of N uptake by seeds as affected by fertilizer rates were higer in case of 55 MF plus 50% OM than those recorded with 75% MF.
Phosphors uptake by seeds chickpea: Regardless the organic and mineral fertilizer, the best values of P uptake were obtained under sole cropping system as compared to the intercropping system. Fertilization treatments revealed the superiority of combination of organic sources and mineral fertilizer at a rate of 50% of each when P uptake by seeds was concerned.
Potassium uptake by seeds chickpea: Results showed that K uptake by seeds significant increased as result application of sole system of compared to than intercropping system. For chickpea plant treated with totally organic amendment, the K uptake by seeds was enhanced by wheat straw, chickpea straw and compost while caw manure and maize stalk showed lower content of K when compared to chickpea plants totally treated and with control.
Shoot dry weight of chickpea: plants treated with wheat straw and chickpea straw, resulted in the best value of shoot dry weight. Sole system was better than intercropping system when shoot dry weight was considered. Treatments of 100% M.F and 50% M.F + 50% O.M were the best ones when dry weight chickpea shoot was concerned
Nitrogen uptake by chickpea shoots dry weight: A sole system was superioraer intercropping systems when the N uptake by shoots was considered. Plants treaded with chickpea straw and wheat straw gave the best value of N uptake by shoots of chickpea plants as compared to other treatments and control. The application of 100% MF and 50% O.M + 50% seems to be the best ones when compared to totally organic manure with mineral fertilizer and control.
Phosphors uptake by Chickpea shoots dry weight: In conclusion, plants treated under culture state, sole systems was increased P uptake by shoot of chickpea plants compared intercropping systems. Plants treaded of Caw manure and chickpea straw achieved the best P value uptake by shoot of chickpea plants compared to all treatment and control. The application of 100% MF and 50% O.M + 50%MF seemed to be the best ones when compared to totally organic manure with mineral fertilizer and control.
Potassium uptake by Chickpea shoots dry weight: sole system appeared to be the best system of culture state when K uptake by shoot to compared intercropping system. Chickpea plants treated with totally organic amendment appeared the higher K uptake by dry weight chickpea
Land equivalent ratio of wheat and chickpea plants: Application combination of organic sources and mineral fertilizer, demonstrated that the rates of fertilizer nitrogen has no significantly difference between all treatments as well as control. The treatments could be ranked as follows control > 75% MF +25% OM > 100% OM >100% MF > 50%MF +50% OM, which recorded 1.767, 1.688, 1.639, 1.555 and 1.418, respectively.
Part three : Application of 15N isotope dilution technique
Nitrogen derived from fertilizer (Ndff) shoots and seeds of chickpea plant: The lowest portion of nitrogen derived from fertilizer was resulted from application of compost and chickpea straw treatments . It is worthy to mention that full-recommend dos of fertilizer (20 kg N fed-1) was efficiently used by shoots of chickpea plants. Portion of nitrogen derived from fertilizer by seeds of chickpea was lower than those recorded with shoots.
Nitrogen derived from organic (%Ndfo) shoots and seeds of chickpea plant: Generally, there was no big significant difference between nitrogen gained by shoots and seeds from the organic materials. This holds true with all treatments.
Nitrogen derived from soil (% Ndfs) shoots and seeds of chickpea plant: The application of organic materials to chickpea plant induced declines in the portion of N derived from soil when compared to the plants received totally fertilized with mineral fertilizer. More declines in nitrogen derived from soil percentages were resulted from application of cow manure and compost treatments under different rate of mineral fertilizer, the application 100% MF treatment induced higher nitrogen derived from soil pool as compared to the other treatments.
Nitrogen derived from air (% Ndfa) shoots and seeds of chickpea plant: In case of cow manure and maize stalk, the best value of nitrogen derived from air was detected followed by compost, while the lowest value was recorded with wheat straw. In general, nitrogen derived from air by shoots lower than those uptaken by seeds of chickpea plant.
- Nitrogen derived from fertilizer (%Ndff) straw and grain of wheat plant:
Application of wheat straw and compost treatments were enhanced the nitrogen derived from fertilizer by straw of wheat plant as compared to caw manure, maize stalk, chickpea straw, but Ndff% in grains of wheat , cow manure and maize stalk increased as compared to the other treatment.
- Nitrogen derived from organic (%Ndfo) straw and grain of wheat plant:
Application of organic materials, chickpea straw and cow manure acheavied the highest value of Ndfo% by straw of wheat plant as compared to maize stalk, compost and wheat straw. But values of nitrogen derived from organic in grains of wheat plants, the application of chickpea straw and wheat straw increased as compared to other treatments.
- Nitrogen derived from soil (% Ndfs) straw and grain of wheat plant: The highs percentages of nitrogen derived from soil in wheat were recorded when the maize stalk was added , compared to the other treatment reached to 3.3 % in wheat straw corresponding to 1.9 % in grain with application of cow manure treatment . This hold true with both straw and grains. The portion derived to straw was much more than that derived to grains.
General Conclusion
Decomposition of humus and soil organic matter is slow as a consequence of the low quality of the resource for decomposing organisms. Improvements in temperature and moisture conditions may increase decay rates to some extent, within the bounds set by substrate quality. Organic matter contents are positively correlated, but the relationships between texture and rates of C and N mineralization are less clear. High concentrations of inorganic N may reduce rates of humus decomposition by inhibiting the activity of lignin-degrading enzymes.
Comparison of decomposition, mineralization, and immobilization is complicated by differing definitions of organic matter pools, although all the models have the same broad pattern of a mixture of fast cycling (plant residues and caw manure) and slow cycling (humus) pools. There is general agreement that the processes are controlled by the decomposition rate of soil organic matter and the C: N ratios of materials in the pools.
The benefits of N2 fixation by legumes to cereals growing in intercrops or to grasses growing in mixed swards are high clear. In cases the benefit to the N status of cereals has bee seen when they are intercropped with legumes ,where benefit is found ,it is mainly due to sparing of soil N rather than direct transfer from the legume. Also, the application of 15N isotope dilution technique proved the importance of organic materials as storage of nutrients into mineralization in soil, which acts as a feeding source when needed. The portions of N derived from organic materials and air were exactly determined. The isotopic data indicated the equally dependence of plants (wheat, chickpea) on both mineral and organic N sources.