الفهرس 
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Abstract
5. Two field experiments were conducted in the Agricultural Research and Experimental Center, Faculty of Agriculture at Moshtohor, Banha University during 2007/2008 and 2008/2009 seasons.
The aim of this study was to evaluate some intensive cropping sequences versus some conventional ones.
The effects of these cropping sequences on water use efficiency and spread of weed and nematodes as well as soil physical and chemical characters were considered.
The soil of experiments was clay in texture, with a pH value of 7.8 and 2.015 % O.M. content.
The evaluated crop sequences were 10, including:
(1) Wheat /maize. (2) Wheat / Soybean. (3) Wheat/Maize intercropped with Soybean. (4) Faba bean / Maize. (5) Faba bean / Soybean. (6) Faba bean / Maize intercropped with Soybean. (7) Faba bean /summer Maize intercropped with fall Maize. (8) Clover / Maize (9) Clover / Soybean. (10) Clover / Maize intercropped with Soybean.
The results could be summarized as follows:
I. Effects of the experimental treatments on physical and chemical properties of the soil:
1- The 3 preceding cropping winter crops significantly affected bulk density and porosity % in maize plots. Legumes in general and Faba bean in particular reduced bulk density and increased porosity % in soil of succeeding maize with significant differences compared with wheat.
2- The chemical soil characters (O.M. %, total N%, available N%, total K% and available K%) significantly increased in maize plots after legumes compared with wheat. On the other hand, total as well as available P% in maize plots significantly increased after wheat compared with faba bean and clover.
3- Intercropping maize with soybean significantly reduced bulk density and increased porosity% in intercropped maize soil compared with pure stand.
4- Intercropping maize with soybean significantly increased O.M.%, total N%, available N% and total K% in the soil compared with pure stand maize. On the other hand, total P% as well as available P% were reduced due to intercropping.
5- Growing soybean after winter legumes significantly reduced bulk density and increased soil porosity % in soybean plots compared with wheat.
6- Soil chemical properties of soybean plots were improved when soybean followed faba bean and clover compared with wheat. O.M. %, total and available N% and total and available K% in soybean plots were higher when soybean followed faba bean and clover compared with wheat. On the other hand, total as well as available P% in soybean grown after wheat were greater than after legumes.
7- Intercropping maize and soybean significantly increased soil bulk density and reduced porosity % in soybean plots compared with pure stand plots.
8- Intercropping significantly reduced O.M. % and total N% in soybean plots compared with pure stand.
9- The interaction between preceding crops and intercropping significantly affected bulk density, porosity%, O.M. % (in 2009), total N% (in both seasons), total P% (in 2009), available N% (in 2009), available P% (in 2009) and available K% (in 2009), in maize plots.
10-The interaction between preceding crops and intercropping significantly affected soil bulk density, porosity %, and available P % (in 2009) in soybean plots.
II. Effect of experimental treatments on fresh and dry weight of weeds at harvest:
1- Growing maize after clover markedly reduced the spread of annual broad-leaved, grassy as well as total weeds, expressed as fresh weight or dry weight in g / m2 at harvest, compared with maize grown after wheat or faba bean.
Wheat as preceding crop for maize significantly increased dry weight of total weeds by 68.7 and 143.3 % compared with faba bean and clover, on the average of 2008 and 2009 seasons, respectively.
2- Growing soybean after wheat significantly increased weed density expressed as total dry weight of weeds at harvest (in g / m2) compared with faba bean and clover by 63.0 and 53.4 %, on the average of 2008 and 2009 seasons, respectively.
3- Intercropping maize and soybean significantly reduced the spread of total dry weight of weeds on the average of 2008 and 2009 seasons by 75.9 % in maize plots at harvest, compared with pure stand maize. Also, intercropping maize and soybean significantly reduced the spread of weeds in soybean plots at harvest expressed as dry weight of total weeds, compared with soybean in pure stand by 32.9 %, on the average of both seasons.
III. Effect of experimental treatments on the nematode population in maize and soybean:
1- The total nematode population in maize grown after wheat was higher than after legumes. The soil of maize after wheat contained about 60% more nematode population compared with faba bean and clover. Heterodera sp. after wheat was 71 and 95% greater than after faba bean and clover, on the average of both seasons, respectively.
2- Growing maize after legumes markedly reduced the population of stunt nematode of genus Tylenchorhynchus compared with wheat.
3- The highest nematode population in soybean plots was recorded when it was preceded by wheat and the lowest population was after faba bean, and after clover it was in-between.
4- Intercropping maize and soybean markedly increased nematode population in both intercrop components compared with sole cropping.
IV. Effect of preceding crops on growth and yield of maize:
1- Tasseling and silking dates were earlier when maize was grown after clover and faba bean compared with wheat.
2- Maize plants which were preceded by faba bean or clover were taller than those grown after wheat. Also ear height was greater after legumes than after wheat.
3- Stem diameter, area of the topmost ear leaf and number of green leaves per plant were significantly greater in maize plants following legumes compared with wheat.
4- Barreness % was significantly reduced (in one season), and plants carrying two ears % were significantly increased when plants were grown after legumes compared with wheat.
5- Ear length, ear diameter, number of grains / row, ear weight, grain weight per ear, shelling % and 100-grain weight were significantly increased when maize was grown after faba bean or clover compared with wheat.
6- Growing maize after faba bean or clover significantly increased grain yield by 16.24 and 14.05 %, respectively compared with wheat, on the average of 2008 and 2009 seasons. On the other hand, straw yield of maize was not significantly affected by the preceding winter crops.
7- Biological yield in t/fed of maize significantly increased by 4.67 and 3.35 % when maize was grown after faba bean and clover, on the average of both seasons, respectively, when compared with wheat as preceding winter crop.
8- Harvest index in maize was significantly increased when maize was grown after legumes compared with maize following wheat.
9- Total CUs produced from maize grown after faba bean and clover significantly exceeded those produced from maize following wheat. CUs of maize after faba bean and clover an average increase in both seasons of 12.33 and 10.33 %, respectively compared with wheat.
10- Protein % in maize kernels recorded significant increase when the preceding crop was faba bean or clover.
11- Water consumption (m3 / fed) significantly reduced when maize followed legumes.
V. Effect of intercropping on maize:
1- Intercropping maize and soybean induced earlier silking of maize plants in the second season. On the other hand, Tasseling was not significantly affected.
2- Plant height as well as ear height of maize were significantly reduced due to intercropping with soybean.
3- Stem diameter was significantly reduced by intercropping in 2009 season. Area of top most ear leaf was significantly reduced due to intercropping in 2008 season as a result of the competition resulting from the increase in maize population density in intercropped plots.
4- Number of green leaves per plant, barreness % and percentage of plants carrying two ears were not significantly affected by intercropping maize with soybean.
5- Ear length, ear diameter, number of grains per row, ear weight, grain weight per ear and 100-grain weight, were favorably affected by intercropping with soybean. On the other hand, number of rows per ear and shelling % were not significantly affected.
6- Grain yield (expressed as actual yield) of pure stand maize outyielded intercropped yield by 38.5 and 34.8 % in 2008 and 2009 seasons, respectively. Since intercropped maize occupied 50% of the pure stand area, the comparison should be mode with the ”adjusted yield”. The ”adjusted grain yield” showed a marked yield advantage of 44.3% in the first season, being 48.3% in the second one, due to intercropping.
7- The ”adjusted straw yield” indicated an increase of 43.0% in both seasons due to intercropping. Also, biological yield ”adjusted” for actual grown area recorded an increase of 43.5 and 47.4 % due to intercropping over pure stand yield in the first and second season, respectively.
8- Intercropping significantly increased harvest index (in 2009), and total CUs produced (calculated on area unit basis).
9- Protein content in maize kernels significantly increased due to intercropping with soybean in 2008 season.
10-Water consumption was increased due to intercropping by 4.6 and 6.0 in the two successive seasons, respectively.
VI. Effect of the interaction between preceding crops and intercropping in maize:
1- The interaction between preceding crops and intercropping significantly affected silking date, plant height, area of topmost ear leaf (in 2009), number of green leaves/ plant, percentage of plants carrying two ears (in 2008), ear length (in 2008), ear diameter, number of grains/row, ear weight, grain weight/ear, shelling % (in 2008), 100-kernel weight, straw yield, water consumption and protein % (in 2009).
2- The best combination was that between faba bean or clover as the preceding winter crop and intercropped maize.
3- The lowest water consumption was that of pure stand maize after a winter legume.
VII. Effect of preceding crops on soybean:
1- Plant height, number of branches/plant, pods weight/plant and seed yield/plant were significantly higher when soybean was grown after a legume compared with wheat.
2- Weight of 100 seeds significantly increased after faba bean and clover compared with wheat in 2008 season.
3- Seed yield of soybean (t/fed) was significantly increased by 18.40 and 14.70%, on the two seasons average when soybean followed faba bean and clover, respectively compared with soybean after wheat.
4- Straw yield of soybean was not significantly affected by the preceding winter crops.
5- Biological yield was significantly increased in 2008 by 9.8% when soybean was preceded by faba bean compared with wheat. Also, when clover was preceding crop, biological yield recorded an increase of 8.7% compared with soybean following wheat in 2008.
6- Water consumption (in m3/fed) was increased by 2.8% and 2.5% when wheat was the preceding crop compared with faba bean , respectively, on the two seasons average.
7- Total CUs produced per fed were significantly increased by 14.8 and 11.40 %, on the two seasons average when soybean following wheat.
8- Oil % of soybean seeds was significantly higher when wheat was the preceding crop compared with faba bean and clover. On the other hand, seed protein content of soybean following legumes was significantly higher than after wheat.
VIII. Effect of intercropping on soybean:
1- Plant height was not significantly affected by intercropping. Number of branches per plant was reduced due to intercropping in 2009 season.
2- Pods weight /plant, seed yield/plant (in both seasons) and 100-seed weight (in 2008) were significantly reduced by intercropping compared with pure stand.
3- Seed yield of soybean was significantly reduced by intercropping. But ”adjusting” the yield according the occupied area revealed that the seed yield was not affected by intercropping in both seasons.
4- The ”actual yield” of straw was significantly lower than in pure stand, but ”adjusting” the yield on unit area basis indicated a marked increase in straw yield due to intercropping. The ”adjusted yield” of straw indicated increases of 16.6 and 26.7 % in the first and second season, respectively compared with sole cropping.
5- Biological yield ”adjusted on unit area basis” revealed increases of 10.2 and 15.0 % in the first and second season, respectively due to intercropping soybean with maize.
6- Water consumption was reduced by 3.7%, on the average of both seasons, due to intercropping.
7- Total CUs ”adjusted” on basis of occupied area, were increased due to intercropping by 4.20 and 3.3 % in the first and second seasons, respectively compared with sole cropping.
8- Intercropping resulted in an increase in oil % in soybean seed, but seed protein content was adversely affected by intercropping.
IX.Interaction between preceding crops and intercropping on soybean:
1- The interaction between preceding crops and intercropping significantly affected number of branches/plant (in 2008), biological yield (in 2009), and water consumption in both seasons.
2- The lowest water consumption was recorded by intercropped soybean with maize and the preceding crop was faba bean. The highest water consumption was recorded by pure stand soybean following wheat.
X. Competitive relationships and yield advantage of intercropping:
1- LER of the three intercropping patterns recorded an advantage for intercropping maize and soybean. Higher values were recorded when legumes were the preceding crops. On the average of both seasons, intercropping maize and soybean produced a yield advantage of 18.8, 25.0 and 25.4% when preceding crop was wheat, faba bean and clover, respectively.
2- The contribution of maize in the yield advantage was 59.6% compared with 40.4 % for soybean on the two seasons average.
3- Relative crowding coefficient (K) ranged between 2.409 and 2.904 in the first season and between 2.104 and 3.226 in the second season.
4- The greatest (K) values were recorded when the preceding crop was clover and the lowest values were after wheat. In all cases maize produced greater (K) values than soybean, showing greater competitive ability.
In 4 treatments, soybean recorded lower (K) values as the unity (less than one), and greater than the unity in 2 treatments only.
5- Aggressivity (A) values showed that in all cases maize was the dominant component and soybean was the dominated partner.
XI. The Biological Evaluation:
The results revealed that the biological evaluation of both seasons was identical and the arrangement of the 10 crop sequences was similar.
These sequences could be arranged in a descending order as follows: (average of two seasons).
First- Sequence (10), clover/intercropped Maize and Soybean, recorded 103.64 CUs, contribution of clover: maize: soybean, 58.6%: 27.7%: 13.7%.
Second-Sequence (8), Clover/Maize, recorded 99.27 CUs, contribution of clover: maize, 61.2%: 38.8%.
Third- Sequence (9), Clover/Soybean, recorded 87.35 CUs, contribution of clover: soybean, 68.5%: 31.5%.
Fourth- Sequence (7), Faba bean/ Maize/Maize, recorded 85.45 CUs, contribution of faba bean: maize (summer): maize (fall), 24.2%: 45.0%: 30.8%.
Fifth- Sequence (3), Wheat/intercropped Maize and Soybean, recorded 73.8 CUs, contribution of wheat: Maize: soybean, 48.5%: 34.6%: 16.9%.
Sixth- Sequence (1), Wheat/Maize, recorded 71.25 CUs contribution of wheat: maize, 49.8%: 50.2%.
Seventh- Sequence (6), Faba bean/ intercropped Maize and Soybean, recorded 64.2 CUs, contribution of faba bean: maize: soybean, 31.9%: 45.1% 23.0%.
Eight- Sequence (4), Faba bean/Maize, recorded 60.52 CUs, contribution of faba bean: maize, 34.2%: 65.8%.
Ninth- Sequence (2), Wheat/Soybean, recorded 60.37 CUs, contribution of wheat: soybean, 59%: 41%.
Tenth- Sequence (5), Faba bean/Soybean, recorded 48.87 CUs, contribution of faba bean: soybean 42%: 58%.
Clover was a good contribution in any sequence and intercropping maize with soybean was very effective in raising land use efficiency.
XII. Monetary Advantage:
1- The economical evaluation expressed as net income in £.E. per fadden produced by the 10 evaluated sequences, on the two seasons average revealed the following arrangement, in a descending order:
1-Sequence(10) recorded £.E.8671
2-Sequence (8) recorded £.E.7517
3-Sequence (9) recorded £.E. 6854
4-Sequence (3) recorded £.E.6790
5-Sequence (1) recorded £.E. 6143
6-Sequence (2) recorded £.E.5529
7-Sequence (6) recorded £.E. 4494
8-Sequence (7) recorded £.E.3825
9-Sequence (4) recorded £.E. 3613
10-Sequence (5) recorded £.E. 2925
2- Sequence 10, 8 and 9 ranked the first three positions in the economical as well as in the biological evaluation, supporting their superiority
XIII. Water use efficiency of the crop sequences:
1- Water use efficiency expressed as CUs produced per 1000 m3 of irrigation water per fed, on the average of both seasons indicated the following arrangement of the 10 crop sequences:
Seq. 10 (recorded 20.63 CUs), Seq. 8 (recorded 20.11CUs),
Seq. 3 (recorded 19.09 CUs), Seq. 1 (recorded 18.96 CUs),
Seq. 6 (recorded 17.93 CUs), Seq. 4 (recorded 17.29 CUs),
Seq. 9 (recorded 17.06 CUs), Seq. 7 (recorded 17.04 CUs),
Seq. 2 (recorded 15.13 CUs), Seq. 5 (recorded 13.27 CUs).
2- The best sequences, namely, sequences 10 and 8 indicated the superiority of clover followed by maize intercropped with soybean or maize in pure stand.
3- The evaluation of WUE in £.E. produced per 1000 m3 water/fed indicated the following arrangement of the 10 sequences in a descending order:
Sequence3 (recording £.E.1751), sequence10 (recording £.E.1726),
Sequence1 (recording £.E.1626), Sequence 8 (recording £.E. 1473)
Sequence 2 (recording £.E.1382), Sequence 9 (recording £.E.1338)
Sequence 6 (recording £.E.1254), Sequence 4 (recording £.E.1031)
Sequence 5 (recording £.E.795) and Sequence7 (recording £.E.763.
Conclusion:
Legumes as preceding crops for maize and soybean were superior than wheat in reducing soil bulk density, increasing porosity %, enriching the soil with O.M., N and K and reducing the spread of weeds and nematodes in succeeding maize and soybeans. Legumes favorably affected growth, yield components and grain yield and reduced water consumption in maize compared with wheat. Intercropping positively affected soil properties, grain and seed yield of both components when yield was adjusted on area unit basis and reducing the spread of weeds and nematodes in succeeding maize and soybeans. Biological and monetary advantage evaluation indicated the superiority of clover as a preceding crop. WUE indicated the superiority of sequences including maize intercropped with soybean after wheat and clover.