Document Type : Research articles.
Authors
Soils, Water and Environment Res. Institute, Agric. Res. Center, Giza, Egypt
Abstract
This work is an important strategy for understanding the local best usage
of either N-mineral or N-bio-sources, whether be under demand for agricultural
utilization projects. Also, it represents a huge challenge and technical solution
for alleviating the possible adverse fears of human health through
environmental risks as a result of excessive use of the nitrogenous chemical
fertilizers for fertilizing some cereal crops as well as to support the newly
technique of “clean, bio- and organic agriculture”.
So, a field experiment was conducted on a clayey soil during two
successive seasons of 2008-2009 and 2009-2010 at Damas village, Mit Ghamer
district, El-Dakahlia Governorate, Egypt, to identify the outcome of replacing
25 % from the recommended N-mineral dose (RND) of wheat crop by using a
bio-inoculation with Paenibacillus polymyxa bacteria under different rates of
Zn-EDTA (i.e., 0, 1.0, 1.5 and 2.0 kg fed-1 as soil application) on wheat
(Triticum aestivum L., Sakha 93 cv.) vegetative growth as well as harvest
crop parameters, i.e., spike characters, weight of 1000 grain, grain and straw
yields/fed & their nutrient contents of N, P, K, Fe, Mn, Zn and Cu. Soil content
of available nitrogen forms (NH4+ and NO3-) as related to nitrogenase enzyme in
the soil after 70 days from sowing was taken into consideration in this study.
The obtained data show that grain bio-inoculation and Zn-chelate applied,
as shown in the treatment (Paenibacillus polymyxa bacteria + 75 % RND +
highest Zn rate of 2 kg/fed), led to an almost similar plant vegetative
parameters (i.e., plant height, No. of tillers plant-1, dry weight plant-1, leaf
chlorophyll a & b and carotenoids) to those received the full recommended Nmineral dose. However, the relative decrease percentages in such parameters
were negotiable, insignificant and not exceeding 3 %. The reverse was true for
available nitrogen forms (NH4+ and NO3-), mainly due to the pronounced
increase in nitrogenase activity. The corresponding relative increase percentage
in N-forms recorded 18.77 and 8.51 % over the soil treated with 100 % RND,
respectively. That was true, since such increases were more closely attributed to
an achieved increase (53.04 %) in the nitrogenase activity of plant rhizosphere.
A similar way and a parallel trend for the growth parameters were
observed with wheat spike characters (i.e., weight plant-1 and number plant-1),
harvest crop parameters (i.e., grain weight plant-1, straw weight plant-1, weight
of 1000 grain, grain and straw yields fed-1), grain and straw contents of N, K,
Fe, Mn, Zn, and Cu. However, the obtained values of these plant parameters
were achieved negotiable and insignificant differences don't exceeding 2 % at
the treatment of (bio-inoculation + 75 % RND + highest Zn-chelated rate of 2
kg/fed) as compared to those treated with full recommended N-dose.
So, it could be said that the integrated combination between N-biofixation and applied soil Zn-chelated leading to a continuous bio-fixed
nitrogen slow release along the growth stages of wheat plants, to minimize its
possible lose by either leaching process or volatilization, and in turn to
rationalize use of N-mineral fertilizers, which is surplus point for sustainable
agriculture system. Such system represents a new agriculture strategy that
affects the country's economy and its development. That is due to the possible
adverse fears on either crop products or human health should be alleviated,
besides it represents an ideal solution to meet the excessive nitrogenous
fertilizers demand.
Keywords
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