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Abstract
This study was carried out at El-Raheb Experiment Farm, Faculty of
Agriculture, Minufiya University, Shibin El-Kom, during the two successive seasons
of 2006 and 2007. In the two experiments, a randomized complete block design with
three replicates was used. We used two mineral fertilizers such as ammonium nitrate
and ammonium nitrate + ammonium sulphate (1 : 1, w/w) and four biofertilizers
namely Rhizobacterin, Nitrobein, Biogene and Microbein at a rate of 2 kg / fed.
besides Farmyard Manure (FYM) and control (unfertilized). The results showed that,
highly significant varietal differences were found among fertilizer treatments, where
mineral fertilizers gave the highest yield of potato by increasing percentage of 124.28
and 100.35 in two growing seasons, respectively and a high marketable yield of potato
had got by organic fertilizer FYM. Tuber grade (A) which weight over 100 g was
observed by ammonium nitrate treatment, grade B (50 ± 100 g) by FYM. Reducing
sugars decreased but non reducing sugars increased significantly. Starch content
increased by FYM and biofertilizer and decreased by mineral fertilizers. Ash content
increased significantly by both mineral fertilizers used, while the fibers content
decreased significantly and this reduction was very high by application of
Rhizobacterin. Dry matter increased by FYM and biofertilizers application but
decreased by mineral fertilizers, where the highest dry matter was achieved by
Nitrobein (25.75%) which gave the highest value of ascorbic acid (16.78 mg/100 g).
High nitrate level was recorded by mineral fertilizers (340.26 mg/kg) and the lowest
value (199.54 mg/kg) by FYM. High yield of pea by FYM and pod weight, seed No. /
pod, weight of seeds (g) / pod increased significantly. Also, FYM gave the highest
values of shelling out, protein content and ascorbic acid while gave the lowest value
of carbohydrates. Also, FYM gave the highest value of total yield of spinach by
increments of 108.11 and 99.42% for two growing seasons, respectively. Microbein
gave the highest ascorbic acid content in spinach, and a high nitrate content caused by
both mineral fertilizers, while FYM gave the lowest nitrate level. Chemical
constituents of potato differed significantly from raw material. Fat content become
26.24% in potato slices fertilized by ammonium nitrate, against 12.34% only for slices
fertilized by Nitrobein. Nitrate level decreased from 14.4 to 3.83% in French fries and
from 12.9 to 1.7% in chips and from 11.10 to 1.86% in cooked potato by soaking it in
0.5% sodium metabisulfite solution. Nitrate in green pea seeds decreased by cooking,
freezing and canning processes. The highest value of loss in nitrate level reached up to
98.04% was recorded in canned pea unfertilized and blanched in boiling water for 3
min. before canning. Nitrate level in spinach affected significantly by the interaction
between fertilization, preservation method, blanching media and cooking process.
Results showed that, FYM treatment gave the highest decrease in nitrate level, while
two mineral fertilizers gave the lowest ones in nitrate level in spinach.