study on the effect of combined application of manure and chemical fertilizers on some properties of thompson novel orange juice

introduction: citrus are one of the important orchard fruit production that after banana is second in production at the world level and every year, chemical fertilizers having most important role in increasing crops productions, but in long application of fertilizers cause soil destructions and polluting underground water. also soils of dry regions are very poor in organic matter level. nowadays in most countries, climatically condition and poor management cause poor organic matter content of soils. in iran more than 60 percent of cultivated lands having less than 0.5 up to 1 percent organic matter. this may be due to intensive cultivation and poor managements for this reason if we have combine applications of manure and chemical fertilizers, the results would be much better. the aim of this research was to evaluate suitable ratio of manure and chemical fertilizer in order to reduce the chemical fertilizer use in citrus orchard in north of iran. materials and methods: this experiment was conducted in one of the orchard at sari district with low organic c. this research carried out on five years old citrus threes. this experiment carried out as factorial experiment on the base of complete randomized block design with 9 treatments and three replications. treatments included three manure levels (0, 6 and 12 kg per tree) and three levels of macro fertilizer including potassium sulphate, ammonium sulphate and super phosphate triple (o, 30 and 60 percent on the bases of soil test). total treatment were 27 plots, (each plots were includes two threes).all treatments were applied at march. all analysis was done with standard methods. this experiment was done as factorial on the bases of complete randomized block design with 9 treatments and three replications. the treatments were as follows: t1: zero percent chemical fertilizer and zero kg manure t2: 30 percent chemical fertilizer (potassium sulphate 50 kgha-1, ammonium sulphate 30 kg ha-1 and super phosphate triple 45 kg ha-1) and zero kg manure. t3: 60 percent chemical fertilizer (potassium sulphate 100 kgha-1, ammonium sulphate 60 kg ha-1 and super phosphate triple 90 kg ha-1) and zero kg manure. t4: zero percent chemical fertilizer and 6 kg manure t5: 30 percent chemical fertilizer (potassium sulphate 50 kgha-1, ammonium sulphate 30 kg ha-1 and super phosphate triple 45 kg ha-1) and 6 kg manure. t6: 60 percent chemical fertilizer (potassium sulphate 100 kgha-1, ammonium sulphate 60 kg ha-1 and super phosphate triple 90 kg ha-1) and 6 kg manure. t7: zero percent chemical fertilizer and 12 kg manure t8: 30 percent chemical fertilizer (potassium sulphate 50 kgha-1, ammonium sulphate 30 kg ha-1 and super phosphate triple 45 kg ha-1) and 12 kg manure. t9: 60 percent chemical fertilizer (potassium sulphate 100 kgha-1, ammonium sulphate 60 kg ha-1 and super phosphate triple 90 kg ha-1) and 12 kg manure. all data analysis was done with mstatc software and mean data comparison done with duncan test levels at 1 or 5 percent levels. results and discussion: the results of analysis of variance showed that simple effect of manure and fertilizers and their interactions had no significant effect on tss, but simple effect of fertilizer and their interactions between them had significant effect. the simple effect of chemical fertilizer and its interaction with manure were significant at 1 percent level on titration able ph of fruit juice and the simple effect of manure effect on fruit juice ph were significant at 5 percent level. the simple chemical fertilizer effect on c vitamin was not significant but simple effect of manure and its interaction effect with chemical fertilizer were significant at 5 percent level. the analysis of variance showed that simple effect of chemical fertilizer on fruit juice potassium were not significant, but simple effect of manure and its interaction with chemical fertilizer were significant at 5 percent level. analysis of variance showed that simple effect of manure and fertilizer on the fruit juice calcium was significant at 1 percent level but their interactions were significant at 5 percent level. simple effect of manure and fertilizer and their interactions on the fruit magnesium, iron manganese, zinc and copper were significant at 1 percent level. analysis of variance showed that simple effect of manure and fertilizer and their interactions on the fruit juice magnesium, manganese, iron and copper was significant at 1 percent level, but simple effect of manure on fruit juice zinc were significant at 5 percent level. conclusion: in this study the treatment with combined application of 30 percent and 12 kg manure had highest ca, mg , fe, mn and zinc concentration in fruit, also combined application of 60 percent fertilizer and 12 kg manure had effect on ph and potassium of fruit juice.