Effects of Application of Biochar and Arbuscular mycorrhizal fungi on Growth and Chemical Composition of Corn (Zea mays L.704) in a Calcareous Soil

The use of biochar and organic manures have positive effects on soil fertility, crop production and carbon sequestration in soil. However, their effects depend on soil characteristics, plant species and type of the raw material used in the production of biochar. Therefore, the aim of this study was to evaluate the effects of application of organic manures (sheep and paltry) and their biochars, two species of arbuscular mycorrhizal fungi and their interactions on shoot and root dry matter, root colonization percentage, chlorophyll index and uptake of some micro and macro-nutrients by corn in a calcareous soil under greenhouse condition.
To do this research, appropriate amount of soil from surface horizon (0-30) of a calcareous soil was collected, air dried and passed through 2mm sieve. A factorial experiment as a completely randomized design was conducted with three replications. The first factor including organic manure at five levels (without organic manure (C), sheep manure (SM), paltry manure (PM), sheep manure biochar (SMB) and paltry manure biochar (PMB) each at 2 % w/w) and the second factor was fungal inoculation (non-inoculation (NG), inoculation with Funneliformis mosseae (FM) and Glomus versiform (GV)). Biochars were produced using the pyrolysis of organic manures (500 0C during 4 h) in the limited oxygen conditions. After applying treatments, 5 corn seeds were planted at a depth of about 2 cm in plastic pots. During the growth periods, soil moisture content was maintained at about 80 % of field capacity using distilled water. After 10 weeks of plant growth, shoot and root dry matter, chlorophyll index, root colonization percentage and the concentration of nitrogen, phosphorous, potassium, iron, manganese, zinc and copper of shoot were measured. The amount of nutrient uptake was calculated by multiplying the nutrient concentration in shoot dry matter.
The highest increase of root colonization was observed in the GV fungi treatment by 112 %. Also, application of organic treatments (except SMB) increased root colonization percentage significantly. Addition of each four types of organic treatments caused a significant increase in chlorophyll index compared to control, so that, the highest value was observed in the SM treatment. In organic treatments, the sequence of shoot and root dry matter, uptake of nitrogen, phosphorous, and potassium, was as follows: PMB > PM > SMB > SM > Cl. Also, the effect of application of GV fungi on enhancement of above mentioned characteristics was higher than FM fungi considerably. Application of GV unlike FM fungi, led to a significant increase of copper and manganese uptake by 14.7 and 18.6 % compared to control respectively. The sequence of copper and manganese uptake in different organic treatments, was as follows: PMB > PM > SMB > SM > Cl. Among the treatments, only separate application of PMB and FM fungi caused a significant increase of iron uptake compared to control. Application of FM and GV fungi significantly increased uptake of zinc by 15 and 45.4 % compared to control respectively. The sequence of zinc uptake in organic treatments was as follows: PM=PMB > SMB=SM > Cl. The results of interaction effects of treatments showed that the effect of simultaneous application of fungi and organic manure on studied indices were different and depended on type of applied organic manure and mycorrhizae fungi.
The results showed that the use of SMB and PMB were more effective to increase the yield and uptake of nutrients by corn than their raw materials (SM and PM). In general, it seems that simultaneous application of PMB and GV fungi was more effective to improve the most studied factors than other treatments.