| Matrix is a kind of cultivation medium which is made of various organic and inorganic materials by certain technology.It is a necessary means of production for the development of modern agriculture and the realization of high yield,high efficiency,high quality,safety and standardization of agricultural products.With the development of facility agriculture,the expansion of seedling industry and the increase of urban greening rate,the development of high-yield and efficient substrate will be the basis for the sustainable development of modern agriculture and garden ecological city construction.In recent years,the research on composite matrix is increasing,mainly focusing on the screening of different matrix materials and the research of composite ratio.Due to the variety of raw materials and the regional differences of their sources,only considering the type of raw materials and the proportion of compound,the mechanical composition of the matrix is unstable,which leads to the imbalance of water and gas supply of the matrix,and the product quality is uneven.In this paper,fly ash,vermiculite and peat were used as experimental materials to control the size of particle size.The changes of physicochemical properties of matrix with different particle size and the effects of matrix particle size control on plant growth and development were observed,It can provide experimental data for the precise deployment of roof greening and micro potato matrix production,and also provide technical reference for the absorption and utilization of fly ash and the development of modern matrix production technology based on particle size control.The main results are as follows:1.Particle size affects the pore characteristics and moisture index of composite matrix based on fly ash.The results show that the bulk density of fly ash increases from 0.33 g/cm~3 to 0.79 g/cm~3 with the decrease of particle size from>5 mm to<0.25 mm;the aeration porosity decreases with the particle size,from 48%to 3%;With the decrease of particle size,the water holding capacity increases from 8%to 51%;The pore size ratio decreases with the decrease of particle size.The field capacity increased from 5.83%to 28.19%with the decrease of grain size;The saturated water content decreased from 111.82%to 67.14%with the decrease of particle size.2.In the pot experiment of roof greening plants,the particle size is the main factor affecting the substrate properties and plant growth.The bulk density of 0.25～1 mm and 1～2 mm composite matrix was significantly different.The growth indexes of Sedum Lineare,Sedum spectabile and Ophiopogon japonicus were analyzed.The results showed that the grain size affected the plant growth.Compared with the commercial substrate treatment with the same substrate thickness,the ground diameter growth of Sedum Lineare in the treatment of 0.25-1 mm increased the most,with a maximum increase of 0.39 cm;In the 0.25-1 mm grain size treatment,the plant height growth of Sedum spectabile was the largest,increased by 2-2.83 cm;In the treatment of<0.25 mm grain size,the crown growth of Ophiopogon japonicus was the best,which increased the growth by 1～2.5 cm.According to the comprehensive analysis of plant growth index,when the size of 0.25～1 mm fly ash,10%peat by volume,planting thickness of 15 cm,the overall performance of each plant is good.3.By measuring the physical and chemical properties of fly ash,and comparing with the three-dimensional green cultivation matrix(T/CABEE 005-2020),it is feasible that fly ash is used to prepare the roof green substrate,and will not cause environmental pollution.In the roof greening simulation landscape experiment,the mechanical composition of the substrate has an important influence on the water air balance performance of the substrate.In the simple roof greening type,the proportion of particles<1 mm in B1 treatment was 50%,and that of particles<1 mm in B4 treatment was 80%.The bulk density of B4 treatment was 0.11 g/cm~3 higher than that of B1,with smaller ventilation porosity and larger water holding porosity.Among the garden roof greening types,B2 treatment was dominated by<1 mm particles,accounting for 70%of the total volume,and B5 treatment was dominated by<1 mm particles,accounting for 50%of the total volume.The bulk density of B5 treatment was 0.08 g/cm~3 higher than that of B2treatment,and the water holding porosity,field water capacity and saturated water content of B5 treatment were lower than those of B2 treatment.In the type of minimalist roof greening,the particles>1 mm in B3 treatment accounted for 70%of the total volume,and the particles>1 mm in B6 treatment accounted for 50%of the total volume.The bulk density of B6 treatment was 0.03 g/cm~3 larger than that of B4treatment,the aeration porosity and saturated water content were larger,and the water holding porosity and field water capacity were smaller.The treatment of structural materials(fly ash)has better performance in maintaining the height of the substrate.Under the same impact of rainwater environment,the settlement height of B1,B2 and B3with x-matrix was 3.2 cm,2.3 cm and 0.5cm higher than that of B4,B5 and B6 with fly ash,respectively.Comprehensive analysis of the landscape effect,the best formula for the minimalist roof landscape simulation is B3(X matrix:1～2 mm fly ash:0.063～1 mm fly ash:<0.063 mm fly ash=50:1:36.5:12.5),the best formula for the simple roof landscape simulation is B1(X matrix:2-4 mm fly ash:1-2 mm fly ash:0.063-1 mm fly ash:<0.063 mm fly ash=50:9:12.5:16:12.5),and the best formula for the garden landscape simulation is B5(1～2 mm Peat:4～6 mm fly ash:2～4 mm fly ash:1～2 mm fly ash:0.063～1 mm fly ash:<0.063 mm fly ash=9:3.64:17.29:17.11:26.31:26.71).4.In the cultivation experiment of virus-free mini potato seedlings,the yield per plant of potato was analyzed.Under P3 density(13.5 cm×13.5 cm),the yield per plant of TD-D treatment was the highest,which was 10.91 g/plant,higher than that of vermiculite substrate under the same conditions,which was6.51 g/plant.According to the range analysis of particle size of each treatment,the proportion of fly ash with 1～2 mm particle size is between 0%～14%,the proportion of fly ash with 0.25～1 mm particle size is between 40%～65%,and the proportion of fly ash with<0.25 mm particle size is between 20%～35%.5.The particle size of fly ash is the main factor affecting the yield of seed potato in the experiment of original seed matrix cultivation of mini potato.The potato yield of yy4 treatment was the highest(17.25g/plant),which was 9.12 g/plant higher than that of pure vermiculite substrate under the same conditions.According to the results of orthogonal test,the proportion of 0.25～1 mm fly ash is between 50%～65%,the proportion of<0.25 mm fly ash is between 15%～37.5%,and the proportion of vermiculite is between12.5%～20%.6.The contents of heavy metals(Cu,Zn,Ni,As,CD,Pb,Cr,Hg)in fly ash samples were determined.The results showed that all the indexes met the soil environmental standards for heavy metals(GB 15618-1995);Through the cost accounting of the matrix formula containing fly ash selected in this study,it is found that the cost of the matrix with fly ash as the main component is lower,and it has a larger profit margin for the matrix manufacturers.The results showed that the water vapor balance and plant growth were affected by the mechanical composition of the substrate.In modern matrix blending process,it is very important to separate the particle size of matrix materials.Fly ash is used to produce new matrix,which can realize the resource utilization of fly ash and has economic benefits. |
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