Research About The Effects Of Soil Water And Heat Transfer And Maize Growth Characteristics Under Mulched Drip Irrigation

The shortage of water resources is the most important problem in the agricultural production in the north of China.How to realize the coordinated development of agricultural production and water saving technology is an important challenge for agricultural management.The field experiment of drip irrigation and drip irrigation under mulch of maize were carried out,in which drip irrigation under mulch(shortening F)and drip irrigation(shortening W)and 5 drip irrigation quantity were designed including 0(shortening D1),80(shortening D2),120(shortening D3)160(shortening D4)and 200(shortening D5),and those problems were observed and analysed,including soil water movement,heat transfer in soil,the growth of spring maize,spring maize root distribution and spring maize yield and water use efficiency,and the HYDRUS numerical simulations were compared with the measured results.The main research contents and conclusions are as follows:(1)During the whole growth period,the average soil water content increased with the increase of drip irrigation quantity,FD5 and WD5 are the largest soil water content.The near crop root zone soil water can be significantly improved before the big trumpet period,increasing with the increase of irrigation quantity,which played a key role for drought resistance.The average soil water content increased with the increase of drip irrigation quantity after 3 days of drip irrigation,FD5 > FD4 > FD3 > FD2 > FD1,WD5 > WD4 > WD3 > WD2 > WD1.The increasing amplitudes were max at the end of the drip irrigation,the soil moisture content tended to be consistent after 3 days.The changes of soil water content were obvious at 0~20cm soil layer,and gentle gradually at 20~40cm and 40~60cm soil layer.The change of soil water content was in the 40 cm soil layer under the condition of drip irrigation,which was the main absorbent layer of maize root system.(2)During the whole growth period,the average soil temperature near the root zone decreased slightly with the increase of drip irrigation,The variations of soil temperature were FD5 <FD4 <FD3 <FD2<FD1,WD5 <WD4 <WD3 <WD2 <WD1.The average soil temperature of mulch treatments was higher than that without mulching treatments in the whole growth period.(3)The growth period condition of maize,including plant height,leaf number,leaf area per plant and leaf area index,was a single peak curve in the whole growth period.The height of mulching drip irrigation were apparently higher than that of drip irrigation in the early stage,including seedling stage,jointing stage,booting stage,but the difference was not obvious after the grain filling period.The leaf numbers,leaf area per plant and leaf area index of mulching drip irrigation were significantly higher than those of drip irrigation at jointing stage,trumpet stage and filling stage,and reached to the maximum at the time of milking.(4)The root characteristic parameters of corn included root length,root diameter,root surface area,root volume,root tip number and root dry weight,which were increased with the increasing of drip irrigation,FD5 > FD4 > FD3 > FD2 > FD1,WD5 > WD4 > WD3 > WD2 > WD1.Under the same drip irrigation,the root length and root tip number in the different diameter class of drip irrigation and film mulch drip irrigation showed that fine root(diameter <0.5 mm)> medium root(0.5-1.5 mm)> thick root(diameter >1.5 mm).On the contrary,the root surface area and root volume in different diameter class of drip irrigation and film mulch drip irrigation showed that thick roots(diameter >1.5 mm)> medium root(0.5-1.5 mm)> fine root(diameter < 0.5 mm).The vertical distribution characteristics of maize root length,in the depth range of 0-40 cm,the root length distribution of all drip irrigation was in accord with the "?" type distribution,and the root length at10~20 cm was the largest,accounting for about 49-67% of the total root length.The vertical distribution characteristics of root dry weight,in the depth range of 0-40 cm,the root weight distribution was in the "T" type distribution,and the root weight at 0~20 cm was the largest,accounting for about 70-90% of the total root weight.This would not only help to increase the lodging resistance of plants,but also to absorb water and nutrients in different soil layers.(5)The maize biomass constitutes including ear length,ear diameter,ear weight,number of rows,kernels per row,ear weight,ear diameter increased with the increase of drip irrigation.The bald tip length and hundred kernel weight decreased with the increase of drip irrigation.The maize yield and water use efficiency increased with the increase of drip irrigation.The indexes of maize biomass by Pearson correlation analysis showed that the quantity of drip irrigation had a great influence on the biomass of maize,and was positive correlation,but the film mulching had little effect on the biomass of maize,and showed negative correlation,which indicated that the film mulching had the effect of blocking the water transmission,and it was not conducive to the absorption of soil water when rain was large.The total yield increased with the increase of drip irrigation quantity,and accounted to the highest when the quantity of drip irrigation was 160 and 200 m3/hm2,but there was no significant difference between two treatments.So the 160 m3/hm2 irrigation quantity was suggested to the best quantity of film mulch drip irrigation and drip irrigation.(6)The soil water and heat transfer of film mulch treatments and non-film treatments were simulated respectively in the whole growth period,typical drip irrigation and typical rainfall.The conclusion was drawn that the change rule of the simulation was consistent with the actual change,which can reflect the process of soil water and heat transfer.The simulation results showed that the simulation results of short time were better than that of the whole growth period,and the simulation results of soil water content are better than that of soil temperature.