referring to fig1 a soil retainer 10 is shown in perspective . soil retainer 10 is formed of an elongated flexible member 12 shown in elevation in fig5 . preferably the elongated flexible member is made of a material that is relatively long lasting in the environment . the material should have the properties of being flexible as it is envisioned as being formed in the shape shown in fig1 from a flat shape as shown in fig5 . further , it should not be susceptible to degradation by ultraviolet radiation . finally , it should be relatively inert in relation to the natural chemicals found in soil and the chemicals utilized for fertilizer and insecticides . the material selected should be easily formed and be inexpensive . while the various metals might meet some of the above requirements , either the cost or the level of corrosion or both would rule out such use . accordingly , the most desirable material would be one of the man made polymers such as polyethylene , polypropylene or a polycarbonate . it is recognized that many of the compositions coming from these plastic groups would not have all the properties listed above , however , generally speaking all of such properties can be found in some of these plastics . the retainer is preferably molded . referring now to fig5 the soil retainer is formed in a particular shape . namely the soil retainer should have a straight upper edge 14 and an arcuate lower edge 16 . formed at each end of the elongated member 12 are sockets 18 . sockets 18 , as best seen in fig3 are formed with a bore 20 adapted to receive a spike 22 . as can be seen from fig3 bore 20 has a length at least equal to the height of the retainer at the position of the socket 18 . spike 22 forms an important part of the invention in that it holds the soil retainer on the hill . the spike itself should be as close to nonbiodegradable as possible . it has been found that fiberglass rods are appropriate for this purpose . fiberglass rods are somewhat flexible yet sufficiently rigid so that they may be driven into the ground in the manner of a metal stake . fiberglass has a high resistance to degradation by soils and chemicals and the like and is relatively light weight . the structure described herein is formed for a representative slope of one foot rise for every two feet of run . this is shown in fig4 with the retainer installed in the bank . in order to attain the proper dimensions , it has been found appropriate that the height h should be approximately one fourth of the length l as shown in fig5 . the radius of the arcuate lower edge 16 should be approximately two thirds of the length l of the sector of the circle which is represented by the flexible member shown in fig5 . these dimensions will provide a soil retainer adequate to perform on a slope having a rise to run ratio of one to two . for a retainer on a bank having a rise to run ratio of one to one the height h should be approximately one third of the length l as shown in fig5 . the dimension of the curved form of the soil retainer 10 as shown in fig3 is important , as it determines the size of the eventual planting area 24 ( see fig1 ) that will be available for eventual use . referring again to fig3 the radius of the circle formed by the retaining member is approximately one third the length of the unformed retaining member as shown in fig5 . in one embodiment of this structure for a one to two slope , the length l was set at 34 inches ( 86 . 36 cm ) while the height h was eight and one half inches ( 21 . 6 cm ). this gave a radius r of approximately 21 . 25 inches ( 53 . 97 cm ) and a planting radius l / 3 of roughly ten inches ( 25 . 4 cm ). if the rise to run ratio is one to one , for a 34 inch ( 86 . 36 cm ) long retainer giving a planting radius l / 3 of 10 inches ( 25 . 4 cm ), h should be about 11 . 33 inches ( 28 . 78 cm ) and the radius r should be about 18 . 4 inches ( 46 . 74 cm ). it has been found that the spike 22 is appropriately somewhat longer than the height h in order to properly anchor the device to the bank . finally , it may be appropriate to form the elongated flexible member 12 with a rib 28 on the straight upper edge 14 of the elongated flexible member . rib 28 is appropriate to give a certain degree of stiffness to the elongated flexible member when it is placed on a bank as shown in fig1 and 2 . it is pointed out that the rib 28 can not be too large as it could impede the bending of the flexible member when placing it on a bank . the sockets 18 as shown in fig3 may alternatively be formed in the manner shown in fig6 and 8 . in fig6 the socket 18 &# 39 ; is shown with bore 20 &# 39 ; to one side of the axis a of the elongated flexible member . both the socket 18 &# 39 ; and the preferred socket 18 may be formed at the time the structure is originally molded . as a second alternative a socket 18 &# 34 ; is shown in fig7 and 8 . the socket shown as 18 &# 34 ; also includes a bore - like aperture 20 &# 34 ;. socket 18 &# 34 ; is formed by folding back the end of the elongated flexible member and welding the end of the flexible member at a point 26 to form the bore 20 &# 34 ;. in this embodiment , the retainer can be cut from sheet material either with or without rib 28 . in order to properly utilize the flexible member on a bank , the first step is to score a trench 30 in the bank that will follow the bottom contour or the arcuate lower edge 16 when the structure is placed against the bank . this score or trench 30 is best shown in fig2 where the original ground line is represented by the numeral 32 . this step may be accomplished conveniently by forming the elongated flexible member 12 and forming it into a curve as shown in fig3 . in order to accomplish this step , one may use a string or the like , such as string 34 that has fixed at one end an eye 36 and at the other end a hook 38 . by inserting the spikes 22 into the bores 20 , this looped string will then hold the elongated flexible member in its arcuate shape as shown in fig3 . as can be ascertained from fig3 string 43 is 4 / 3l in length . when l is 34 inches , ( 86 . 36 cm ) string 34 is 45 . 33 inches ( 115 . 15 cm ). the elongated flexible member may then be placed against the bank and a line scratched on the bank . the flexible member 12 is removed and the score 30 conveniently formed with a pick or the like in the bank . once this is accomplished the flexible member 12 may be placed in the scored trench 30 and the spikes 22 driven into the ground with a hammer or sledge . once the elongated flexible member 12 is anchored in this manner to the bank , then the string 34 may be removed and used with the next flexible member . referring now to fig2 a pit or a hole 40 can be formed behind the flexible member 10 with at least some of the dirt thrown up against the elongated flexible member 12 on the downhill side of the bank to form a berm 42 around the perimeter of the elongated flexible member 12 . the plant 44 may then be placed in the hole 40 and planting material 46 added to the hole as appropriate . the berm 42 should extend above the level 48 of the planting material 46 so that when the plant 44 is watered , a reservoir is formed within the perimeter of the berm 42 and water is not permitted to run down adjacent the edge of the elongated flexible member and be lost from the planting hole 40 . in clay soils , it may be appropriate for the hole 40 to be dug so that appropriate drainage from the hole will occur after watering of the plant . this , in some instances , may include utilization of the score line 30 , however this is not necessary in soil where drainage is adequate . while this invention has been described with a particular embodiment in mind , it should be clear that the invention is limited only as indicated in the claims which are appended hereto .
an elongated member having one arcuate shaped edge and on the opposite side a straight edge may be used to plant vegetative matter on a bank or hill . the elongated member is curved into a semi - circle and held in place by spikes so that a planting hole may be formed on the uphill side thereof .