Laboratory of Plant Husbandry
December 12, 1961
Faculty of Agriculture at Kyushu University, Japan
sponsored by: Mitsui Mining and Smelting Company, Ltd
INTRODUCTION AND SUMMARY
Following course construction, golf course turf (especially putting greens) are effected by nature through rainfall and trampling by golfer's walking and by rolling of mowers. Consequently, golf course soil is hardened by degrees and air and water permeability are reduced. Turf in golf course greens is closely and frequently mowed and trampled. As a result, its growth is abnormal and in extreme cases, it can be withered. Golf course greens turf has a short life.
On golf courses, a number of treatments are used to maintain or renovate greens. Procedures often used are: 1) Turf is stripped off, underlying soil is plowed or turned over to improve its physical properties and finally, the area is resodded. 2) Boring or line-cutting is also performed on turf by special machines. However, these treatments require a great deal of labor, time and expense.
It is desirable that greens be maintained in optimum condition for playing. This is a major concern of greens keepers of golf courses. The short life of turf on greens has an important relationship to the operating cost of golf courses.
Tests have been conducted in the past with soil amendments such as horticultural perlite and others that are applied to prevent soil from hardening. These prior studies did not clarify the effect of these materials. Accordingly, this research has been done to determine the effect of perlite application on improvement of golf course greens.
MATERIALS AND METHODS
"Koraishtha" (Zoysia Tenuif olia Wilid) is one variety of sod used for greens in many areas of Japan.
An experimental field of 1.64 acres was provided in "Koga" golf link located in a suburb of Fukuoka City, Kyushu island. Soil texture of the experimental field is as follows: Surface soil is reddish loam subjected to soil dressing of 20 to 25cm in depth. Subsoil is composed entirely of sand.
Seven experimental plots were designed to test the effect of horticultural perlite and other soil conditioners:
A standard amount of fertilizer was applied to both the "Cririum" plot and the "Soiluck" plot.
In order to clarify the influence of trampling, each of seven plots was divided into "trampled" and "non-trampled" blocks.
Tests were conducted three times to make them statistically sound and the plots were randomly arranged according to the "Randomized block arrangement." A unit plot was an oblong area 2m X 0.8m and the distance from plot to plot was 0.5m.
The experimental field was plowed and prepared on March 28, 1960. On the same day, horticultural perlite and other soil conditioners, with fertilizers, were applied according to the prescribed design, and the areas were sodded in the usual manner.
Top dressing of 37.5 kg of N, 26.2 kg of P, and 26.2 kg of K20 in the forms of urea, fused phosphate and potassium chloride, respectively, was applied in five different applications during the growing period.
Turf management including irrigation and weeding was appropriately performed. In 1960, management was done in the same manner as the year before. In 1961, trampling was done on all the trampled plots by ten persons, once a day except rainy days, during the period from March 1st to October 31st.
In order to obtain and to analyze the results, the following were observed:
RESULTS AND DISCUSSION
In 1960, only the yields of the top mowed were surveyed. As the trampling treatment had just begun, all plots were regarded as non- trampled ones. The effect of material application on the yields of the top was estimated by analyzing the differences among plots with "analysis of variance." The difference between plots was not significant, and the effect of the application perlite and other soil conditioners on the yields of the top could not be recognized.
Yield of Top
The results obtained in 1961 will be described below. The yields of the top mowed are shown in Table 1. According to the results of "analysis of variance" for the differences in the yields of the top mowed between plots, it was found that, in non-trampled blocks, the differences among seven kinds of treatment were not significant so that the application of perlite and other soil conditioners was ineffective.
In trampled blocks, the differences among plots were significant however. The difference in the yields between perlite plots (except perlite small particles - 1.0cm) and control were distinctly recognized. Specifically, three plots of perlite (large particles) - 3.3 cm, perlite (large particles) - 1.0cm and perlite (small particles) - 3.3cm were much higher than in the control plot. The difference in the yield between perlite (small particles) - 1.0 cm plot, "Cririuin" plot or "Soiluck" plot and control was not significant.
The yields of the top among plots in trampled blocks are compared in Table 2. Comparing yields between control plots in both trampled blocks and non-trampled blocks (see Table 1), trampled plots had a much lower yield than non-trampled plots. Trampled soil has a much lower yield than untrampled soil. Plots treated with perlite (except perlite (small particles - 1.0 cm) had significant differences in yield as compared with the control plots. The yield of the control plot in trampled blocks was very low as compared with that of control plots in non-trampled blocks. Even if perlite or other soil conditioners were applied, yield in trampled blocks was somewhat lower than non-trampled blocks. In consideration of above-mentioned facts, it may be said that the application of perlite is effective in improving growth of turf subject to traffic compaction.
Root Development
The yields of the subterranean part, which were dug up and surveyed, are shown in Table 3. In trampled blocks, the yields of the top were related to those of the subterranean part as shown in Figure 1.
In Figure 2, the state of the root development of plots in trampled blocks is presented. Root development was good in three perlite plots of - perlite (large particles) - 3.3cm, perlite (large particles) - 1.0cm and perlite (small particles) - 3.3cm and was somewhat low in three plots of "Cririum", "Soiluck" and perlite (small particles) - 1.0cm. From these results, it is assumed that top growth such as leaves and stems is influenced by the development of root system. Especially, in control plots subjected to the unfavorable influence of trampling, the yield of the top is low.
Soil Hardness
The values of soil hardness, which were observed during the experimental period, are recorded in Table 4. In general, the observed values of soil hardness cumulatively increase with progressive traffic compaction.
Moreover, comparing trampled and non-trampled blocks, the soil hardness of the former is always higher than that of the latter. The values for soil hardness of perlite plots in trampled blocks is usually low as compared with that of control in trampled blocks and is equal to or sometimes less than that of control in non-trampled blocks.
From the above mentioned, it may be assumed that perlite works to reduce the solidification of soil compacted by trampling. Furthermore, in order to examine the relation between soil hardness and the yields of the top mowed, the correlation coefficient between these two kinds of values was calculated.
sigma=0.66 (d.f.=l2, significant at the 1% level)
sigma=-0.57.(d.f.=l2, significant at the 5% level)
sigma=-0.45 (d.f.=5, not significant)
sigma=-0.81 (d.f.=5, significant at the 5% level)
According to these analysis, soil hardness closely relates to yields except in the case of 3), this confirms the aforesaid assumption.
Thus, the application of perlite is effective in preventing the compaction of soil.>/b> However, the extent that the yields of the perlite plots in trampled blocks exceed those of control in the same block fluctuates with season (refer to Table 1). This is obvious in Table 5 that shows the seasonal change of the ratio in yields of perlite plots to control plots in trampled blocks.
Though the effect of perlite application was recorded during the experimental period, it was somewhat lower on August 9. In 1961,
there was dry weather during this period. In this connection, the total rainfall depth recorded in the experimental field during period from June to August was 299mm, which was much less than that for the same period during an average year (622mm). Therefore the effect of the perlite application may be influenced by rainfall depth, the frequency of rainy days and the available moisture content of soil which is not dependent on weather conditions. Moreover, the growth stage the turf is undergoing also has an effect.
In order to analyze these relations, the yield of the top per day (the value obtained by dividing the yield of the top mowed by the number of days spent from preceding mowing) and the ratio of rainy days (the value obtained by dividing the number of rainy days visited with the rainfall depth of 1mm or more per day by the number of days spent from preceding mowing) were calculated and illustrated in Figure 3. From this figure, it is learned that the development of the top such as leaves and stems closely relates to rainfall (soil moisture content).
Top growth was good only around August 9 during the dry weather period from June to the beginning of September. From June to the beginning of September, though, the rainfall depth was little, the rain uniformly came and the surface runoff ratio of rain water was little. Therefore, it is considered that soil moisture has been kept uniform and that moisture content hardly reached the wilting point. Consequently, lawn growth was relatively good without suffering from a drought.
Thus, the effect of the perlite application is low when the condition of soil moisture is good, whereas the effect is high when soil moisture is liable to be low as it was around August 9 (refer to Table 5 and Figure 3). Judging from these results, it is assumed that, in addition to reducing soil compaction, the application of perlite in trampled blocks may be somewhat effective in increasing the water holding ability of soil.
The test concerning water holding power of perlite was done in the Phytotron by the authors.
The results obtained in the wilting test which was done in order to ascertain the aforesaid assumption are given in Table 6. In the test, the different kinds of soil shown in the table were packed in aluminum pots 9cm in diameter and 9cm in height and the young seedlings were planted and cultivated with culture solution. After seedlings were completely rooted, the soils were saturated once with distilled water. Irrigation was then stopped, pots were allowed to stand in the greenhouse, and the number of days that it took for seedlings to wither was recorded.
As shown in Table 6 and Figure 4, the number of days to withering was longest in the case of 100% perlite and was shortened with the decrease of the mixing ratio of perlite and soil. Maximum water holding capacity for various kinds of soil are shown in Table 7. The capacity became less in the order of perlite, mixture of soil and perlite, mixture of sand and perlite.
(The picture above was taken after only 10 days with no water. On the right, the ryegrass grown in just sand and reddish loam soils had already wilted. Various mixes with perlite in the center did better, and grasses grown in 100% fine perlite on the left side of the picture did best.)
From the above results, it was determined that perlite has a high water-holding ability.
Air-and-Water-Permeability
The values for air-and water-permeability on December 3, 1961 are given in Table 8. In estimating these values, the following procedure was followed. In each testing plot, 20 ml of water was injected for five seconds into the soil at a depth of 8 cm. Secondly, the pressure required to inject water into soil as recorded and, finally, air-and water-permeability was calculated as a reciprocal of the readings of the test.
Results in the trampled blocks are remarkably lower than those in non-trampled blocks. Furthermore, in trampled blocks, permeability in control plots is lowest and is one third to half of that of plots containing perlite and other soil conditioners.
Thus, though air-and-water-permeability is reduced by trampling, this reduction is lessened by the application of perlite. From the relation between air-and-water-permeability and the yield mowed of lawn (refer to Tables 1 and 7), it is evident that the growth of turf is not influenced even if the permeability is somewhat reduced. Growth, however, is depressed if permeability is significantly reduced. Hence, the application of perlite reduces the deterioration in air-and water-permeability, so that the application is effective to the growth of lawns under traffic compaction.
SUMMARY
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Table 6: The Influence of the Kind of Soils on Wilting of Italian Ryegrass
Degree
of
WiltingSoils Tested
Reddish Loam
(Original)
Soil UsedSand
Horticultural Perlite
100% Large Particles Horticultural Perlite
100 %Small Particles Reddish Loam &
3.3 Large Horticultural Perlite Reddish Loam &
1.0 Large Horticultural Perlite Reddish Loam &
3.3 Small Horticultural Perlite Reddish Loam &
1.0 Small Horticultural Perlite
+
++
Permanentday
4
5
7 day
4
5
6 day
10
16
22 day
10
17
24 day
5
6
9 day
5
6
8 day
5
9
11 day
5
9
11
Withering
9
9
28
32
13
10
13
13
Table 7: Maximum Water Holding Capacity of the Soils Used
Soil
Reddish Loam
(Original)
Soil UsedSand
Horticultural Perlite
Large Particles Horticultural Perlite
Small Particles Reddish Loam &
Horticultural Perlite
Large Particles
(1:1) Reddish Loam &
Horticultural Perlite
Small Particles
(1:1) Sand &
Horticultural Perlite
Large Particles
(1:1)
Masimum
Water-Holding
Capacity 64.2
38.8
221.3
364.6
81.1
91.6
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