2002年5月よりほぼ1，2週間置きに，沖縄本島名護市大浦のマングローブ林床内にあるアナジャコの巣穴口から水を採取し，水温・塩分濃度・水位・採取水量・幼虫令期および個体数などを調べた．穴の水は汽水で，水位（巣穴口から地下までの距離）は潮の干満によって上下し，最長250cm，平均144cmであった．穴口はアナジャコによって不定期に泥の蓋で開閉されるが開閉の有無にかかわらず，水が採取できた穴の81％で幼虫を確認した．現時点では季節による著しい個体数変動や令期の偏りはみられなかった．また長期間閉口している穴にも幼虫がいることは，巣穴坑道が地中で他の開口穴と続いており，成虫の出入りを可能にしているためと考える．以上の結果から本種はアナジャコが常に巣房を手入れし，は干上がることなく，有機物に富む安定した発生源を，独占的かつ有効に利用していると考えられる．冬季の発生消長は今後の継続調査で明らかにしたい．

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結果の検討は刈取り期の調査結果と合わせて行いたいのでここでは省略し, 簡単な要約だけにとどめる。
(1) 平均水深2～3cmの地表残留水があり, この残留水は小さなで最高水深は5cmをこえる。この地表残留水の生成は微地形と密接な関係にある。
(2) この残留水がなくなるには長い日数を要し, その減少は蒸発散のみによって行われていると見て差し支えない。
(3) この地表残留水の違いのために田面の乾燥には格差が生じる。従って地表の微地形が田面の乾燥に与える影響は大きい。
(4) 浸透能の調査結果によると地下浸透はない。
以下, この大区画無暗キヨ田においては, 中干し期の落水に関する排水仮説～ 地下排水は少なく地表排水の良否が田面の排水に大きな影響を与える～ は正しいことがわかった。

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Harvest time drainage in large paddy fields reported in the second report was investigated. In these fields drainage was begun a month before harvesting by taking out a board in an outlet to a drainage canal.
Surface water conditions in paddy fields changed as shown in Fig. 2 and 3. Subsurface drainage discharge was little the same as mid-summer drainage due to poor permeabilities of puddled surface soil and subsoil.
Cracks formed by mid-summer drainage on the surface had not remained. They vanished during water flooding period after mid-summer drainage (Fig. 9), and so were not useful for drainage. Large puddles remained after the surface run-off and soil dried very slowly (Fig. 6).
Surface drainage depends on evenness and inclination of the surface. In these large paddy fields, the difference of height of the surface attains to 10cm, so surface drainage becomes poor. After surface drainage fields dry by evapotranspiration. Compared with evapotranspiration, subsurface drainage discharge is little. In places which dried well in mid-summer drainage, soil rapidly dried in this time due to high bulk density caused by mid-summer drainage. This effect may be named as pre-drying effect and mid-summer drainage is useful for rapid drying in harvest time drainage.

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Mid-summer and harvest time drainage in small paddy fields having underdrains was investigated (Fig. 1). Many parts of the ground surface were always wet during the period of mid-summer drainage (Fig. 5) because both amount and frequency of precipitation were heavy (Table 3) during this period. Surface water was even impounded in small shallow depressions on the ground surface above underdrains or near open ditches. Tracer (white paint) did not enter the subsoil from the ground surface.(Fig. 8) Infiltration capacity and permeability of soil were small.(Table 2-1) It results from these test and observation that drainage in clayey paddy fields is not improved only by underdrainage using tile drains or open ditches.
During the period of harvest time drainage, there was no precipitation. The ground surface of the fields No.1 and No.4 dried up, but on the ground surface of the fields No.2 and No.3 the impounded water remained.(Fig. 10) The Field No.2 had large shallow depressions (Fig. 11) and the field No.3 had not been undergone mid-summer drainage. It is clear from these observations that in the case where a field has unfavourable topographic features for surface drainage or has not been undergone mid-summer drainage, even though it has underdrains, drainage can not be accomplished. It is because of the fact that flow of water through subsoil towards tile drains is restrained by the puddled layer being poor permeable. If this impermeable layer gets many cracks to become permeable, surface water flows through the cracks towards tile drains from the ground surface (Fig. 8). But if the ground surface is not dried, this layer can not have the cracks. Therefore, in the first place surface drainage is required.
At the end of this report, water balance is shown in one paddy field during the period of harvest time. We tried to estimate the process of drainage of fields in the case where precipitation frequently occurs and got good identity of estimation and observation (Fig. 14).

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これまでも理科学習の中で，思考を促す道具の１つとして描画法が取り組まれてきた。本実践では，理科学習用アニメーション作製支援ソフトウェア「Galop」を活用した小学生による概念学習において，児童にどのような影響を与えるのかを調べるとともに，授業での活用を図るための操作面・機能面の改善点を調べることにした。

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The authors reported on the annual variation of bearing capacity in heavy clayey paddies. This paper is the succeeding report of the studies on the bearing capacity of the paddies, therefore the method and treatments are same as that of previous report. The bearing capacity after drainage arises sporadically in places of a paddy field. The plain distribution of bearing capacity in paddies is shown in Table 1. The fact that the bearing capacity at the depth of 0-5 cm or 5-15 cm is 0.2-2.0 kg/cm² at the end of mid-summer drainage, and shows very large scattering of values. This does not appear to be caused only by drainage. The bearing capacity appears largely, at the time when the surface of paddy field is cracked in the process of drying, but the deeper the layer is, the more the relation between the bearing capacity and the state of drainage on paddy is lessened (Fig. 2). This may be connected to the forming of the compaction layer due to ploughing. No difference is find in the appearent condition of paddy surface, between the mid-summer drainage and the drainage for harvesting, but at well drained place, the type of increment of the bearing capacity is rather larger than 0that of mid-summer drainage time. As is shown in the relation between moisture content and the bearing capacity (Fig. 3), moisture content of 70-50% becomes the critical point of cracking from where the bearing capacity becomes large. But it is difficult to guess the bearing capacity by the water content.
As mentioned above, mid-summer drainage may contribute to the increment of bearing capacity owing to drainage for harvesting, except the place undrained in mid-summer (Table 2), that is, the bearing capacity over 1 kg/cm² can be expected within 2 days after drainage for harvesting, while in the case of midsummer drainage, it takes 5-6 days. But no effects is found at the place where the bearing capacity did not grow up more than 0.6 kg/cm² in mid-summer. The critical moisture for cracking in drainage for harvesting is not so different from the one in mid-summer, and the bearing capacity is much lower at the place where drying proceeded so as to make cracks in mid-summer, than at the place where no crack arised.
The measurement of bearing capacity is necessary for the use of land-vehicle. And it is very important that the water drainage controlls the bearing capacity for the employment of vehicle in good condition. Therefore, in these points of view, the results are summarized as follows.
(1) The bearing capacity of the surface of clayey paddy field is controlled by the drainage condition, especially by the rate of the surface drainage and the weather in a season.
(2) The bearing capacity of clayey paddy is guessed from the state of puddles after the drainage, which depends on the gradual slope to catch drain and flatness of the paddy field.
(3) The mid-summer drainage may be very effective to get the bearing capacity for employing land vehicle more quickly after drainage for harvesting.

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