施 肥 法

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The 　Crop 　Soienoe 　Sooiety 　^of 　Japan

北陸作物学会報31：66〜69q996）

施 肥 法

^の

違

^い

^が 地 下 浸 透 水

^の

量 と硝 酸 態 窒 素

^の

　　　　　　　 リ

^ー

チ

ン

グ ^に 及 ぼ す 影響

　 鯨 　幸 夫^1），田中桂

T

^{−1・i，杭田忠三2）}

（o 金沢大 学 教 育 学 部，^{2）石 川ス ズエ 販}売 （株）^）

Effects

　of　

Different

　N −Fertilizer　Applications　on

Drainage



Water 　　　　　　 Quantity

^andNitrate−Nitrogen　Leaching

　

^{Yukio　KUJIRAI ），Keiko　TANAKAD 　and 　Cyuzo　KUIDA2 ）}

（^1＞Facultyof　Education，KanazawaUniversity．Kanazawa 920 −_ll，

z_〕IshikawaSuzueDistributionCo ．Ltd．，^Kanazawa920−03）

要 旨 ^：作 物^を生 産する過程^で施^{用 さ れ る}窒 素^肥料^が地 下^に浸 透 ^し，地 下 水 汚 染^の原 因と な^{っ てい る}事 例

が数 多 く報 告さ れ^て い る．水 稲栽培^は，^畑作^や野 菜 栽 培^{お よ び}畜^産等^と比 較 ^して ，硝 酸 態 窒 素^{の リ}ー_チ

ング は少^{ない とさ れてい る}，し か し，施 肥 法^の違^い や栽 培 する水 稲 品種^の 根系^{形 態の} 違^{い に よっ てリ}ー

チ ン グ^に 差 異 が ある か ど うか につ い ての 報 告^は少^ない ．本 研 究^{で は}，施肥法^の 違^{い と}根 系形態^の 違^い が 土壌^浸透水^{の量 と}硝 酸 態 窒 素^{の リ}ー_{チ ン グ にどの ような影 響を及ぼす か につ いて検}討^{す る た め}，^{コ ンテ}

ナー_{を用い た栽 培 実験 を行っ た}．また，^硫酸^{カ ル シ ウム の}施 用 効果^{につ い て も}検討 ^{し た}．施 肥法^は， 表 層 施肥 （表層10cm ） と深^層施^肥 （10− 20cm）^とし，品 種^は，農 林 3号 （根 系 開度^が 小^さい）^と陸羽132 号

（根 系 開度^が大 き^い ）^を用^い た．浸 透 水量 は深^層施^{肥 区に比べ て}表 層 施^肥区^で大^{き く}， 農 林 3号^{に お い}

て この 差が 顕著であ 1_）　1 登熟 期^{に お ける}毎 分^{あた りの}平 均 浸 透 水 量^は，表 層 施肥区^で

301

．5ml ^で あ る

の に対 し_， 深 層 施 肥 区^で は 55．3ml ^で あ^っ た．ま た，硫 酸^{カル シ ウム の}施 用^{に よ} り浸 透 水 量^が増 加す^る 傾 向が認め ら れ た．硝 酸 態 窒 素^{の リ}ー_{チ ン グはい ずれの 処理区に おい て も小さ}

く，水 稲 栽 培^は地下水 汚 染^に関 して は影 響が 少 な^い と考^{え ら れる}．し か し，根 系 形 態^の違^{い や}硫 酸^{カル シ ウム の} 施用効果^{の メ カ}

ニ ズム に関して は，更に検討^{す る 必}要^{が あ る}，

Abstract ^： Two 　different　genotypic^varietiesin　rice 　^{（Oryza　sativa 　L}．_）．Norin　3　which 　shows 　a　sma11 spread 　of　roo し systems ，^andRikuul32which 　shows 　alargespread ofrootsys しems ，^{were 　used 　ullder} two　different　fertilizer　applications _，　surface 　application 　and 　fertilizer　application 　to　deeper　layer　with two 　replications ，　 Application^{rate 　of　mined}gypsum ineach treatmentisO ，100 ，200^and400kgha−₁

，

respectively ．　In　thisstudy ，we 　used 　plastic^eontainers （32cmx　42cmx　25cmindepth_）with 　six　plants perbox　togrow^ricein　the　greenhouse ，Nitrate−nitrogen 　leaching　were 　measured 　every 　two　weeks 　dur． ing　the　experimental 　period．　Drainage 　water 　quantityper^{minute 　was 　shown}301 ，5ml　min ’₁

　insurface applieation 　and 　55．3　ml 　min −_l

　in　thc　othcr 　treatment ．　The ^¢hanges　of　nitrate −_{nitrogen 　leaching}during the　growthperiod^showcdthe　different　patterns^amongthe　different　N −fertilizer　applications ．

キー_ワー_{ド：根 系}

， 硝 酸 態 窒 素， 浸透

Key　words ：Leaching，　Nitrate−nitrogen ，Root　system

　Nitrogen　is　essential　to　growth ^anddevclopment 　Qf　crop 　plant．　Many 　farmers　have　used　many 　kindof

N −fertilizers　increasing　to　make 　croP 　productionprofitable．

　On　the　other 　hand ，50percent^orless　ofthisfertilizer　isactually used bythecropinagivenyear ．The

remainder 　either 　leaches　out 　of　the　soil　to　ground −_water ，^washesoff ，evaporates ordissolvesinwater in the　process^calleddenitrification，　or　stays　in　the　soil　where 　it　may 　be　useful 　for　later　crops ．　In　case 　of

Japan ，^nitrate −_nitr

 gen　^！eachingis　one 　of　the　most 　important　problems  thataffectthe environment 、 Nitrate−nitrogen 　leaching　Qf　thepaddy ^ricefield　in

Japan

^{tend　to　be　lower　than　those　case 　of　normal 　soil}

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fielcl,tea field,livestockfarmingetal.

Nitrate-nitrogen leaching inpaddy ^{rice fieldis under 2.0 mg e}'1

as a mean valuei･2} ,In this study, we carried out the model experiment todetermine^the nitrateJnitrogen leachingand drainagewater quantity per ^minute from the soii using differentgenotypie ^{rice cultivars,} Norin 3 and Ruikuu 132.

Materialsand Methods

^{This experiment was carried out} ina greenhouse from

June

^{toDecember in1992.}

Different

genotypic ^cul- tivarsNorin 3with a small spread of root systems and Rikuu ^{132 with} a largespread of it^3･4i ,were used under two differentfertMzer applieations. Fertilizerof soil surface applieation treatment isamong the soil

layer fromsurface to10cm insoil clepth,on the other hand, fertilizerapplication to deeperlayertreat-

ment isthe layer from 10to20 cm in the soil

<Fig.1).

^{Four levelsef mined} gypsurn, O, ]eO, 200 and 400 kg ha'iwas applied inthesandy loam soil containing O.3gN, P20sand K20 per ^soil

Ckg)

^, respectively.

6

plantsper plastic^{container box sized} 32 cm ^x 42 cm ^x 25 cm in depth were grown ^under the different

method of fertilizerapplications. Nitrate-nitrogenleachingwas

measured using Hach Digesdahl DigestionApparatussystem ev- A B

ery two wceks tillSeptember 20

(ripening

^{stage) .Stemnumber}

per p]ant ^and plant height were measured at every growth stages, and root dry weight per plant ^and yield^{at the} harvest

stage were investigated.

Fig.1 Differentmethed otfertilizerapplica- tions inthecontainer box.

A:Applicationtodeeper layer,

B:surtace appiication,

[2Z]^{:The area of slanted linemeans}

tertilizerzone inthe soil.

'

Table 1.Nitrate-nitrogenleaching from the lowerpositionofthecontainer boxof ^Norin

3.

Nitrate-nitrogenleaching G.vpsumapplication ^{Method of} fertilizerapplications

Surface application Ferti]izer

layer applieationte deeper

Aug. Sep. Oct. Aug. Sep.Oct.

52252919 ^52252919

O

(kg

^hr'")

100

200

400

ABABABABO.30 O.10 O.18 O.41 O.16 O.13 O.15 O.03 O.05 O.26 O.42 O.06 O.08 O.68

O,30

O.40 O.16 O.06 O.03 O,12 O.12 O,12 O.09 e.60 O.96 O.12 O,12 O.05 O.04 O.15 O.11 O,36 O.16 O.16 O,11 O.11 O.09 O,08 O.03 O.04

O.19 O O.95 O

O.14

^O

O.22 O O.12 O O.04 O O.08 O o.es o

.06 O.10 .11 O.04

.12 e.18

.18 e.06 .08 O.17

.16 O.08

.07 O.19

,10 O.04

O,18 O.1]

O,05 O,07 O.32 O 05 O.03 O 03 O.34o.o3

o.e4 O.20O.20

O.06 1)2)3)A,B: upper position and lower position of the container

The value means N03'N mg e'i

, respectively.

N, P20/)and K20:^O.3 g/kg

(soil)

, respectively.

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Table 2.Nitrate-nitrogenleaching

132

^under the ditterentN-trom

the lower position tertilizerapplications.of

container boxot Rikuu

Nitrate'nitrogenleaching Gypsumapplication Methodof fertilizerapplieations

Surfaceapplication Fertilizer

laycr application tocleeper

Aug･ Sep- Oct. Aug. Sep. Oct.

52252919 52252919

O

(kg

100

200

400

hr-1)ABABABABO,32 O.12 O.

0.39 0,13 O.

O.26 O.10 O.

o.4o o.os e.

O.38 O.08 O.

O.16 O.14 O.

O.19 O,06 O, O.16 O.13 O.

eg11290218040802oooooooo.23 O.l6 .09 O.07 .24 O.18 .03 O.09 ,02 O.04

.19

O,04

.11 O.08 .03 O.04

O.12 O.06 1.76 O.10 O.16 O.12 1.98 O.10 0,14 O.08

1.32 O.10

O.10 O.06 2.79 O.12

O.08 O.15 O.03 O.03 O.03 O.03 O.16 O,26 O.29 O.03 O.02 O,08 O.18 O.32 O.04

O,02 O.03 O.05

O.11 O.28 O.23 O.02 O.03 O.05 1)

2)

A and B mean the sampling position ^of

upper position ^and B islowerposition.

Each value means N03-N leachinglevel

drainage water from the

(mg

^e'i).

contamer box,^{A is}

Resultsand Discussion

The values of nitrate-nitrogen leaching of both Norin 3 and Rikuu 132 in the surface fertilizerapplica- tiontreatment werc lessthan 1.0 mge 'i,

on the other hand, those in the fertilizerapplication todeeper layertreatment inRikuu 132 on August 5 were more than 1,O mge 'i

(Table

^{1, 2),}Nitrate-nitrogen leaehinginfertilizerapplication todeeper layerwas largerthan that in surface fertilizerapplication. The changes ef nitrogen leaching during the rice growth period ^{showed the} differentpatterns ^{among the} diffe- rent mcthod of fertilizerapplications. However, the values of nitrogen leaching werc lessthan

3,O

^mg e'1 in this model experiments. Paddy rice fieldis suggested to be one of the good land for sustainable agrieulture.

Quantity

^{of drainagewater insurface fertilizer}application was larger than that of fertilizerapplication todceperlayerinNorin

3

and Rikuu 132,and itwas shown inclear tenclency inNorin 3

(Fig,

^2,3).

There was highlynegative correlation coefficient between root dry weight and the volume of drainage

water from the soil in the surface application treatment at the harveststage, on the other hand, itshowed

the positivecorrelation coefficient inthefertilizerapplication todeeperiayertreatment

(Table

^3).

^{The effects of mined gypsum on crop growth were reported as a review} by Shainberget al,5) Applica-

tion of mined gypsum hastened the water leachinginthe soil. Gypsum applieation inthe damp _ground

would be effeetive for drying the soil, on the other hand, itis not clear about the affect of the

nitrate-nitrogen leaching inthis experiments. The effects of genotypic differences as the spread of root systems on nitrogen leachingwas recognized, but itneed further experiments to analyze the results in

rnore details,

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ELt?･a･aslztnlfLTx2ttieg=

se,ooo

le,oeo

5,OOO

1,OOO

500

100

Fig. 2

o so leo

^T[ME (min)

The quantityctwater leaching from posjtion^ot thecontainer box ci^Rikuu thedifferentlevelof mined gypsum.

2v･T

'N: E9

g

g,'

t e

2･

Jw

150

the lower 132under

50,OOO

10,OOO

5.000

1.000

500

Fig.

100

3

o se loo

TIME (niin.) The quantityofwater leaching ^{from the}

position^{ofthecontainer} boxof Norin3.

150

1crwer

Table3. Relationshipbetween

from the container boxroot

dryweight

per

-

plant^and waterleachingper minute

Applicationmethod CultivarRegression Surface application

Fertilizerapplication

todeeperIayer

Norin 3Rikuu 132 Norin3Rikuu

132

y='16.26x y=-11.21x y= 13.81x y= 5.41x

+ 905.73 + 444,08 - l60.09 - 71.21

r='Or=-Or=

Or=

O

.,..890(p <O 26o(p>o

860(p ^<O

823(p

^<O

.05).05).05).05)

y:^the quantity ^of grainage ^water from thelowerposition^{of container} box

^{x: root dry weight} per plant

<g

plant']) References

1) AichiAgriculturalExperimental Station1990. Reportof Environmental Preservation, 2)Hidaka S.^1992. Quarterly^{Report, Fertilizer1:37'39,}

3) KujiraY. 1987.Jpn,J.CrepSci.⁵⁶

(Ex,2):59L60.

4) KujiraY. 1992.Abstractsof lstICSC^/72.

5) Sha{nberg I.etal, 1989. Advances inSoilSci.9:1-119.

(ml

677

mm

!20.

-1)

,

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