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» 34 » 1 ù j b îµ[ £TÂA¥ HLNPV 2 j4ñ¥ k ùW Ü b¾ÓW¹º A TµâD¥ð Ø a² a L P¨rT[ÉB¿É¥yp[ ù¹\ɵâ9à 7ù4 I b 1oM 9à 9 j jЧ©[25]æ¨ 3â ï 71ÐÈHD¥F eŵâNª ùî[26-30]9¨ ÈH 71E¾E¥ªÄ ÚÚ a î ÿS© a8l aÉ ³1È÷³1NìÅL¥ 3â ï 71ÈýD7 OY ¸ 3pY ÂÏ / b V[ Â Ï V[ A “ -µâ9Ã¥µâ»û òµªÄ9 µ1 üA¥ Ä bÇ £øE³1| £÷¿9 £ ¥/Z7 O ¸V9à £Ïn¥ b E9à £ bµâ,ÖÌE³1-¥îï7 Oµâ´ ¸ sÖÌ,¥Y b £øØâE a 6 £øE¥ 8 v bÈHDE³1È÷NìÅL¥ 3â ï 71ÈýDi O ¸p b¹ \ɵâ9Ã/ L¨Ä P ¤v ë P¨üj m 2c bVV 3Z U¥sTþ P¨²T A v HLNPV¥rT 1 z¥7 O[ £T¹ÂA¥rT »¬1z¿[ F²T¹ÂA b [ £TÂA¥ 5Q]Tþ k a55 ñâ ï]¥ HLNPV Ï PÉr 4 ñ ¥ KõkÏ HLNPVû Ü Àµ 3 £ ÄCÂA9 Àµ üAh ª ü[ £T¹ÂA H Éù Ü b V 3 HLNPV sTþµâ9à ¥ P¨ f Ø° Table 3 Application of HLNPV on some crops under negative pressure irrigation Tþ Crop ¹Ä Site 9à HWIrrigation duration HLNPVâ ï Pressure and number of HLNPV ÂA Cover liquidHLNPV HLNPV running state lâ É ì 2014-12-27À 2015-02-26 5 a7.5 a10 kPaò 6ñ F ² z F ²í üAh ² 6 2 2014-06-13À 08-10 5 a10 a15 a20 kPaò 4ñ F ² z F ²í üAh Û Ø 2014-08-29À 10-30 5 a10 a15 a20 kPaò 4ñ F ² 5 kPa 25 j30 d £M a 45 j50 d äæÎ µj ð5 10 kPa 45 j50 d £MB° eâ 15 a20 kPa¥ z blâ É ì 2015-11-07À 2016-01-23 5 a10 a15 kPaò 6ñ F ² z F ²í üAh oÅ ¡ 6 2 2015-05-05À 07-15 5 a10 a15 kPaò 3ñ F ² z F ²í üAh Ö Ü Ø 2015-06-20À 09-14 5 a10 a20 a30 kPaò 4ñ F ² 5 a10 kPa50 j55 d £M 5 kPa a60-65d äæÎ µj ð5 10 kPaB° eâ 20 a30 kPa z b ½ 3 6 2 2015-7-08À 09-25 5 a10 a15 kPaò 4ñ F ² z F ²í üAh 6 2 2016-04-18À 06-20 5 a10 a15 a20 kPaò 3ñ F ² z F ²í üAh ã½ 6 2 2016-06-25À 09-30 5 a10 a15 a20 kPaò 3ñ F ² 5 kPa9 20 i25 ° £MB° eâ 10 a15 a20 kPa z k Ø 2016-09-09À 11-01 4 a8 a12 kPaò 3ñ £ z £í üAh { Ø 2016-09-09À 11-01 4 a8 a12 kPaò 3ñ £ z £í üAh v i 2017-05-20À 08-05 5 kPa10ñ £ z £í üAh Kõ Ö 2017-05-20À 09-30 5 a10 a15 kPaò 5ñ £ z £í üAh rø - ] Ø 2017-08-01À 11-12 10 a15 a20 kPaò 4ñ £ z £í üAh ÿ 9à HW·¥ ɵâ9Ã¥ HWy¹1©TþîªÉ £s Ø î[1¿MlÕ ° ù b Note Irrigation duration refers to the negative pressure irrigation time, inorder to ensure the crop was surving. It begins some days later than sowing or transp lanting. [ F ²T¹ÂA¥ HLNPV ¥ P¨rT1 {µ0[ £T¹ÂA¥ HLNPV 9Q]Tþ kϵ 3Q k¥s HLNPV¥ £ 3 ÄM .ÀäæÎ Öj ð57 P Þ µâ»û ï b £M a HLNPVµâ»û ï Þ ¥ HWÐM]7 OV[C 3 Ä¥ â ï1 Ú¥ 5 kPa 10 kPa¥HLNPV b2014 M ØÉ¥Û k 5 kPa ¥HLNPV 25-30 £M a 45 j50 d äæÎ µjð5 10 kPa¥HLNPV 45 j50 d £M°k² ûεµâ eÅ ï b 2015 M ØÉ¥Ö Ü k 5 a10 kPa¥HLNPVû 50 j55 d £M 5 kPa¥HLNPV 60-65 äæÎ µj ð510 kPa ¥ HLNPV ûµâ»û ï° k² b7 2016 M 6 2É¥ ã½ k° kÉ 90P·µ 5 kPa¥ £ 7 SM7 O û»ûµâ»û ï° k² b £ Ø BÕç¥Á ÈÑ/ öÐ b 3 ÄQ¥HLNPVÏ £ 3¥ ÄMC V £Ð F ² 3 ÄQ9 V ®¿µt kÏ ÀµHLNPVÉ s{; P s ;v 7Á 3 V ëÚÑ¥] H¤ b îÁ b L ÂN[ F ²¹ÂA¥ LVPV ¯ V[ L P¨¥ V 3 îZU¥ 9 Q]Tþ k¥ a 129 ñ F ²¹ÂA¥LVPV Ϻµ 20ñ aÿ¹ 15.5¥HLNPV 3 £ ÄCKÔºµ 8 ñ aÿ¹ 6.2¥ HLNPV y¹ £ Ä7 Þ »ûµâ ï b a. zÀ k² H Àµ ÄMCÂA Àµ üAh b a kVñÏÁ 3 ÄMC ûµâ»û ï k² c a kVñÏÁ 3 ¥ ä ÄæÎþµ V Ö5¡7Áµâ»û ï Þ . a. The LNPV running very well, no oxide precipitate generated at the whole experiment duration; b. Some black oxide precipitate generated, but can continuously maintained the proper native pressure; c. Lots of black oxide precipitate generated, maybe block up the tube and lose to maintained the proper native pressure. m 2 BW k² ªA TµâD¥ Fig.2 Photographs of HLNPV when field experiments were over » 1 ù CÈÖ© µâ9ÃA TµâD 9Ð k 89 A TµâDÐ ðµâ»ûZE¥1 Ó 9¥A TµâDHLNPV 1 ¥ 9 ± Î 8Á Ö 4° Ë »¥ÓDÙ V »ûçµâ¥ÿ bâ ï ÚÕ f 9ü ø b ÂT¨ £T¹ÂA Ù ö 3 ÄCØ £µBç¥è ÂTTþ 3É ù1 É V³1 QFT¹ÂA¥ £9F ¸î byN³1³sBÕè lÐ b a £ 3Q¥ÂA b 3 “ -¥ HLNPV î ÿ “dµâ´ b HLNPV¥ eâ5 ¥ eâ´ ç¥ ÂT³1 Tþ¥] 3ɨÂ]¥µâ´üA¶÷ÐHLNPVµtZL b ÂT| eâ5 Âî ¼¥ a Ú VØA vv¹4ÚZLµ æ¿î ÿ “dµâ´ b ² Ó æ¨4NM õ¥ U j ð5 a S j ð5 a bj ð o[ ØWÉÖÌ î¥ £¹µâ9Ód 9 A TµâDHLNPV æ¨ £¥áâ ï»ûµâ æ¨ F ² £Â £A ë]¸ è b k iÏ HLNPV¥ eâÚÉ _© BW HLNPV eârTÉ 4³1s HLNPV еâ9ÓdÏCµµâ»û ¥ ·S |¤ [/² 1HLNPV µ Ú¥â ïsO qµâ»û sO q¹ 0.1 kPa 30 kPa[ ¥µâ/»ûµâ¥Mµl¿ 5 b 2vs HLNPV LBWHq/ É ùç¹ b [ £TÂA¥ 5ÕTþ ¥ 55ñ HLNPV 2 j4ñ¥ k ùW Ü b [ F ²T¹ÂA 9 ÕTþ ¥ 129 ñ LVPV 2 j3 ñ¥ k ùW µ 15.5¥ 3 £ ÄMC Ϻµ 6.2¥y¹ ä ÄæÎþ Ö5¡7Y µâ»ûÿ b 3HLNPV M¿Cµµâ»ûZE µA÷¥1 ª ] b 5.0 j20.0 kPa/ ÚºµÇ £øE aµâ,ÖÌE a £øØâE a 6 £øE¥ 9.6 j17.28 aÉ ùùl¿ £ø ØâE a 6 £ø aÈHDµâÖÌ, aÈHD * “³1È 9Ç £ø *“º HW/ b 98 HLNPV 1 ¹É HW»û“d¥µâî ÿ¹S©“dµâÚ a8l aÉ a½ Ø keL V[9}Cµ¥µâ»ûZE b Á Ë öê jЧu ¾l CÈÖ© . õB aRr £ ]·Sùî [J]. jЧ CÈÖ© . r £ ] Kõ 3É { £¥Y [J]. ÏSõ¤ SÐ 2015361 3541. Xiao Haiqiang, Liu Xueyong, Long Huaiyu, et al. The effects of soil water potential on the growth and water consumption of flue-cured tobacco[J]. Chinese Tobacco Science, 2015, 361 3541. in Chinese with English abstract [28] oZ àðöÛ© . µâ9à Kõ 3É £g æ¨ q¥Y [J]. ÏSõ¤Ð . 2016222 5260. Xiao Haiqiang, Ding Yahui, Huang Chuyu, et al. Effect of negative pressure irrigation on water fertilizer utilization and flue-cured tobacco growth[J]. Acta Tabacaria Sinica, 2016, 222 5260. in Chinese with English abstract [29] u® à C c© . µâ9Ã/]K £ Ül² 3ÉY [J]. ÏS j SÐ 2017504 689697. Zhao Xiujuan, Song Yanyan, Yue Xianlu, et al. Effect of different potassium levels on the growth of bok choy under negative pressure[J]. Scientia Agricultura Sinica, 2017, 504 689697. in Chinese with English abstract [30] Ù 3 ÜóÒ Û CÈÖ© . µâ £gB8Ä9ÃÛÁ £ a æ¨r q¥Y [J]. ±þÐg Ð 201723 2 416426. Li Shengping, Wu Xueping, Long Huaiyu, et al. Water and nitrogen use efficiencies of cucumber under negatively pressurized fertigation[J]. Journal of Plant Nutrition and Fertilizer, 2017, 23 2 416426. in Chinese with English abstract Design and experiment of heavy liquid-type negative pressure valve used for negative pressure irrigation Long Huaiyu, Zhang Huaizhi, Yue Xianlu, Zhang Renlian Institute of Agriculture Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China Abstract Negative pressure irrigation NPI is a high efficient irrigation technology which has attracted great concern from some Chinese scholars in the past decade. To produce and maintain a steady negative pressure is an essential key point for NPI, and at present there are mainly 5 s, namely hanging water column HWC, static water column SWC, climbing water column CWC, electromagnetic valve EMV and negative pressure water circulation NPWC. However, due to some inherent shortcomings, those s are not convenient to practically operate. The HWC is easily to fail due to the air embolus, the EMV and NPWC are energy-consuming, and too large heights of HWC, SWC, CWC and NPWC make them very cumbersome and not easy to install. In fact, the negative pressure results in the soil water sopping, which is always continuous, slow and unidirectional, and the function of the negative pressure maintaining device is similar to negative pressure limiting valve which does not need to act continuously or high frequently. Therefore, the heavy liquid static pressure should be theoretically used to control the negative pressure in the NPI system. It is known that 1 mmHg which can be easily determined with naked eyes can generate 0.133 kPa static pressure. Moreover, the negative pressure in actual NPI is seldom set under -30 kPa which is equivalent to 22.5 mmHg. Obviously, the negative pressure maintaining device using the static pressure of mercy whose density is the largest in the world to control the negative pressure in NPI should have high precision and small size, and be easily to operate. Accordingly, a heavy liquid-type negative pressure valve HLNPV was designed. The HLNPV consists of 3 basic interconnected parts, i.e., a U-shaped tube, an S-shaped pressure maintaining tube and a hollow ball, together with a certain amount of mercury which can be poured into them and cyclically flow in them. The negative pressure is maintained by the static pressure of the mercury in the S-shaped tube. Additionally, a device to slow down the air entering was installed between HLNPV and atmosphere, and the mercury in the hollow ball was overlapped by paraffin oil or water to prevent the evaporation of mercury. Laboratory test showed that the precision of HLNPV could reach 0.1 kPa, which is too enough for NPI, and the relative error of HLNPV with the theoretical control pressure from -5 to -30 kPa was less than 5, which is satisfactory for NPI. In the field, most paraffin oil overlapping HLNPV could steadily run for the whole experiment period of 2-3 months, while the mercury in 15.5 of the HLNPV was oxidized after running for 1-3 months, and that in 6.2 of the HLNPV was blocked up by the oxide precipitate, which caused their failure to maintain negative pressure. Water-overlapping HLNPV could steadily run for the whole experiment period of 2-4 months, while water is a theoretic volatile liquid, if the runtime is more than 4 months, the overlapping water maybe need to be complemented. In one word, the HLNPV can overcome many disadvantages of the present negative pressure maintaining s, and has the advantages of larger negative pressure, no energy consumption, small size, high accuracy, easy to install and debug, as well as more security. The mechanism, structure, application effect and suggestions for improvement of the HLNPV are described explicitly in this paper, thereby providing a reference for its further application, innovation and improvement. Keywords irrigation; design; agriculture; heavy liquidtype negative valve; negative pressure irrigation; negative pressure maintaining
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