王秋菊,刘 峰,高中超,贾会彬,张劲松,张春峰,常本超,姜 辉
黑土立体休闲技术改土增产效果
王秋菊1,刘 峰2,高中超1※,贾会彬3,张劲松1,张春峰3,常本超1,姜 辉2
(1. 黑龙江省农业科学院土壤肥料与环境资源研究所,哈尔滨150086; 2. 黑龙江省农业科学院科研处,哈尔滨150086;3. 黑龙江省农业科学院佳木斯分院,佳木斯154007)
为了打破犁底层障碍,消减连作障碍,分别在轮作和连作的黑土上采用分层深耕犁将0~20 cm耕层土与>20~40 cm下层土进行转换,以达到休闲表层土壤的目的。采用大区对比法连续2年调查改土后效果。结果表明:第1年、第2年立体休闲处理较对照组未改土,0~40 cm土层土壤平均容重分别降低0.05、0.11 g/cm3;通气系数分别提高14.97×10-2、16.69×10-2cm/s;而饱和导水率较对照组第1年降低了3.14×10-3cm/s,第2年提高了10.95×10-3cm/s;抗剪强度较对照组第1年降低了0.72 kPa,第2年提高了0.82 kPa;土壤平均含水率提高分别提高4.07%、4.95%;温度分别提高0.78、0.13 ℃。立体休闲后表层土壤有机质、碱解氮、速效磷和速效钾降低、下层土土壤肥力增加。在轮作条件下,立体休闲后第1年马铃薯和甜菜分别减产5.63%和3.06%;第2年玉米和马铃薯分别增产5.20%和27.00%。在大豆连作条件下,立体休闲区植株干质量平均比对照提高7.63~7.82%;根干质量提高7.61%~13.41%;根长增加4.42%~6.26%;单株荚数增加18.83%~20.71%;株粒数增加幅度为32.43%~37.21%;根瘤数每株增加1.46~5.15个;产量比对照增加3.09%~22.38%。
土壤;作物;物理性质;产量;黑土;立体休闲;连作障碍
黑土是中国东北地区最重要的耕地土壤资源之一,以腐殖质深厚、土壤肥力高著称。据调查,黑土的腐殖质层厚度一般为30~70 cm以上,土质肥沃,疏松绵软,土壤产能高[1-2]。但由于黑土主要分布在丘陵曼冈地带,地势高,开垦早,由于长期忽视地力培肥,水土流失严重,黑土层变薄,土壤肥力不断下降[3]。特别是近10 a来,随着农村老龄化,农作业向轻简化方向发展。农田基本整地由原来的以翻耕为主变为以旋耕灭茬为主,耕层变浅,犁底层位置由原来的地表下18~22 cm上移到12~15 cm,有效土层变浅,土壤生产潜力受到制约;粮食增产由原来的依靠地力转向依靠化肥[4-6],而大量施用化肥又增加土壤负荷,污染环境。因此农业部提出减化肥、减农药计划,倡导增施有机肥提升地力,改善耕地质量[7-9]。另一方面,随着一些效益高的作物种植面积不断扩大,种植业结构趋于单一,连作面积逐年加大,连作障碍频频发生,导致农产品产量下降、品质降低[10-13]。
大量研究证明,黑土增施有机肥、秸秆深埋还田,对于增加耕层厚度,改善地力和提高作物产量有重要作用[14-18];而轮作、土壤消毒、改善施肥等技术对于消减作物连作障碍效果十分明显[19-22],但上述技术在实际应用中受到各方面条件限制。本文提出的“立体休闲改良土壤的技术”,就是根据土地休闲休耕原理,针对土壤存在的连作障碍,充分利用黑土腐殖质层深厚的特点,将多年连作的耕层土壤定期翻到下层进行休闲,实现上下层土壤轮换使用,达到休闲耕层土壤、实现农业可持续发展目的[23-24]。本文是在多年连作和正常轮作换茬的黑土上开展的多点试验研究,试图通过比较研究明确“立体休闲技术”的改土增产效果,为该技术的推广提供技术支持。
1.1 试验地点和供试土壤
试验分别在黑龙江省依安县长山村、依安县农技推广中心试验地,嫩江县农业技术推广中心示范园区试验地、宝清县农业推广中心示范园区试验地。供试土壤为黑土,土壤农化性质和耕种情况如表1所示。
表1 供试地点土地基本情况
1.2 试验设计
采用大田对比试验,设置如下2个处理:
1)对照区(CK):采用浅翻深松犁作业(上翻12 cm,下松10 cm),总作业深度22 cm。
2)立体休闲区(SL):采用自主研发的分层深耕犁,作业幅宽为100 cm,总作业深40 cm。该机械为4铧分层耕作犁(图1a),其中第1、第3犁为超大犁壁铧式犁,耕翻下层土,第2、第4犁为短犁壁铧式犁,耕作表层土。作业原理如图1b所示,作业前地表处于平整状态(图1b-1),作业时,首先开出1条深20 cm,宽50 cm的浅堑沟(图1b-2),为耕翻处理做好准备;然后位于前面的第1犁在所述的浅堑沟内作业,将>20~40 cm下层土耕起翻扣在已翻过来的表层土上,其后形成一条深40 cm的深堑沟(图1b-3);位于其后第2犁将邻近的0~20 cm表层土翻扣在所述的深堑沟中,并形成新的浅堑沟(图1b-4);后面的第3犁在浅堑沟中作业,将>20~40 cm的下层土耕起翻扣到所述的深堑沟中的表层土之上(图1b-5),第4犁随后将邻近表土反扣在深堑沟中(图1b-6),从而完成一次立体休闲作业。在下一次耕作时重复上一次作业模式。试验处理面积0.1~1.2 hm2,无重复。
施肥均按照当地常规施肥方法及用量进行施肥,于春季播种时直接起垄施肥。不同处理间施肥量及施肥方法一致。耕种情况及施肥量如表2。
表2 供试土壤生产管理状况
1.3 调查项目与方法
1)采样及测定方法
试验区处理后第2年秋季取样,在每个处理区的中心部位挖一个60×60×60 cm3土壤剖面,按照0~10、>10~20、>20~30、>30~40 cm分层,采用100 mL的环刀取原状土,3次重复。用胶带密封;同时采取非原装土样500 g,其中0~20 cm表层土壤按S型取样,5点混合后带回实验室备用。
土壤容重采用环刀法测定、土壤含水量采用烘干法测定;土壤抗剪强度采用荷兰EIJKELKAMP公司(型号:GEONOR72572)土壤剪切仪测定;土壤通气系数采用日本Daiki公司(型号:DIK-5001)土壤透气性测定仪测定;土壤透水系数采用日本Daiki公司(型号:DIK-4012)土壤透水性测定仪测定[25]。
土壤有机质采用重铬酸钾外加热法测定,碱解氮采用扩散吸收法测定,有效磷含量测定采用碳酸氢钠提取法测定,速效钾含量测定采用盐酸浸提-AAS法测定[26-27]。
2)作物生育性状调查
大豆始花期选取有代表性植株连续10株,调查根长、根瘤个数,地上、地下部干质量。
3)作物产量调查:作物成熟期每区选3点,每点取连续10株进行考种,马铃薯、甜菜采用马铃薯专用收获机和甜菜专用收获机进行全区收获,玉米、大豆采用约翰迪尔联合收割机全区收获,收获后测定每区产量。
2.1 立体休闲对土壤物理性质的影响
表3是依安农技中心试验区土壤物理性质的调查结果。从表3看出,立体休闲在降低土壤容重、提高土壤通气性和土壤含水量等方面效果显著,2年结果相对趋势一致。第1年、第2年立体休闲处理较对照组,0~40 cm土壤平均容重分别降低0.05、0.11 g/cm3;通气系数分别提高14.97×10-2、16.69×10-2cm/s;而饱和导水率较对照组第1年降低了3.14×10-3,第2年提高了10.95×10-3cm/s;抗剪强度较对照组第一年降低了0.72 kPa,第2年提高了0.82 kPa;土壤平均含水率提高分别提高4.07%、4.95%;温度分别提高0.78、0.13 ℃;从表3还可看出,立体休闲改善下层土物理性质的效果更为明显。
表3 不同处理土壤物理性质(依安农技中心)
2.2 立体休闲对土壤养分影响
图2是长山试验点处理后第2年土壤养分测量结果。立体休闲将下层土翻到表层后土壤化学养分分布与对照相比呈相反的趋势,表层土壤有机质、碱解氮、速效磷和速效钾均有降低趋势;而下层土高于对照。总体看,表层土壤整体肥力下降可能会影响作物初期生育,但下层土肥力高则利于作物根系向下伸展,利于作物后期生长。
2.3 对连作大豆生育影响
表4是嫩江农技中心试验点在大豆花期的生育调查以及成熟期的产量性状调查结果。从表4看出,立体休闲区大豆植株干质量平均比对照提高7.63%~7.82%;根干质量提高7.61%~13.41%;根长增加4.42%~6.26%;根瘤数增加1.46~5.15个/株。成熟期调查大豆单株荚数和株粒数,休闲后单株荚数增加18.83%~20.71%;株粒数增加32.43%~37.21%。
图3、4分别是嫩江试验点大豆生育中期和成熟期植株图片。从图3、图4看出,立体休闲区大豆根系量多、粗壮,根瘤多;成熟期植株高比对照明显高,植株结荚数差异也十分明显。
2.4 对作物产量影响
依安长山试验点在南瓜茬上进行的立体休闲改土作业,改土后分别种植马铃薯和甜菜,轮作顺序分别为马铃薯—玉米、甜菜—马铃薯。产量调查结果如表5所示,立体休闲后第1年马铃薯和甜菜分别减产5.63%和3.06%,但减产幅度不大。这与立体休闲后深层土壤翻到耕层,耕层土壤养分下降有关。经过1年土壤熟化后,第2年玉米和马铃薯分别增产5.20%和27.00%。在正常轮作条件下,立体休闲后第1年会导致作物减产,但第2年则表现增产,其中马铃薯增产效果好于玉米。
表6是大豆连作土壤上立体休闲后大豆产量。依安、嫩江和宝清3个试验点连续2 a大豆产量调查结果表明,立体休闲可以比对照增产3.09%~22.38%,但各地区增产幅度不完全一致,可能与各点连作障碍的轻重有关。
表4 不同处理大豆生育性状(嫩江)
表5 立体休闲的增产效果(依安县长山村)
表6 立体休闲消除大豆连作障碍的效果
立体休闲虽然是一种新的改土理念,但属于深耕技术的范畴。不同的是,传统的深耕是采用传统的铧式犁将表层土和下层土同时翻转90°~120°,由于在耕翻时土壤在犁壁作用下崩解破碎产生上下土层混合现象,有相当一部分上层土壤仍滞留在表层内,达不到休闲目标;而立体休闲耕作是使用特殊的分层深耕犁,将表层土深埋到下层,实现上下土层位置轮换,无土层之间的混层现象。
在广大的黑土区域,由于长期以来种植结构单一,残留农药污染严重,限制轮作倒茬;加之浅耕导致犁底层上移,限制作物根系下扎。高中超等[24]采用土层置换技术修复除草剂污染土壤,取得明显效果,本研究是通过立体休闲减缓作物连作障碍。应用立体休闲技术同时存在正负双方面的效应,一是改良土壤物理性质的正效应,二是由于上下土层翻转导致表层肥力降低带来的负效应。由于正负效应相互抵消作用,在改土后第1年种植玉米和马铃薯均表现略减产;第2年增产,说明翻转到表层的下层土壤在经过1年的熟化后,土壤化学肥力得到恢复;试验表明,立体休闲后连续种植大豆表现持续增产,意味着连作障碍是导致大豆产量降低的主导因素,一方面说明立体休闲消减连作障碍的作用大于表层肥力降低带来的负效应,另一方面也可能与大豆本身有固氮能力有关。因此,在技术应用初期阶段,应适当配合增施肥料以减轻负效应,提高增产效果。立体休闲或深翻由于会使深层生土翻到表层,使表层土壤养分下降,因此在实际操作中要选择黑土层深厚的地块,以达到原位立体休闲的目的。实施以消减连作障碍为目的的立体休闲改土,建议3~5 a进行一次。今后应深入开展对土壤微生物区系影响方面研究,探讨机理。
本研究采用大型机械进行田间改土作业,作业精度存在一定误差,所取得的产量等数据皆为大田实测值,可能对试验数据精度有一定影响,但从多点调查结果看,结论是一致的,由此可见研究得出的数据是可信的。
通过在轮作和连作的黑土上开展立体休闲技术改土效果研究,得到如下结论:
1)第1年、第2年立体休闲处理较对照组未改土,0~40 cm土层土壤平均容重分别降低0.05、0.11 g/cm3;通气系数分别提高14.97×10-2、16.69×10-2cm/s;而饱和导水率较对照组第1年降低了3.14×10-3cm/s,第2年提高了10.95×10-3cm/s;抗剪强度较对照组第1年降低了0.72 kPa,第2年提高了0.82 kPa;土壤平均含水率提高分别提高4.07%、4.95%;温度分别提高0.78、0.13 ℃。
2)立体休闲后表层土壤有机质、碱解氮、速效磷和速效钾降低、下层土土壤肥力增加。
3)在轮作条件下,立体休闲后第1年马铃薯和甜菜分别减产5.63%和3.06%;第2年玉米和马铃薯分别增产5.20%和27.00%。在大豆连作条件下,立体休闲后没有减产现象,大豆连年增产,产量比对照增加3.09%~22.38%。
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Effect of improving black soil and crop yield by using soil layer up-down fallow technology
Wang Qiuju1, Liu Feng2, Gao Zhongchao1※, Jia Huibin3, Zhang Jinsong1, Zhang Chunfeng3, Chang Benchao1, Jiang Hui2
(1.,,150086,; 2.,,150086,; 3.,154007,)
Black soil is one of the most important cultivated land resources in Northeast China. Black soil has high soil fertility, and brings about high and stable yield. According to the survey, the humus layer of black soil is generally 30-70 cm. But black soil is on high terrain and the cultivation time is long, coupled with the neglect of enhancing soil fertility management, which lead to serious soil erosion, soil layer thinning, and soil fertility decline. Especially in the past 10 years, in order to save costs, farmers have widely used simplified technology, and the basic soil tillage method has changed from plowing to rotary tillage and stubble cleaning, which has resulted in shallow tillage layer and increased the bottom thickness. The depth of the plough bottom moves from 18-22 to 12-15 cm, and the potential productivity of black soil is restricted. People try to stop the decline of soil fertility and soil thinning by improving the application of organic fertilizer, straw returning and subsoiling technology. Our research group found that the straw deep buried and organic fertilizer application have effectively improved soil fertility. In view of removing the obstacle of continuous cropping, the existing technologies including the nutritional therapy, soil disinfection, and crop rotation technology had the problem of high cost and were difficult in the rotation of crops. Therefore, these techniques were limited to solve the problem of soil continuous cropping obstacles. According to the principle of land fallow for leisure, the technology of improving soil by stereo leisure was presented in this paper, which was aimed at continuous cropping obstacles in soils. Through making full use of the characteristics of black soil with deep humus layer, continuous cropping soil was regularly turned to lower leisure. By alternate use of upper and lower soil, the objectives of soil leisure and agricultural sustainable development would be achieved. In this paper, a machine developed to turn the top soil to the lower layer was operated in the black soil field for breaking its hard plough pan. As the depth of top black soil is more than 40 cm, it has good homogeneity from up part to low part, which can provide a choice for developing soil layer up-down fallow technology. Two test fields were selected. One was operated by above mentioned machine, and the other was operated by conventional machine. The results showed that in the up-down fallow field the soil bulk density was decreased by 0.05, 0.11 g/cm3respectively compared with that in the conventional field. The soil aeration coefficient was increased by 14.97×10-2, 16.69×10-2cm/s respectively in the first year and second year. The soil saturated hydraulic conductivity was reduced by 3.14×10-3in the first year, increased by 10.95×10-3cm/s in the second year. The soil shearing strength was reduced by 0.72 in the first year, increased by 0.82 kPa in the second year, and the soil moisture content was increased by 4.07%, 4.95% respectively in the first year and second year. It was also found that in the up-down fallow field, soil chemical index including soil organic matter, alkali-hydrolysable nitrogen, available phosphorus and available potassium tended to be lower in the upper layer but higher in the down layer. Under the rotation conditions, the yield of potato and beet in the up-down fallow field was decreased by 5.63% and 3.06% respectively in the first year, but the yield of corn and potato increased by 5.20% and 27.00% respectively in the second year. Under the soybean continuous cropping conditions, soybean grew well in the up-down fallow field, dry weight and root dry weight of soybean were increased by 7.63%-7.82% and 7.61%-13.41% respectively, root length was increased by 4.42%-6.26%, pod number and grain number per plant were increased by 18.83%-20.71% and 32.43%-37.21% respectively, and nodule number was increased by 1.46-5.15. During the 2 tested years, soybean yield in the up-down fallow field was 3.09%-22.38% higher than that in the conventional field.
soils; crops; physical properties; yield; black soil; soil layer up-down fallow; continuous cropping obstacle
10.11975/j.issn.1002-6819.2017.06.013
S281
A
1002-6819(2017)-06-0100-07
2016-09-21
2017-03-07
公益性行业(农业)科研专项(201303126-7);省招标项目(GA14B101-A04);国家科技支撑计划(2014BAD11B01-A027)
王秋菊,女,黑龙江省依兰人,博士,副研究员,从事土壤改良研究。哈尔滨 黑龙江省农业科学院土壤肥料与环境资源研究所,150086。Email:bqjwang@126.com.
高中超,男,黑龙江绥棱人,副研究员,研究方向为土壤改良。哈尔滨 黑龙江省农业科学院土壤肥料与环境资源研究所,150086。Email:gaozhongchao0713@163.com