Influence of mulch and poultry manure application on soil temperature,evapotranspiration and water use efficiency of dry season cultivated okra

Sustainable vegetable production especially during the dry season requires adequate conservation of soil water. This study was conducted to evaluate the sole and interactive effects of mulching (M) and poultry manure (PM) application on soil temperature (ST), crop evapotranspiration (ETc) and water use efficiency (WUE) of okra. The experiment was a Randomized Complete Block Design (RCBD) with three replicates. The treatments were M at 0 and 6 t ha⁻¹ and PM at 0, 10 and 20 t ha⁻¹. Soil temperature was measured using digital thermometer while ETc was determined by water depletion method using a Time Domain Reflectometer. Irrigation at field capacity was applied manually at 2-day intervals. Independent application of mulch significantly lowered ST while joint application of 20 t ha⁻¹ PM (PM20) and M significantly (p ≤ 0.05) reduced ST at 5 cm and 10 cm soil depth compared with the unmulched plots in both seasons. Application of 10 t ha⁻¹ PM (PM10) without M recorded the highest ETc (43.7 mm), while joint application of PM20 and M reduced ETc by about 93% compared with PM10 only. Okra used water most efficiently when PM20 was applied under mulched plot. There was 62.2% increase in WUE under mulched plots compared with the control while the residual effect of PM10 and M significantly increased WUE by 65.5%. It was evident that M alongside application of PM is a good strategy for regulating ST, moderating ETc and increasing okra WUE, especially during dry season farming.     

耕作和保墒措施对冬小麦生育时期光合特征及水分利用的影响

为探明不同耕作保墒措施下冬小麦生育期间光合生理特征及其增产机理,采用田间试验,以常规耕作为对照,采用深松、秸秆覆盖、免耕、施用有机肥及保水剂等措施,研究了不同耕作和保墒措施对冬小麦生育期间光合作用、产量及水分利用效率的影响。结果表明:冬小麦光合速率和叶片水分利用效率均以孕穗期最高,而灌浆期最低。蒸腾速率和气孔导度均以扬花期最高。对不同处理而言,在各生育时期均以深松处理的光合速率和叶片水分利用效率最高,其次为秸秆覆盖处理。在拔节期、孕穗期和扬花期以有机肥处理的蒸腾速率最高,而灌浆期以秸秆覆盖的蒸腾速率较高,在全生育期对照的蒸腾速率均较低。气孔导度与蒸腾速率表现规律基本一致。不同耕作、保墒措施均提高了小麦的穗数、穗粒数及千粒重,以及小麦籽粒产量和水分生产效率,降低了小麦总耗水量;各处理中以深松处理的效果最佳,其产量和水分生产效率分别较对照提高19.6%和38.3%。相关分析表明:各时期的小麦光合速率及叶片水分利用效率均与小麦产量和水分生产效率呈正相关,且随生育期的推进,其相关性增强,特别在扬花期,光合速率对于小麦产量和水分生产效率的影响更显著。     

Water transmission characteristics of a Vertisol and water use efficiency of rainfed soybean (Glycine max (L.) Merr.) under subsoiling and manuring

In Vertisols of central India erratic rainfall and prevalence of drought during crop growth, low infiltration rates and the consequent ponding of water at the surface during the critical growth stages are suggested as possible reasons responsible for poor yields (<1 t ha⁻¹) of soybean (Glycine max (L.) Merr.). Ameliorative tillage practices particularly deep tillage (subsoiling with chisel plough) can improve the water storage of soil by facilitating infiltration, which may help in minimizing water stress in this type of soil. In a 3-year field experiment (2000–2002) carried out in a Vertisol during wet seasons at Bhopal, Madhya Pradesh, India, we determined infiltration rate, root length and mass densities, water use efficiency and productivity of rainfed soybean under three tillage treatments consisting of conventional tillage (two tillage by sweep cultivator for topsoil tillage) (S₁), conventional tillage + subsoiling in alternate years using chisel plough (S₂), and conventional tillage + subsoiling in every year (S₃) as main plot. The subplot consisted of three nutrient treatments, viz., 0% NPK (N₀), 100% NPK (N₁) and 100% NPK + farmyard manure (FYM) at 4 t ha⁻¹ (N₂). S₃ registered a significantly lower soil penetration resistance by 22%, 28% and 20%, respectively, at the 17.5, 24.5 and 31.5 cm depths over S₁ and the corresponding decrease over S₂ were 17%, 19% and 13%, respectively. Bulk density after 15 days of tillage operation was significantly low in subsurface (15–30 cm depth) in S₃ (1.39 mg m⁻³) followed by S₂ (1.41 mg m⁻³) and S₁ (1.58 mg m⁻³). Root length density (RLD) and root mass density (RMD) of soybean at 0–15 cm soil depth were greater following subsoiling in every year. S₃ recorded significantly greater RLD (1.04 cm cm⁻³) over S₂ (0.92 cm cm⁻³) and S₁ (0.65 cm cm⁻³) at 15–30 cm depth under this study. The basic infiltration rate was greater after subsoiling in every year (5.65 cm h⁻¹) in relation to conventional tillage (1.84 cm h⁻¹). Similar trend was also observed in water storage characteristics (0–90 cm depth) of the soil profile. The faster infiltration rate and water storage of the profile facilitated higher grain yield and enhanced water use efficiency for soybean under subsoiling than conventional tillage. S₃ registered significantly higher water use efficiency (17 kg ha⁻¹ cm⁻¹) over S₂ (16 kg ha⁻¹ cm⁻¹) and S₁ (14 kg ha⁻¹ cm⁻¹). On an average subsoiling recorded 20% higher grain yield of soybean over conventional tillage but the yield did not vary significantly due to S₃ and S₂. Combined application of 100% NPK and 4 t farmyard manure (FYM) ha⁻¹ in N₂ resulted in a larger RLD, RMD, grain yield and water use efficiency than N₁ or the control (N₀). N₂ registered significantly higher yield of soybean (1517 kg ha⁻¹) over purely inorganic (N₁) (1392 kg ha⁻¹) and control (N₀) (898 kg ha⁻¹). The study indicated that in Vertisols, enhanced productivity of soybean can be achieved by subsoiling in alternate years and integrated with the use of 100% NPK (30 kg N, 26 kg P and 25 kg K) and 4 t FYM ha⁻¹.     

耕作方法对黄土高原旱作玉米产量和土壤水温特性的影响

全膜双垄沟播是黄土高原旱作玉米主要生产技术,但此技术的土壤耕作主要依赖传统耕作和旋耕,在形成犁底层的同时造成耕层变浅,影响玉米生长、产量形成以及土壤健康。本文以打破犁底层、改善土壤结构、提高黄土高原旱地玉米(Zea may L.)产量和有限降水资源利用效率为目标,布设大田定位试验,比较研究了深松耕、免耕、旋耕和传统耕作对旱地全膜双垄沟播玉米土壤水分、温度、土壤容重、产量以及水分利用效率的影响。结果表明:全膜双垄覆盖条件下,深松耕和免耕较旋耕和传统翻耕能有效增加0~30 cm土壤贮水量,其0~30 cm土层土壤含水量较翻耕、旋耕分别增加50.0%、43.7%和14.8%、10.3%;深松耕能有效降低5~30cm土层土壤容重,其5~10 cm和10~30 cm土层土壤容重,深松耕较传统耕作分别降低10.9%和12.9%,随着土层的加深,深松耕、免耕的土壤容重呈降低趋势,旋耕和传统翻耕呈增大趋势;深松耕在苗期、拔节—抽雄期较传统翻耕分别具有明显的增温和降温作用,有利于玉米生长和产量提高;2个平水年,深松耕处理的玉米生物产量、籽粒产量和水分利用效率分别较传统翻耕增加6.1%~5.6%、18.6%~28.8%和28.1%~32.9%,具有明显的增产和提高水分利用效率的作用。因此,在黄土高原半干旱区同等降雨条件下,深松耕能有效增加全膜双垄沟播玉米的土壤贮水量,改善土壤结构,协调水温关系,有利于增产和提高水分利用效率,是全膜双垄沟播玉米一项理想的土壤耕作方法。     

Effect of mulch and tillage system on soil porosity under wheat (Triticum aestivum)

Crop residues and reduced tillage become current tendency in modifying tillage due to better water management, organic and nutrient supply and increasing crop production. This study was carried out to quantify the effect of fodder radish mulching and different tillage systems in wheat production. In 2004–2006 the field trial was set up on Luvic Chernozems derived from loess. This experiment consisted of two factors: tillage system (conventional or reduced) and mulch (with or without). The air–water properties of soil with particular focus on macropore characteristics were investigated.The tillage system and mulch application significantly influenced physical properties of investigated soil. Reduced tillage, without mouldboard plough, increased the soil density with respect to conventional tillage. However, in the upper soil layer (0–10 cm) with mulch residues the bulk density decreased and reached the similar value as those obtained at conventional tillage (1.25 g cm⁻³). The macroporosity of soil with conventional tillage (14.79%) was significantly higher in comparison with reduced tillage (6.55%). The mulch of fodder radish added at reduced tillage increased the macroporosity in pore diameter range of 50–500 μm. These changes referred to all shape classes: regular, irregular and elongated pores. The lowest transmission pores content (0.078 cm³ cm⁻³) was noticed at the reduced tillage without mulch at the 0–10 cm layer. Due to lack of differences in storage pores the tillage and mulching had no effect on both AWC (available water content) and PWC (productive water content) values. The higher value of AWC was noticed in the upper soil layer (0.198 cm³ cm⁻³ in average), whereas in the 10–20 cm soil layer it was 0.186 cm³ cm⁻³. Similar relation was recorded in PWC values, 0.165 and 0.154 cm³ cm⁻³, respectively. The results obtained in physical properties of soil reflected in wheat yields. The yields obtained at reduced tillage system without mulch (5.54 t ha⁻¹) were significant lower with respect to treatment when mulch applied (6.79 t ha⁻¹). The mulch residues did not affect yields at conventional tillage (6.53 t ha⁻¹ without mulch and 7.00 t ha⁻¹ with mulch). The main conclusion is that the mulching can help to avoid yield reduction in wheat production when reduced tillage is used.     

耕作方式对华北冬小麦.夏玉米周年产量和水分利用的影响

在冬小麦季设置秸秆不还田翻耕(CT)、秸秆还田翻耕(CTS)、秸秆还田旋耕(RTS)和免耕秸秆覆盖(NTS)4种处理,研究耕作方式对华北小麦-玉米两熟区作物周年产量和水分利用的影响。结果表明:耕作方式对当季冬小麦产量和水分利用影响显著,对夏玉米产量和水分利用影响不大,但秸秆还田提高了夏玉米产量。RTS、CTS、CT 3个处理小麦季产量差异不显著,而NTS由于有效穗数不足,产量显著低于其他处理;与CT相比,NTS周年产量平均减产5.13%,RTS增产2.69%,CTS增产2.33%。耕作方式对当季小麦土壤水分含量影响大,而对后茬夏玉米土壤水分含量的影响较小。NTS提高了小麦季土壤水分含量,增加了土壤储水量,与CT相比,0~60 cm土壤储水量2010年和2011年分别增加39.07 mm和26.65 mm。从耗水构成来看,土壤水在冬小麦耗水中所占比例最大,其次为灌水和降水;而夏玉米耗水以降水为主,且降水中有一部分转化为土壤水储存起来。NTS提高了冬小麦季土壤储水量,降低了土壤水分的消耗,冬小麦季耗水最少。与CT相比,NTS小麦季平均节水22.40 mm,周年耗水量也以NTS最少;但NTS冬小麦产量降低导致其小麦季和周年水分利用效率均最低。从作物周年产量和水分利用的角度来看,如何提高免耕秸秆覆盖小麦季产量,进而提高周年产量,发挥其节水优势,是该耕作模式在华北地区冬小麦?夏玉米两熟区推广应用亟需解决的关键问题。     

Deep tillage and traffic effects on subsoil compaction and sunflower (Helianthus annus L.) yields

The main function of deep tillage is to alleviate subsoil compaction, but how long do the benefits of this technique remain? Traffic on loose soil causes a significant increase in soil compaction. Subsoiling and chisel plowing were carried out at 450 and 280 mm depth, respectively on a compacted soil in the west Rolling Pampas region of Argentina. The draft required, physical soil properties, root growth, sunflower (Helianthus annus L. Merr.) yield and traffic compaction over the subsequent two growing seasons were measured. Cone penetrometer resistance was reduced and sunflower yields increased following deep tillage operations. Subsoil compaction caused changes to the root system of sunflower that affected shoot growth and crop yields. Although subsoiling and chiseling had an immediate loosening effect, it was evident that after just 2 years, when traffic intensity was >95 mg km ha⁻¹, re-compaction and settling had occurred in the 300–600 mm depth range.     

不同土壤水分对赤松光合作用与水分利用效率的影响研究

在不同土壤水分条件下研究了赤松光合特征及其水分利用效率的变化。结果表明,不同土壤水分处理对赤松幼苗净光合速率、气孔导度、蒸腾速率、水分利用效率等生理指标及其日变化均产生明显影响;中度水分胁迫时赤松幼苗的光合午休比对照提前1h且午休时间长,其净光合速率和气孔导度的下降平行进行,而且,日平均水分利用效率的下降幅度比日平均净光合速率的下降幅度小。     

Effects of vetiver grass (Vetiveria nigritana) strips, vetiver grass mulch and an organomineral fertilizer on soil, water and nutrient losses and maize (Zea mays, L) yields

Soil erosion remains a serious problem on most agricultural fields especially in the humid tropics. Experiments were conducted between 2003 and 2005 to test the efficiency and efficacy of using vetiver grass strip (VGS), vetiver grass mulch (VGM) and an agronomic practice of using an organomineral fertilizer (OMF) capable of improving soil structure and a control, as treatments, on soil and water conservation and improvement of maize yields. The treatments, in three replicates, were laid out in a randomized complete block design on 7% runoff plots on an Alfisol in the sub humid region of Southern Nigeria. Soil physical conditions were significantly best under VGM plots and least under VGS plots. Nevertheless, runoff and soil loss were generally in the increasing order of VGS, VGM and OMF. Although mean runoff and soil loss on VGS plots were 36.6% and 28% of the value of the control plot in 2003, when 2 tonnes/ha of vetiver grass mulch was applied to the control plot in 2004, these values were increased to 61.5% and 48.4%, respectively indicating a significant reduction of runoff and soil loss on the mulched plots. Vetiver grass mulch (VGM) at 6 tonnes/ha was more effective than VGS plots in reducing runoff than soil loss. Whereas mean runoff for VGM, VGS and OMF plots were 28.67, 38.44 and 42.44 mm, respectively, the corresponding mean soil losses at 6 tonnes/ha were 980.5 kg/ha, 389 kg/ha and 1251 kg/ha, respectively. Mean soil losses were 629 kg/ha and 591.5 kg/ha higher on VGM than VGS plots at 4 tonnes/ha and 6 tonnes/ha, respectively. Mean No₃-N levels of runoff water on the VGS plots were 40.4% and 65.6% of the levels of the OMF and the control plots, respectively over 2003 and 2004. Nutrient loads of eroded sediments were highest for OMF plots and least for VGS plots. Carbon, Nitrogen and P contents of eroded sediments were 22–23.5%, 12–35.9%, and 20.6–37.6% lower on VGS plots than other treatments.

The significant beneficial effect of OMF in producing the highest yields was dwarfed by the potential danger of water pollution by nutrient loads in the absence of a soil erosion control measure. Although the differences were not significant, grain yields on VGM plots were 4% and 47.4% higher than on VGS plots when 4 and 6 tonnes/ha of grass mulch were applied.     

The effects of wheel-induced soil compaction on anchorage strength and resistance to root lodging of winter barley (Hordeum vulgare L.)

Lodging is the permanent displacement of cereal stems from the vertical. Cereal plants growing in the edge rows next to both wheel tracks (‘tramlines’) and the gaps between experimental plots (‘inter-plot spaces’), which are traversed by farm vehicles during planting operations and agrochemical application, are less prone to lodge than plants growing elsewhere in fields and plots. Previous research has attributed this phenomenon to an increase in the stem strength of edge row plants, and hence their resistance to stem lodging, resulting from reduced competition between edge row plants for resources. However, this explanation gives no consideration to the anchorage strength of edge row plants, and hence their resistance to root lodging. Differences in soil and plant characteristics between the edge and centre rows of plots of winter barley (Hordeum vulgare L.) were examined on sand, silt and clay dominated soil types. Edge rows next to tramlines were investigated on the silt and clay soil types, whereas edge rows next to inter-plot spaces were investigated on the sand soil type. Edge row plants next to both tramlines and inter-plot spaces had 58.8% greater anchorage strength and hence resistance to root lodging than centre row plants. This was attributed to (1) greater soil compaction in the edge rows resulting from wheel traffic in the tramlines and inter-plot spaces, which increased the strength of the soil matrix surrounding the roots, and (2) greater plant root growth in the edge rows resulting from reduced competition. Bulk density, root plate spread and structural rooting depth were 19, 22, and 12% greater, respectively, in the edge rows of all soil types. The results suggest that in order to reduce lodging risk, energies should be directed towards identifying agricultural practices that optimise soil compaction in the seedbed without causing significant limitations to root growth.     

Tillage and mulch effects on productivity and water use of pea and soil carbon stocks

Soil management can notably influence crop production under rainfed farming; however, improper soil management is one of the key factors threatening sustainability. The objective of this 3 years’ study was to evaluate the performance of two types of tillage: conventional tillage (CT) and zero tillage (ZT) systems with four mulches; paddy straw mulch (PSM), maize stubble (MS), Imperata cylendrica (thatch grass, TG) and no mulch (NM) on yield and water use of pea (Pisum sativum) and physico-chemical properties of soil. CT and PSM have registered 11.1% and 36.1% higher pod yield, 10.0% and 40% improvement of water use efficiency (WUE) and 9.7% and 49.2% better harvest monetary benefit (HMB) over ZT and NM, respectively. Soil moisture content (SMC) was higher with ZT than CT. Placement of mulch has considerably higher SMC on upper soil layer over NM, but at deeper depth, there was no such evidence. The soil organic carbon (SOC) was considerably improved by 4.1% with ZT than CT, whereas, MS improved SOC by 1.9% than NM. The findings clearly suggested that CT along with PSM registered improvement in pod yield, WUE and HMB, but ZT and MS improved SOC at different soil depths and responded to carbon stock management.     

不同覆盖材料土壤生态效应与玉米增产效应研究

田间试验研究不同覆盖材料土壤生态效应与玉米增产效应结果表明,小麦秸秆、地膜、高粱秆片和纸板覆盖均有显著保水作用及明显水分表聚现象,即0～10cm表层土壤含水量明显高于下层土壤,地膜覆盖兼有显著增温效应,而小麦秸秆、高粱秆片和纸板覆盖土壤温度却明显低于对照。除纸板外其他覆盖材料均不同程度增加0～2 0cm土层土壤细菌、真菌和放线菌数量,且以秸秆覆盖增幅最大。各覆盖处理均显著增加玉米株高、茎粗和叶面积指数,不同程度提高玉米生育前期倒1、2、3叶净光合速率。小麦秸秆、地膜、高粱秆片、纸板覆盖处理分别比对照增产19.4 %、17.2 %、16 .1%和13.3% ,其增产原因主要是由于穗长和穗粒数的增加所致     

Effects of sowing date, tillage and residue management on productivity of cotton (Gossypium hirsutum L.)–wheat (Triticum aestivum L.) system in northwest India

In southwestern region of Punjab in north India, sowing dates of cotton crop in cotton (Gossypium hirsutum L.)–wheat (Triticum aestivum L.) system are staggered from last week of April to mid of May depending upon the surface water supply from canal as ground water is not fit for irrigation. Further, farmers practice intensive cultivation for seedbed preparation and burning of wheat straw before sowing of cotton crop. With the present farmers’ practices, yields have become static and system has become non-profitable. Field experiments were conducted on Entisols for two rotations of cotton–wheat system during the years of 2004–2005 and 2005–2006 in split plot design to study the direct and interactive effects of date of sowing and tillage-plus-wheat residue management practices on growth and yield of cotton and wheat and to increase the profitability by reducing the tillage operations, which costs about 50% of the sowing cost. The pooled analysis showed that in cotton crop, there was a significant interaction between year × dates of sowing. Among different tillage-plus-wheat residue management practices yields were 23–39% higher in tillage treatments than minimum-tillage. In wheat, grain yield in tillage treatments were at par. Water productivity amongst the tillage treatments in cotton was 19–27% less in minimum tillage than others tillage treatments. Similar trend was found in wheat crop. Remunerability of the cotton–wheat system was more with a combination of reduced tillage in cotton and minimum tillage in wheat than conventional tillage.     

残茬覆盖与耕作方式对土壤性状及夏玉米水分利用效率的影响

采用田间和小面积模拟降水试验的方法,对小麦机械收获后残茬覆盖与不覆盖两种条件下免耕、翻耕和间隔深松3种土壤耕作方式夏玉米田的土壤物理性状和水分利用效率进行了研究。结果表明,残茬覆盖与深松相结合,可平衡和改善耕层土壤温度状况,在土壤温度较低时具有保温作用,在土壤温度较高时具有降温作用;可以增加土壤的蓄水和保水能力,模拟降水后24 h测定1 m土层含水量比免耕不盖多26.1 mm,全生育期平均耕层土壤含水量比免耕不覆盖高9.37%;土壤通透性也得到改善;最终水分利用效率比免耕不盖提高25.26%。     

耕作与施肥对旱地玉米田土壤耗水量和水分利用效率的影响

为探究保护性耕作与施肥对渭北旱地春玉米田土壤耗水量和水分利用效率的影响,达到高效生产的目的。于2013—2015年在渭北旱塬实施了春玉米耕作与施肥田间试验,共设置6种耕作与施肥处理:翻耕+低肥(A1)、免耕+高肥(A2)、深松+平衡施肥(A3)、翻耕+无肥(B1)、免耕+无肥(B2)和深松+无肥(B3),测定了春玉米休闲期与生育时期0~200 cm土层土壤蓄水量和收获时籽粒产量。结果表明:1)保护性耕作能显著提高旱地玉米田土壤蓄水保墒能力。与传统翻耕处理B1相比,休闲期,B2和B3播前土壤蓄水量分别提高23.39 mm和27.73 mm(P0.05);耕作处理区,B2和B3全生育期土壤蓄水量平均提高13.41 mm和15.70 mm;耕作施肥处理区,A2、A3土壤蓄水量较A1分别提高13.15 mm、19.54 mm。2)平衡施肥能有效提高玉米全生育期平均土壤蓄水量,与不施肥处理相比,全生育期土壤蓄水量平均提高6.79 mm(P0.05)。3)保护性耕作与施肥能提高玉米籽粒产量与水分利用效率。耕作无肥处理区,与B1比较,B3处理产量提高212~576 kg×hm~(-2),水分利用效率提高0.83~2.21 kg×hm~(-2)×mm~(-1);耕作施肥处理区,A3产量与水分利用效率提高最为显著,产量较A1提高659~1 495 kg×hm~(-2),水分利用效率提高0.65~3.82 kg×hm~(-2)×mm~(-1)(P0.05)。3种施肥方式下以氮、磷、钾平衡施肥产量与水分利用效率提高幅度最大。4)对耗水量与产量进行相关性分析发现,抽雄—灌浆生育阶段土壤耗水量与产量呈显著正相关,保护性耕作提高玉米生长初期土壤蓄水保墒能力,提高春玉米抽雄—灌浆期土壤水分,增加作物生长关键时期对水分的利用效率,利于玉米籽粒产量的提高。因此在渭北旱地春玉米田,深松与平衡施肥组合能提高春玉米产量与水分利用效率,是该地区玉米高效生产较为适宜的种植模式。     

Mulch effects on rainfall interception, soil physical characteristics and temperature under Zea mays L.

Application of organic amendment to the soil surface is widely used in order to ameliorate topsoil physical conditions, especially with respect to temperature, evaporation and water content. Water intercepted by mulch and crop canopy involves loss through evaporation that never replenishes the soil water. In this study, hydrological and temperature conditions beneath mulches of manufactured materials, organic waste, wheat straw (Tritium aestivum L.) and soybean straw (Glycine max L. Merrill) applied at different thickness were investigated in glasshouse and field conditions in southern England. Interception loss by a maize (Zea mays L.) canopy and mulch modified the soil water balance by adversely affecting soil water content beneath thicker application. Mulching had a beneficial effect on soil water and temperature regimes. These findings are important for identifying mulching practices for dryland agriculture and under scenarios of climatic change that predict lower rainfall and higher temperatures in summer.     

不同深度土壤控水对稻田土壤微生物区系及细菌群落多样性的影响

为研究不同深度土壤控水对壤土稻田土壤水势、微生物区系和细菌群落多样性的影响,通过土培池栽试验,在水稻生育后期设置土壤深度0~5 cm（S05）、0~10 cm（S10）和0~15 cm（S15）控水处理,以保持水层为对照,分析了不同深度控水处理下5 cm、10 cm、15 cm深土壤水势与土壤微生物区系、细菌群落多样性的变化。结果表明：土壤5 cm、10 cm、15 cm深度的水势随着控水深度增加而降低,S05控水处理主要影响上层（5 cm）土壤水势,S10控水处理影响上、中层（10 cm）土壤水势,S15控水处理土壤水势随土层深度的增加而升高。花后8 d和32 d,S05控水处理上层土壤细菌数量显著高于S10、S15控水处理;花后16~24 d,S05控水处理中层、下层（15 cm）土壤细菌数量均显著高于S15控水处理;土壤水势与水稻生育后期中、下层土壤细菌数量呈极显著正相关关系。S05控水处理10 cm、15 cm土层的细菌丰富度Chao指数均显著高于S15控水处理及CK。3个控水处理中,5 cm土层细菌的多样性Shannon指数以S05控水处理最低。优势细菌菌群分析发现,优势群落主要为变形菌门、绿弯菌门、酸杆菌门、拟杆菌门,四者总相对丰度在80%以上;S15控水处理中层土壤变形菌门相对丰度低于S05和S10控水处理。3个控水处理土壤样品中优势纲（相对丰度大于2%）达15个,主要包括α-变形菌纲、β-变形菌纲、δ-变形菌纲、厌氧绳菌纲等,这4个纲的总相对丰度在47%以上,其中厌氧绳菌纲相对丰度最高;上层土壤中S05控水处理的β-变形菌纲相对丰度显著低于S10和S15控水处理。因此,不同深度土壤控水对壤土土壤水势、细菌数量存在影响,改变了细菌的多样性及丰富度,对土壤细菌优势菌种类无显著影响。     

Modifying profile water storage through tillage,herbicide, chemical evaporation retardent and straw mulch and its effect on rainfed chickpea (Cicer arientinum L.)

The influence of tillage, herbicide (paraquat), evaporation retardents (white opaque polythene and hexadecanol) and straw mulch, applied in the post-monsoon pre-seeding period, on soil moisture conservation and yield of chickpea (Cicer arietinum L.) was studied in a 2-year field experiment. These practices all proved to be useful in conserving more soil moisture in the 180 cm deep soil profile. Opaque polythene conserved most moisture, followed by straw mulch with an average increase of 47 mm (24%) and 32 mm (16%) over the control. Polythene and straw mulch greatly improved moisture in the seeding zone; tillage, hexadecanol and paraquat were also useful. Soil moisture conservation treatments improved plant stand, profile water use, yield and yield components. The effect of treatments varied with crop season rainfall. In the first year, with low rainfall (51 mm), polythene and straw mulch significantly increased the grain yield over other treatments. Hexadecanol, tillage and herbicide also tended to increase yields. In the second, wetter crop season (rainfall 139 mm), the differences in yield between treatments were not significant though the trend was similar to the dry year. Polythene and straw mulch increased yields over the control by 690 and 536 kg/ha in the first year and 399 and 281 kg/ha in the second year. Polythene and hexadecanol being costly, straw mulch, tillage and herbicide offer scope for adoption at field scale.     

Effect of tillage and mode of straw mulch application on soil erosion in the submontaneous tract of Punjab, India

The submontaneous tract of Punjab comprising 10% of the state, is prone to soil erosion by water. Soils of the area are coarse in texture, low in organic matter and poor in fertility. High intensity rains during the monsoon season result in fertile topsoil removal. There is an urgent need to control soil erosion in this region so as to improve soil productivity. A field study was conducted to estimate the effect of tillage and different modes of mulch application on soil erosion losses. Treatments comprised two levels of tillage, viz. minimum (T_m) and conventional (T_c) in the main plots and five modes of straw mulch application, viz. mulch spread over whole plot (M_w), mulch spread on lower one-third of plot (M_1/3), mulch applied in strips (M_s), vertical mulching (M_v) and unmulched control (M_o), in subplots in a replicated split plot design. Rate of mulch application was 6 t ha⁻¹ in all modes. Compared with M_o, M_w reduced runoff by 33%. Runoff and soil loss were 5 and 40% higher under T_c than under T_m. Though other modes of straw mulch application (M_1/3, M_s and M_v) controlled soil loss better than M_o, their effectiveness was less than M_w. T_m was more effective in conserving soil moisture than T_c. Compared with M_o, M_w had 3–7% higher soil moisture content in the 0–30 cm soil depth under T_m. Minimum soil temperature of the surface layer was 1.4–2.4 °C lower under M_w than under M_o. Straw mulching reduced maximum soil temperature and helped in conserving soil moisture. Minimum tillage coupled with M_w was highly effective in reducing soil erosion losses, decreasing soil temperature and increasing moisture content by providing maximum surface cover.     

Effect of puddling intensity on temporal variation in soil physical conditions and yield of rice (Oryza sativa L.) in a Vertisol of central India

Puddling as well as no-puddling for growing transplanted and direct seeded rice, respectively, have their disadvantages as well as advantages on the physical condition of the soil and yield of rice. The soil that is more susceptible to changes in structure is easy to puddle. However, what should be the extent of puddling is not well established. Generally, farmers have a tendency to create a very fine puddle that actually may not be required. Keeping in view the current global emphasis on conservation of resources as well as reduction of the production cost to improve the economic gain of farmers, this study attempted to find out the influence of varying intensities of puddling on the soil physical condition and rice yield (cv. IR 36) in a Vertisol of central India. The study was conducted over two cropping seasons during year 2000 and 2001. Three puddling intensities i.e. no-puddling (P₀), and puddling by four (P₁) and eight (P₂) passes of a 5 hp power tiller were evaluated.

The aggregate mean weight diameter (AMWD) of soil (0–15 cm depth) for P₀ remained almost unchanged till harvest. At 15 days after puddling, AMWD in P₁ and P₂ compared to P₀ was less by 45 and 59% in the first year and by 60 and 69% in the second year, respectively. These values at harvest changed to 22 and 46% in the year 2000 and 28 and 43% in the year 2001, respectively. Soil bulk density (BD) and penetration resistance (PR) increased significantly from transplanting to harvest in puddled soil, but in unpuddled soil significant increase in PR only at the surface 0–7 cm layer was observed. Higher intensity of puddling favoured more soil wetness at harvest, as the puddled soil maintained 25% more water than P₀. Compared to P₁, P₂ showed an increase of 4.3, 10.3 and 7.7% in length, width and depth of cracks, respectively, while the increase in P₁ over P₀ in the same order was 35, 23.5 and 13.3%, respectively. Thus, crack dimensions (length, width and depth) were larger under high intensity of puddling. Water loss through seepage plus percolation was significantly higher in P₀ as compared to P₁ and P₂ and the higher intensity of puddling reduced the losses more. The grain yield of P₂ was slightly higher than P₁ but both were significantly above P₀. Higher grain yield resulted in 46 and 49% more water use efficiency under P₁ and P₂ than P₀, respectively. This 2-year study has shown that puddling beyond P₁ i.e., four passes of a 5 hp power tiller may not be required to obtain higher yield or other benefits in Vertisols having similar hydrology to that reported here. Puddling only to the required level will also deteriorate less the soil physical condition as compared to more intense puddling. The unpuddled direct seeded rice maintained the soil in a better physical condition but the yield was significantly lower in relation to the puddled ones.