The role of tillage and crops on a soil loss of an arable Stagnic Luvisol

The poor physical, chemical and biological properties make Stagnic Luvisol highly susceptible to water erosion on sloping terrains. The objective of this paper is to estimate the effect of different tillage treatments and crops (maize, soybean, winter wheat, spring barley, oilseed rape) on water erosion. The highest erosion in investigation period (1995–2014) was recorded in the control treatment with fallow, followed by the treatment that involved ploughing and sowing up and down the slope. Significantly, lower soil losses were recorded in no-tillage and treatments with ploughing and sowing across the slope. Regarding the crops significantly higher soil losses were recorded in spring row crops (maize and soybean) compared to high-density winter crops (wheat and oilseed rape) and double crop (spring barley with soybean). In the studied period, an average loss of 46 mm of the plough layer was recorded in the control treatment, while in treatment with ploughing and sowing up and down the slope average annual soil loss was 10 mm. According to the results of this study no-tillage and tillage across the slope are recommended as tillage which preserves soil for the next generations in agro-ecological conditions of continental Croatia.     

Effects of reduced tillage and liming on microbial activity and soil properties in a weakly-structured soil

The effects of reduced tillage and lime on crop yield and soil physical and microbial properties were studied in a weakly-structured silty clay loam soil. Two autumn primary tillage practices were compared, mouldboard ploughing to 20–25 cm and cultivation to 12 cm. Seedbed preparation was carried out by several harrowing operations in the mouldboard ploughed treatment, and with a PTO-driven harrow in the same operation as sowing in the shallow cultivation treatment. The tillage treatments were applied alone or were combined with liming aimed at soil structural improvement. Lime was added as 6.5 Mg CaO ha⁻¹ before the start of the experiment and mixed into the top 12 cm of soil with a disc cultivator. A 4-year crop rotation was used: spring barley, spring oilseed rape, spring/winter wheat and oats, and all crops were compared each year. Crop residues were retained in the experiment and incorporated at cultivation. Aggregate stability was improved by the shallower tillage depth, probably as an effect of an increase in soil organic matter and a more active microbial biomass. Liming had little effect on soil structure variables but increased microbial activity to some extent. This was reflected in higher crop yields, especially when the shallow tillage depth was combined with liming. Penetration resistance in the seedbed subsoil was highest when mouldboard ploughing was carried out in plots without liming. Data were examined with principal component analyses, and the structures in the data were presented as scores and loading plots, which revealed groupings between samples and relationships between variables, respectively.     

胡麻田施用噻吩磺隆对后茬作物的安全性研究

为了探明胡麻田施用除草剂噻吩磺隆对后茬作物的安全性,以期为施用噻吩磺隆胡麻田后茬作物的合理布局提供依据。采用大区对比试验设计,设15%噻吩磺隆低剂量和高剂量两个施药处理和清水对照,研究对后茬作物玉米、春油菜、荞麦、大豆、向日葵、马铃薯出苗生长和产量的影响,结果表明,胡麻田喷施15%噻吩磺隆345 g/hm2(低剂量),对玉米、大豆、向日葵、荞麦和马铃薯等5种后茬作物的出苗、株高、产量均无明显影响,相对出苗率均超过98.4%,株高抑制率为0.14%~1.41%,减产幅度在1.00%左右。喷施15%噻吩磺隆525 g/hm2(高剂量),对上述5种后茬作物株高和产量的负面影响均有所增强,对玉米、大豆、向日葵和马铃薯出苗率无明显影响,相对出苗率均达96.6%以上;对荞麦出苗影响显著,相对出苗率为95.93%,株高抑制率为0.42%~6.74%。胡麻田喷施低剂量、高剂量噻吩磺隆对后茬玉米、大豆、向日葵、荞麦和马铃薯均安全,对春油菜具药害。结合作物的抗药性及对环境的适应性综合评判,在甘肃省陇东地区,施用噻吩磺隆的胡麻田后茬可安排种植玉米、大豆、向日葵和马铃薯,不宜种植荞麦和春油菜。     

Enhancing Environmental Performance with Winter Cover Cropping after Potato Harvest in Eastern Canada

ABSTRACT

In humid climates, the risk of nitrate leaching and topsoil loss due to erosion is high on bare soil in the fall after potato (Solanum tuberosum L.) harvest and in the spring with snowmelt. This 2-year study (2016–2017) compared three winter cover crops. Two of these are used as cash crops (winter rye [Secale cereale L.], winter wheat [Triticum aestivum L.]), and one is a winter-killed cover crop (spring barley, Hordeum vulgare L.). They were all seeded on two dates after potato harvest (end of September or first week of October) in Prince Edward Island, Canada. The measured parameters included soil nitrate measured at different times in fall and in the following spring and summer, splash detachment, C and N contents in splashed sediments, cereal straw dry matter yield, and cereal grain yield. In both years, all winter cover crops decreased splash detachment compared with the no winter cover control, with winter rye having the greatest reduction. A similar trend was observed for C and N contents in splashed sediments. There was a trend toward lower soil nitrate following winter cover crops in comparison with bare soil, but the trend was not consistent across trials and sampling dates. Winter wheat grain yield ranged from 4.5 to 7.6 Mg ha^?1, while that associated with winter rye ranged from 3.2 to 5.1 Mg ha^?1. Therefore, winter cereal seeded after potato harvest can constitute a good source of revenue while mitigating the risk of soil erosion and reducing nitrate leaching in some cases.     

Plant elemental composition and element ratio in some crops at the flowering stage

Abstract

The elemental composition of winter wheat, spring barley, oat, rye, buckwheat and potato at flowering stage as well as the molar ratio of elements to each other in these crops were determined. Presented is a new theoretical approach to fertilization based on the view that knowing the ratio of elements in crops at the flowering stage can be useful in determining the appropriate ratios of fertilizer components in plant nutrition and fertilization.     

Long-term energy use and economic evaluation of three tillage systems for cereal and legume production in central Spain

Three different experiments have been carried out in the area to the northeast of Madrid (central Spain) over 10 years with winter wheat (Triticum aestivum L.), winter barley (Hordeum vulgare L.), spring barley and vetch (Vicia sativa L.) grown for hay. In these experiments, three tillage systems were compared: conventional tillage (primary tillage was mouldboard ploughing to 300 mm depth), minimum tillage (primary tillage was spring tine cultivation either with a chisel or a cultivator to 150 mm depth) and zero tillage (direct drilling), in relation to energy consumption, production costs, energy efficiency and productivity, and economic returns. The experiments were performed on a Vertic Haploxeralf of a clay loam texture.The aforementioned variables were calculated considering every input (i.e. fertilisers, seeds, herbicides, machinery and fuel) including all the labour practices performed to harvesting. Post-harvesting activities were not included.The results showed that important energy and production cost savings may be achieved through minimum tillage and zero tillage, compared with conventional tillage. These energy savings ranged from 7 to 11% for cereal crops, whereas for vetch crops the reduction was 10% for minimum tillage and 15% for zero tillage. Production costs for minimum tillage were 13–24% less than for conventional tillage. For zero tillage these reductions ranged from 6 to 17%. For cereal crops, minimum tillage and zero tillage had energy productivities which were 18% and 20%, respectively, greater than that for conventional tillage. In most cases, yields of winter crops were similar, regardless of the tillage system considered. Only spring barley showed lower yields with zero tillage. For winter cereals the profitability with minimum tillage and zero tillage is higher than that with conventional tillage. However, spring barley is less profitable when using zero tillage.     

The decomposition of afterharvest residues in chernozems during the autumn-spring period and in the annual cycle

In the period from September to May, the decomposition of stubble by microorganisms was more active than that during the summer period. The mineralization of stubble of sweet clover, peas, and corn was more active than that of spring wheat, barley, oats, and winter rye. The root residues of the majority of the crops were decomposed slower than the stubble. The yield of the wheat depended on the amount of afterharvest residues, their chemical composition, and the rate of their mineralization. The increase in wheat yields as dependent on the input of the stubble remains of the precursors into the soil can be arranged in the following order: wheat, corn < rye, annual herbs < peas.     

干旱与冬小麦和玉米产量关系的分析

对庆阳地区前一年伏期和秋季、当年春季和春末夏初大气干旱指数与冬小麦和玉米气候产量进行了对比分析和相关分析。结果表明，冬小麦产量与上年秋旱关系最为密切，其次为春旱、春末夏初旱和上年伏旱；玉米产量与当年伏旱关系最为密切，其次为秋旱、春和春末夏初旱。     

Evapotranspiration of irrigated and rainfed maize–soybean cropping systems

We have been making year-round measurements of mass and energy exchange in three cropping systems: (a) irrigated continuous maize, (b) irrigated maize–soybean rotation, and (c) rainfed maize–soybean rotation in eastern Nebraska since 2001. In this paper, we present results on evapotranspiration (ET) of these crops for the first 5 years of our study. Growing season ET in the irrigated and rainfed maize averaged 548 and 482 mm, respectively. In irrigated and rainfed soybean, the average growing season ET was 452 and 431 mm, respectively. On average, the maize ET was higher than the soybean ET by 18% for irrigated crops and by 11% for rainfed crops. The mid-season crop coefficient K_c (=ET/ET₀ and ET₀ is the reference ET) for irrigated maize was 1.03 ± 0.07. For rainfed maize, significant dry-down conditions prevailed and mid-season K_c was 0.84 ± 0.20. For irrigated soybean, the mid-season K_c was 0.98 ± 0.02. The mid-season dry down in rainfed soybean years was not severe and the K_c (0.90 ± 0.13) was only slightly lower than the values for the irrigated fields. Non-growing season evaporation ranged from 100 to 172 mm and contributed about 16–28% of the annual ET in irrigated/rainfed maize and 24–26% in irrigated/rainfed soybean. The amount of surface mulch biomass explained 71% of the variability in non-growing season evaporation totals. Water use efficiency (or biomass transpiration efficiency), defined as the ratio of total plant biomass (Y_DM) to growing season transpiration (T) was 5.20 ± 0.34 and 5.22 ± 0.36 g kg^?1, respectively for irrigated and rainfed maize crops. Similarly, the biomass transpiration efficiency for irrigated and rainfed soybean crops was 3.21 ± 0.35 and 2.96 ± 0.30 g kg^?1. Thus, the respective biomass transpiration efficiency of these crops was nearly constant regardless of rainfall and irrigation.     

Surface soil responses to silage cropping intensity on a Typic Kanhapludult in the piedmont of North Carolina

Although reduced tillage itself is beneficial to soil quality and farm economics, the amount of crop residues returned to the soil will likely alter the success of a particular conservation tillage system within a farm operation. We investigated the impact of three cropping systems (a gradient in silage cropping intensity) on selected soil physical, chemical, and biological properties in the Piedmont of North Carolina, USA. Cropping systems were: (1) maize (Zea mays L.) silage/barley (Hordeum vulgare L.) silage (high silage intensity), (2) maize silage/winter cover crop (medium silage intensity), and (3) maize silage/barley grain—summer cover crop/winter cover crop (low silage intensity). There was an inverse relationship between silage intensity and the quantity of surface residue C and N contents. With time, soil bulk density at a depth of 0–3 cm became lower and total and particulate C and N fractions, and stability of macroaggregates became higher with lower silage intensity as a result of greater crop residue returned to soil. Soil bulk density at 0–3 cm depth was initially 0.88 Mg m⁻³ and increased to 1.08 Mg m⁻³ at the end of 7 years under high silage intensity. Total organic C at 0–20 cm depth was initially 11.7 g kg⁻¹ and increased to 14.3 g kg⁻¹ at the end of 7 years under low silage intensity. Stability of macroaggregates at 0–3 cm depth at the end of 7 years was 99% under low silage intensity, 96% under medium silage intensity, and 89% under high silage intensity. Soil microbial biomass C at 0–3 cm depth at the end of 7 years was greater with low silage intensity (1910 mg kg⁻¹) than with high silage intensity (1172 mg kg⁻¹). Less intensive silage cropping (i.e., greater quantities of crop residue returned to soil) had a multitude of positive effects on soil properties, even in continuous no-tillage crop production systems. An optimum balance between short-term economic returns and longer-term investments in improved soil quality for more sustainable production can be achieved in no-tillage silage cropping systems.     

Changes in N leaching and crop production as a result of measures to reduce N losses to water in a 6‐yr crop rotation

The effects of various measures introduced to increase nitrogen (N)‐use efficiency and reduce N losses to water in a 6‐yr crop rotation (winter wheat, spring barley, green manure, winter wheat, spring barley, spring oilseed rape) were examined with respect to N leaching, soil mineral N (SMN) accumulation and grain yield. An N‐use efficient system (NUE) with delayed tillage until late autumn and spring, direct drilling of winter wheat, earlier sowing of winter and spring crops and use of a catch crop in winter wheat was compared with a conventional system (CON) in a field experiment with six separately tile‐drained plots in south‐western Sweden during the period 1999–2011 (two crop rotation cycles). Total leaching of NO₃‐N from the NUE system was significantly 46 and 33% lower than in the CON system during the first and second crop rotation cycle, respectively, with the most pronounced differences apparently related to management strategies for winter wheat. Differences in NO₃‐N leaching largely reflected differences in SMN during autumn and winter. There was a tendency for lower yields in the NUE system, probably due to problems with couch grass. Overall, the measures for conserving N, when frequently used within a crop rotation, effectively reduced NO₃ concentrations in drainage water and NO₃‐N leaching losses, without severely affecting yield.     

Carbon sequestration by a crop over a 4-year sugar beet/winter wheat/seed potato/winter wheat rotation cycle

A crop managed in a traditional way was monitored over a complete sugar beet/winter wheat/potato/winter wheat rotation cycle from 2004 to 2008. Eddy covariance, automatic and manual soil chamber, leaf diffusion and biomass measurements were performed continuously in order to obtain the daily and seasonal Net Ecosystem Exchange (NEE), Gross Primary Productivity (GPP), Total Ecosystem Respiration (TER), Net Primary Productivity (NPP), autotrophic respiration, heterotrophic respiration and Net Biome Production (NBP). The results showed that GPP and TER were subjected to important inter-annual variability due to differences between crops and to climate variability. A significant impact of intercrop assimilation and of some farmer interventions was also detected and quantified. Notably, the impact of ploughing was found to be limited in intensity (1–2 μmol m^?2 s^?1) and duration (not more than 1 day). Seasonal budgets showed that, during cropping periods, the TER/GPP ratio varied between 40 and 60% and that TER was dominated mainly by the autotrophic component (65% of TER and more). Autotrophic respiration was closely related to GPP during the growth period. The whole cycle budget showed that NEE was negative and the rotation behaved as a sink of 1.59 kgC m^?2 over the 4-year rotation. However, if exports are deducted from the budget, the crop became a small source of 0.22 (±0.14) kgC m^?2. The main causes of uncertainty with these results were due to biomass samplings and eddy covariance measurements (mainly, uncertainties about the u_* threshold determination). The positive NBP also suggested that the crop soil carbon content decreased. This could be explained by the crop management, as neither farmyard manure nor slurry had been applied to the crop for more than 10 years and because cereal straw had been systematically exported for livestock. The results were also strongly influenced by the particular climatic conditions in 2007 (mild winter, and dry spring) that increased the fraction of biomass returned to the soil at the expense of harvested biomass, and therefore mitigated the source intensity. If 2007 had been a ‘normal’ year, this intensity would have been twice as great. This suggests that, in general, the rotation behaved as a small carbon source, which accords with similar studies based on multi-year eddy covariance measurements and export assessment and with modelling or inventory studies analysing the evolution of crop soil organic carbon (SOC) on a decennial scale.     

Influence of organic Crotalaria juncea hay and ammonium nitrate fertilizers on soil nematode communities

Comparisons of organic and inorganic fertilizer effects on nematode communities depend on the specific organic fertilizer used. Field experiments were conducted during 2001 and 2002 in a squash (Cucurbita pepo) agroecosystem to determine if applying sunn hemp (Crotalaria juncea) hay as an organic fertilizer improved nematode communities involved in soil nutrient cycling compared to an equivalent N rate (100 kg N/ha) of ammonium nitrate. Fertilizer source had minimal effect on nematode communities in 2001 when treatments were applied after a winter cover crop of oats (Avena sativa), but differences (P ≤ 0.05) between the fertilizer sources occurred in 2002 when no winter cover cropping preceded squash. Fertilization with sunn hemp hay increased abundance of the bacterivore guilds Ba₁ and Ba₂, and increased fungivores at the end of the experiment. Compared to ammonium nitrate, fertilization with sunn hemp hay resulted in a community with lower maturity index, higher enrichment index, and lower channel index, consistent with a disturbed and nutrient-enriched soil food web undergoing bacterial decomposition. Sunn hemp hay occasionally stimulated omnivorous nematodes, but suppressed plant-parasitic nematodes relative to ammonium nitrate fertilizer. Increasing the sunn hemp hay rate to 200 kg N/ha increased the abundance of bacterivores, fungivores, and predatory nematodes, and total nematode abundance compared to hay at 100 kg N/ha. Fertilization with ammonium nitrate increased the percentage of herbivores, but reduced percentage and abundance of omnivores. In conclusion, sunn hemp fertilizer maintained greater numbers of nematodes involved in nutrient cycling as compared to ammonium nitrate.     

Bound amino acids in humic acids from arable cropping systems

We investigated the varying concentrations of bound amino acids in humic acids (HA) extracted from soils under both crop rotation and continuous cropping of rye. The experiment was created in 1957. Since then, winter rye had been grown continuously and also the sequence of the 7 yr rotation had been started: potato, spring barley, alfalfa, alfalfa, oil seed rape, winter rye, and winter rye. Soils were fertilized with NPK and manure. Continuous cropping of rye increased total acidity of soils and the contents of carboxylic and phenolic groups in HA. The total amounts of the bound amino acids in HA from soils under crop rotation were higher than from continuous cropping of rye. Fertilization with NPK increased the contents of bound amino acids more than manure. Neutral amino acids dominated in all samples of HA, and basic amino acids had the lowest concentrations. In both types of cultivation, glutamic acids, glycine, alanine, valine, and lysine dominated. The proline contents in HA from continuous rye cropping were higher than in HA from soils under crop rotation. The concentrations of β‐alanine and lysine were higher in HA from crop rotation indicating a higher microbial biomass since these compounds are typical constituents of bacteria cell walls.     

Cereal-based wholecrop silages: A potential conservation measure for farmland birds in pastoral landscapes

Declines of farmland birds have been pronounced in landscapes dominated by lowland livestock production and densities of seed-eating birds are particularly low in such areas. Modern livestock production often entails a simple cropping system dominated by ley grassland and maize grown for animal feed. These crops often lack invertebrate and seed resources for foraging birds and can be hostile nesting environments. Cereal-based wholecrop silages (CBWCS) offer potential benefits for farmland birds because they can be grown with minimal herbicide applications and can be spring-sown with following winter stubbles. We compared the biodiversity benefits and agronomic yields of winter-sown wheat and spring-sown barley as alternatives to grass and maize silage in intensive dairy livestock systems. Seed-eating birds foraged mainly in CBWCS fields during summer, and mainly on barley stubbles during winter and this reflected the higher densities of seed-bearing plants therein. Maize and grass fields lacked seed-bearing vegetation and were strongly avoided by most seed-eating birds. Production costs of CBWCS are similar to those of maize and lower than those of grass silage. Selective (rather than broad-spectrum) herbicide application on spring barley crops increased forb cover, reduced yields (by 11%) but caused only a small (<4%) increase in production costs. CBWCS grown with selective herbicide and with following winter stubbles offer a practical conservation measure for seed-eating farmland birds in landscapes dominated by intensively-managed grassland and maize. However, the relatively early harvesting of CBWCS could destroy a significant proportion of breeding attempts of late-nesting species like corn bunting (Emberiza calandra) or yellow wagtail (Motocilla flava). Where late-breeding species are likely to nest in CBWCS fields, harvesting should be delayed until most nesting attempts have been completed (e.g. until after 1st August in southern Britain).     

Changes in the properties of a loamy Gleyic Cambisol as related to the saturation of crop rotations with rape

A direct relationship was found between the saturation of crop rotations with spring and winter rape and the hydrolytic acidity (r = 0.706 and 0.752, respectively), the contents of the mobile (r = 0.708 and 0.901) and total sulfur (r = 0.630 and 0.760), and the humus content (r = 0.449 and 0.467) in a loamy Gleyic Cambisol and its barley yield after sowing of barley for two years (r = 0.604 and 0.612). A high feedback was found between the saturation of the crop rotations with spring and winter rape and the ratio between the contents of humic and fulvic acids (r = ?0.840 and ?0.930, respectively). More intense restoration of the agrochemical properties of the loamy Gleyic Cambisol up to their initial characteristics was shown to take place in the crop rotations with spring rape than in the test with winter rape.     

Cover cropping influences physico-chemical soil properties under direct drilling soybean

In seeking effective methods to prevent soil degradation, conservation tillage plays an important protective role. Apart from significantly reducing production costs, cover crops contributes to beneficial changes in the soil environment. A three-year field experiment included three cover crops (winter rye, winter oilseed rape, and white mustard) subjected to mulching or desiccation and to the action of a herbicide at three rates (100%, 75%, and 50%). The study evaluated soil moisture and the content of organic matter, phosphorus, potassium, and magnesium in two soil layers (0–15?cm and 15–30?cm). Cover cropping had a positive effect on soil organic matter content. More organic matter (by 4.7%) was recorded in the topsoil layer (0–15?cm). Among the cover crops most favorable effect on the content of organic matter in the soil had white mustard (an increase of 14.2%) compared to the control. Moreover, rye and white mustard mulch increased the soil content of phosphorus and magnesium, while oilseed rape mulch increased the potassium content. At the critical growth stages (the flowering/pod set) of soybean (Glycine max (L.) Merril), soil moisture was dependent on mulching treatment and soil layers.     

Tillage and crop management effects on soil erosion in central Croatia

Soil erosion continues to be a primary cause for soil degradation and the loss of soil quality throughout the world. Our objectives were to quantify soil erosion (referred to as erosional drift) and to assign erosion risk to six tillage and crop management treatments evaluated from 1995 to 1999 for a 5-year maize (Zea mays L.), soybean (Glycine hyspida L.), winter wheat (Triticum aestivum L.), oil-seed rape (Brassica napus var. oleifera L.), and spring barley (Hordeum vulgare L.) plus double-crop soybean rotation on Stagnic Luvisols in central Croatia. Standard black fallow (tilled, unsown, and without any vegetative cover) Universal Soil Loss Equation (USLE) plots were used to establish the erosion potential associated with the rainfall pattern for each year. Soil loss from the check plots was several times greater than the T value, which is estimated to be 10 t ha⁻¹ per year. During the 2 years when spring seeded maize or soybean were grown (1995 and 1996) erosion risk was extremely high, especially for treatments where tillage and planting (row direction) were up and down the slope. When autumn seeded winter wheat or oil-seed rape were grown (1996/1997 or 1997/1998), soil erosion was insignificant. Also, except when plowing and sowing were up and down slope, erosion loss for the spring barley plus double-crop soybean crops in 1999 was insignificant. With no-tillage, soil erosion from the maize and soybean crops was reduced 40 and 65% compared to plowing up and down slope, even though the planting direction was still up and down the slope. With the exception of maize in 1995, erosion losses were moderate to insignificant when plowing and planting were performed across the slope. We conclude that erosion risk can be used as a reliable indicator of sustainable land management and that using no-tillage or plowing and planting perpendicular to the predominant slope are effective soil conservation practices for this region.     

Conservation farming strategies in East and Southern Africa: Yields and rain water productivity from on-farm action research

Improved agricultural productivity using conservation farming (CF) systems based on non-inversion tillage methods, have predominantly originated from farming systems in sub-humid to humid regions where water is not a key limiting factor for crop growth. This paper presents evidence of increased yields and improved water productivity using conservation farming in semi-arid and dry sub-humid locations in Ethiopia, Kenya, Tanzania and Zambia. Results are based on on-farm farmer and research managed experiments during the period 1999–2003. Grain yield of maize (Zea mays L.) and tef (Eragrostis Tef (Zucc)) from conventional (inversion) tillage are compared with CF with and without fertilizer. Rain water productivity (WP_rain) is assessed for the locations, treatments and seasons. Results indicate significantly higher yields (p < 0.05) for CF+ fertilizer treatments over conventional treatments in most locations, increasing from 1.2 to 2 t ha^?1 with 20–120% for maize. For tef in Ethiopian locations, the yield gains nearly doubled from 0.5–0.7 to 1.1 t ha^?1 for “best bet” CF+ fertilizer. WP_rain improved for CF+ fertilizer treatments with WP gains of 4500–6500 m³ rainwater per t maize grain yield in the lower yield range from 0 to 2.5 t ha^?1. This is explained by the large current unproductive water losses in the on-farm water balance. There was a tendency of improved WP_rain in drier locations, which can be explained by the water harvesting effect obtained in the CF treatments. The experiences from East and Southern Africa presented in this paper indicate that for smallholder farmers in savannah agro-ecosystems, conservation farming first and foremost constitutes a water harvesting strategy. It is thus a non-inversion tillage strategy for in situ moisture conservation, rather than solely aimed at minimum tillage with mulch cover. Challenges for the future adoption of CF in sub-Saharan Africa include how to improve farmer awareness of CF benefits, and how to efficiently incorporate green manure/cover crops and manage weeds.     

Intercropping winter cereals with Caucasian clover for forage in northern Europe

Intercropping cereal crops with perennial legumes for forage has been demonstrated as a means to improve nutritive value compared to cereal crops alone. Our objective was to determine whether sowing winter rye (Secale cereale L.) or winter triticale (x Triticosecale Wittmack) into living Caucasian clover (Trifolium ambiguum M. Bieb.) improves yield or nutritive value compared to monoculture cereal crop forage in northern Europe. The experiments were conducted near Moche?ek and Fal?cin, Poland. In autumn 2010 and 2011, winter rye was sown into existing Caucasian clover or in monoculture at Moche?ek, and winter triticale was sown into Caucasian clover or in monoculture at Fal?cin, with monoculture clover as a third crop treatment at both locations. The following spring, first harvest of forage from the three crop treatments was taken at two maturities: when monoculture cereals reached heading (BBCH 51) or grain milk stage (BBCH 71), and two additional harvests were taken from mixture plots and monoculture clover before autumn. First harvest forage yields of mixtures were similar to monoculture cereal at Fal?cin, less than monoculture cereal at Moche?ek, and greater than monoculture clover at both locations. Full season forage yields of mixtures were greater than both monoculture cereal and clover crops at both locations. The proportion of clover in mixtures was 20–31% in the first harvest, resulting in slightly lower neutral detergent fiber concentrations than in monoculture cereal crop at Fal?cin, but no improvement in nutritive value at Moche?ek. By spring 2012, most Caucasian clover had died from Sclerotinia trifoliorum infection at both locations, so forage was not harvested in the second year of the experiment. Although total season forage yields were greater for mixtures than for either monoculture cereal or Caucasian clover, this system cannot be recommended for northern Europe because of failure for Caucasian clover to persist.