Years Of Alfalfa Research Articles

Alfalfa Increases the Soil N Utilization Efficiency in Degraded Black Soil Farmland and Alleviates Nutrient Limitations in Soil Microbes

Alfalfa (Medicago sativa L.) can fix N naturally within soils, which makes alfalfa cultivation useful for enhancing soil fertility while minimizing environmental impacts from pesticides, fertilizers, and soil pollution. To assess the influence of alfalfa cropping on degraded black soil, we determined the nutrient stoichiometry of the soil and soil microbial biomass under four corn cultivation systems at the Harbin Corn Demonstration Base (Heilongjiang, China), which is located in Wujia (126°23′ E, 45°31′ N), Shuangcheng district, Harbin, Heilongjiang Province. The cultivation systems included continuous corn cultivation for more than 30 years (CK), 2 years of alfalfa–corn rotation (AC), three years of alfalfa cropping (TA), and four years of alfalfa cropping (FA). Overall, AC, TA, and FA treatment increased the soil pH, reduced the soil salinity, and increased the organic matter content of the 0–15 cm soil layer. TA and FA presented soil nutrient levels comparable to those of degraded cornfields that were fertilized annually. The TA and FA treatments increased the soil available N:P, soil N:P, and soil C:P ratios. Moreover, TA significantly increased the soil microbial biomass P (SMBP) in the 0–15 cm (surface) soil layer and reduced the soil microbial biomass C (SMBC):SMBP ratio. AC, TA, and FA increased the storage and mineralization rates of soil N and alleviated the microbial P limitations in degraded black soil farmland. Compared with FA, TA resulted in greater improvements in the quality of degraded black soil farmland. The ability of alfalfa to enhance soil fertility makes an important component of sustainable agricultural practices aimed at rehabilitating degraded soils.

Assessing the Multifaceted Tradeoffs of Agricultural Conservation Practices on Ecosystem Services in the Midwest U.S.

A comprehensive understanding of the potential effects of conservation practices on soil health, crop productivity, and greenhouse gas (GHG) emissions remains elusive, despite extensive research. Thus, the DeNitrification–DeComposition (DNDC) model was employed to evaluate the impact of eleven commonly practiced management scenarios on ecosystem services in the Western Lake Erie Basin, USA, from 1998–2020. Out of eleven scenarios, eight were focused on corn–soybean rotations with varied nitrogen application timing (50% before planting and 50% at either fall or spring during or after planting), or nitrogen source (dairy slurry or synthetic fertilizer (SF)), or tillage practices (conventional, no-till), or cereal rye (CR) in rotation. Remaining scenarios involved rotations with silage corn (SC), winter crops (CR or winter wheat), and alfalfa. The silage corn with winter crop and four years of alfalfa rotation demonstrated enhanced ecosystem services compared to equivalent scenario with three years of alfalfa. Applying half the total nitrogen to corn through SF during or after spring-planted corn increased yield and soil organic carbon (SOC) sequestration while raising global warming potential (GWP) than fall-applied nitrogen. The no-till practice offered environmental benefits with lower GWP and higher SOC sequestration, while resulting in lower yield than conventional tillage. The incorporation of CR into corn–soybean rotations enhanced carbon sequestration, increased GHG emissions, improved corn yield, and lowered soybean yield. Substituting SF with manure for corn production improved corn yield under conventional tillage and increased SOC while increasing GWP under both tillage conditions. While the role of conservation practices varies by site, this study’s findings aid in prioritizing practices by evaluating tradeoffs among a range of ecosystem services.

Modeling long-term nitrogen utilization under alfalfa–corn rotation in Northeast China

ContextNortheast China is the main commodity grain base in China owing to its intensive corn (Zea mays L.) planting and heavy nitrogen (N) application. Alfalfa (Medicago sativa L.) and corn rotation have the potential to decrease N application and enable efficient N utilization, but its long-term impacts remain unclear. ObjectiveThis study utilized Agricultural Production Systems sIMulator (APSIM) to evaluate the N process of long-term alfalfa–corn rotation, including the soil N status and N legacy benefits of subsequent corn crops, and to optimize alfalfa–corn rotation. MethodsAPSIM was calibrated and validated utilizing datasets of crop N uptake (Nupt), soil inorganic N, and soil total nitrogen (TN) under continuous corn, continuous alfalfa, and rotations of three, four, and five years of alfalfa followed by two years of corn, defined as CC, CA, and 3A2C, 4A2C, and 5A2C treatments, respectively, which were collected from a field experiment in Quanyangou–Lishu, Jilin Province, China during 2014–2022. The validated APSIM was then utilized to simulate long-term (1981–2020) effects on N utilization under CC, 3A2C, 4A2C, and 5A2C treatments at Quanyangou–Lishu, Fujia–Lishu, Chaoyang, and Hailun in Northeast China. ResultsAPSIM effectively simulated the Nupt, inorganic N, and TN, with normalized root mean square errors of 5%–19%, 20%–30%, and 2.0%–4.2%, respectively, between the observed and simulated values. Compared with the CC treatment, alfalfa–corn rotation treatments reduced the N fertilizer application by 143 kg N ha−1 and significantly improved the net N mineralization and Nupt by 41 and 107 kg N ha−1, respectively, achieving increases of 50% and 517% in N use efficiency and N partial factor productivity based on corn equivalent yield, respectively. Alfalfa–corn rotation also consumed 94% of 200–500 cm inorganic N through alfalfa roots absorbing N after 9–14 years, which decreased the risk of soil inorganic N accumulation and N leaching. After 40 years, SON values of alfalfa–corn rotation treatments were 8% and 4% higher in the 0–20 and 20–60 cm soil layers and 1.6% lower in the 60–200 cm soil layer than those of the CC treatment at Quanyangou–Lishu, Fujia–Lishu and Hailun. The SON values of alfalfa–corn rotation treatments were 2.9% lower in three soil layers at 0–200 cm deep relative to those of the CC treatment at Chaoyang, with low precipitation of only 478 mm. Alfalfa–corn rotation also improved the first-year corn yield following alfalfa by 2.3%–8.8% at Quanyangou–Lishu and Fujia–Lishu. ConclusionsThe 4A2C treatment at Quanyangou–Lishu, Fujia–Lishu, and Hailun and the 3A2C treatment at Chaoyang are recommended in Northeast China to increase N use efficiency and N partial factor productivity by decreasing N fertilizer application, increasing SON, and absorbing inorganic N from the 200–500 cm soil layer during the alfalfa growing period and increasing mineral N during the corn growing period. ImplicationsOptimal alfalfa–corn rotations show great potential to reduce soil inorganic N residue and increase N use efficiency and SON in Northeast China.

Effects of planting year of alfalfa on rhizosphere bacterial structure and function

In many areas across the world, alfalfa is still cultivated in the same place over many years, leading to gradually deplete the soil nutrients and increase plant disease and consequent decreases in the yield and quality. Agricultural management practices have been proved to affect largely soil microbial community structure and functions in many reports, but it remains unclear how planting year effects extend to the rhizosphere under a long-term cultivation practices of alfalfa. Exploring such impacts is of great importance to understand and develop plant-microorganism interactions for agricultural sustainability. A long-term field experiment was set up at Linze research station of Lanzhou University in Gansu province, where alfalfa was continuously planted for four years (Y4) and six years (Y6). Rhizosphere soils from two different planting years were collected to examine differences in the bacterial diversity, composition and co-occurrence patterns using 16S rRNA gene sequencing technologies as well as in functional profiles involved in nitrogen cycling predicted by FAPROTAX. We found that soil nutrients including soil organic carbon (SOC), AP (available phosphorus) and nitrate nitrogen (NO3−-N) differed significantly between planting years. Bacterial taxonomic diversity, composition and the relative abundance of functional groups involved in nitrogen cycling were significantly affected by planting years, sampling time and their interactions. Co-occurrence network analysis showed that keystone taxa in both planting years were affiliated to Proteobacteria and bacteria taxa had less complexity and more negative correlations in Y6 than in Y4. NO3−-N was a major factor affecting bacterial community diversity and composition across planting years. Together, our findings suggest that planting years of alfalfa can lead to large variations in soil nutrients and rhizosphere microbial community patterns. These results implies that in agricultural management practices, planting year effects can even extend to microorganisms in association with plant roots, which may affect crop growth given close linkages between rhizosphere processes and plant nutrition availability.

Diversified crop sequencing for suppression of creeping perennial weeds in organic production systems

In the Northern Great Plains, organic production is often limited by creeping perennial weeds. Producers have typically relied on alfalfa to control these weeds but this is not always practical. Therefore, we investigated Canada thistle, field bindweed, and perennial sowthistle suppression from three diversified crop sequences: (i) ALF, three years of alfalfa followed by a fourth year of hard red spring wheat (HRSW); (ii) LENCL, lentil the first year, HRSW interseeded with yellow sweetclover the second year, yellow sweetclover green manure the third year, and HRSW the fourth year; and (iii) CCPLY, nine species cool-season cover crop (CC) polyculture the first year, HRSW the second year, nine-species cool and warm season CC the third year, and HRSW the fourth year. From 2019 to 2021, at peak weed emergence, Canada thistle density declined in ALF, but remained unchanged in LENCL and CCPLY. During peak weed vegetative growth, Canada thistle density in ALF was greatest during 2020 (7 shoots per m−2), then declined during 2021 and 2022 (1 and 0.6 shoots m−2, respectively). Within LENCL, Canada thistle density did not change from 2019 to 2020 (15 and 14 shoots m−2, respectively), but then declined to 0.3 shoots m-2 in 2021 before rebounding again to 5 shoots m−2 in 2022. Within CCPLY, Canada thistle density did not change over time (mean ​= ​9 shoots m−2). Canada thistle biomass at peak weed vegetative growth followed similar patterns. Likewise, ALF was shown to suppress perennial sowthistle and field bindweed more effectively than LENCL or CCPLY. Hence, alfalfa remains a good choice for creeping perennial weed management. However, none of these weed species increased substantially in LENCL and CCPLY, and the final year HRSW yield did not differ among cropping sequences. Therefore, these two sequences may provide crop diversification options along with creeping perennial weed management.

Alfalfa stand age at termination influences soil properties, root characteristics, and subsequent maize yield

Alfalfa (Medicago sativa L.)–maize (Zea mays L.) rotation is an important cropping practice to improve crop production and soil fertility, but the effects of the alfalfa stand age on the performances of the following maize remain unexplored. It is not clear how different alfalfa stand ages at termination influence soil properties, root characteristics, and yield of subsequent maize. The aim of this study was to evaluate how alfalfa influences soil characteristics, which in turn influence the root and aboveground growth and grain yield of the following maize crop. A field experiment from 2014 to 2019 was conducted at the Lishu Experimental Station, Jilin Province, China. The field treatments included six years of continuous maize (CM), six years of continuous alfalfa (CA), three years of alfalfa followed by two years of maize (3A2M), four years of alfalfa followed by two years of maize (4A2M), and five years of alfalfa followed by one year of maize (5A1M). Only the yield for the first-year maize after alfalfa in the 3A2M, 4A2M, and 5A1M treatments significantly increased by 8 %, 23 %, and 13 %, respectively. Root biomass (RB) of CA treatment gradually increased from 2014, reaching its maximum value of 5866 kg ha−1 in 2019, which was 35 % greater than the RB accumulation under CM in the 0–60 cm soil layer. Compared with the CM treatment, 3A2M and 4A2M treatments increased RB, while 3A2M, 4A2M, and 5A2M increased root length density (RLD), root surface area density (RSAD), and root volume density (RVD) of first-year maize after alfalfa. The 4A2M treatment also increased RLD, RSAD, and RVD in the 0–60 cm soil layer of second-year maize and reduced the soil bulk density (BD) in the 0–20 cm soil layer of first-year maize after alfalfa. Only 4A2M and 5A1M treatments significantly increased soil Olsen-P and soil organic carbon by first-year maize after alfalfa. The redundancy analysis results showed that the soil water content in the critical period and soil Olsen-P were the primary factors, which explained 33.8 % and 13.0 % of variation in maize root characteristics (P < 0.01), respectively. Structural equation modeling indicated that sowing alfalfa influenced the subsequent maize yield by influencing the soil Olsen-P, soil mineral nitrogen before sowing, and root characteristics. Therefore, keeping alfalfa for at least four years should be the recommended practice owing to its ability to improve the soil properties, root growth, and subsequent maize yield.

Irrigation and Phosphorus Management of Alfalfa Under Semi-Arid Conditions

The frequency of irrigation and deficit irrigation management are drawing attention because water resources are becoming limited year by year, especially in the last decade. Besides, the rate and application time of P fertilization gained more importance just after the researchers found out it is more effective than N-fertilizing for alfalfa cultivation. This study aimed to determine the effects of different irrigation managements (seasonal deficit, intervals of 5, 7, and 9 days), phosphorus application season (autumn and spring), and the rate of P fertilizer (0, 30, 60, 90 kg ha-1) on the yield and forage quality of alfalfa. The experiment was conducted in the 2019-2020 years, which was the 3rd and the 4th years of alfalfa respectively, under semi-arid Mediterranean conditions. The stand height and fiber content (NDF) were higher in the autumn application. However, forage contained more nitrogen in the spring application. A higher amount of water (800 mm) with higher irrigation frequency (5 days – I5d) caused a reduction in yield due to water excess. The yield was the highest (21.34 t ha-1) and the forage quality was better in 448 mm water application with 9 days intervals (I9d). Seasonal deficit water management caused a significant loss in yield and quality. Nevertheless, 18.04 t ha-1 dry matter yield with 24.05 % CP content was recorded at seasonal deficit water management. P fertilization increased the yield and forage quality. The yield was the highest (20.23 t ha-1) at the rate of 90 kg ha-1 P fertilizer, but yield and forage quality characteristics were similar between 30, 60, and 90 kg ha-1 P. The results showed that P fertilization could be done in both autumn and spring at the rate of 30 kg ha-1 and 448 mm water could be applied at 9 days intervals for fulfilling performance under semi-arid Mediterranean conditions. When water resources are very scarce, the seasonal water deficit should be applied, especially in late summer.

Difference of Bacterial Community Structure in the Meadow, Maize, and Continuous Cropped Alfalfa in Northeast China.

Maize and alfalfa (Medicago sativa L.) have been used extensively in the animal husbandry to compensate for the lack of livestock and fodder yields in the chilly northeast of China. Little is known, however, about the impact on soil characteristics of consecutive plantings in various crops and alfalfa. In this research, the soil characteristics, bacterial community diversity, and structure of the meadow, maize, and alfalfa continuous cropping fields (i.e., 6, 10, 14, 20, and 30 years) were measured. The results showed that maize cropping and continuous cropping of alfalfa increased the soil bacterial alpha diversity compared with meadow cropping, and alpha diversity of alfalfa increased with the continuous planting years. Soil pH, total phosphorus (TP), available P, total potassium (TK), and nitrate nitrogen (NO3–) content were soil variables significantly impacting the structure of soil bacterial communities in different plant types and different alfalfa continuous cropping systems. In addition, the relative abundance of some beneficial microbial species, such as Arthrobacter and Gaiellales, in the cropping maize and continuous cropping of alfalfa was much higher than that in the meadow field. Moreover, the networks differ among different plant types, and also differ among different continuous cropping years of alfalfa, and topologies of the networks suggested that continuous planting of alfalfa promotes cooperation between bacteria, which facilitates the long growth of alfalfa and is beneficial to the soil.

Modeling long-term water use and economic returns to optimize alfalfa-corn rotation in the corn belt of northeast China

The long-term effects of alfalfa (Medicago sativa L.)-corn (Zea mays L.) rotation on soil water use and economic returns have not been evaluated and optimized in the corn belt of northeast China (CBNC). Crop modeling based on long-term weather data and short-term field data helps evaluate agricultural practices’ long-term effect. The Agricultural Production Systems sIMulator (APSIM) was calibrated and validated based on the data sets on soil water storage (SWS), aboveground biomass (biomass), and yield under continuous corn (CC), five years of alfalfa (5A), and three years of alfalfa followed by two years of corn (3A2C) cropping systems from 2014 to 2018 at Quanyangou-Lishu in Jilin province, China. The APSIM could simulate well SWS, evapotranspiration (ET), and annual biomass of alfalfa (5A) with normalized root mean square error (NRMSE) of 9.6%, 5.0% and 13.2%, respectively. This model was also confirmed to simulate well the SWS, ET, yield, and biomass of corn (CC) with the NRMSE of 9.6%, 3.4%, 6.5% and 9.8%, respectively and that of alfalfa-corn rotation (3A2C) with the NRMSE of 8.4%, 4.5%, 8.7% and 12.2%, respectively. The validated APSIM was used to optimize the alfalfa-corn rotation systems by simulating water use and economic returns under five scenarios, including CC, 3A2C, four years of alfalfa followed by two years of corn (4A2C), five years of alfalfa followed by two years of corn (5A2C) and five years of alfalfa followed by five years of alfalfa (5A5A) based on the weather data from 1984 to 2018 (35 years) at Quanyangou-Lishu (black soil with losing mollic epipedon, relatively warm and moist climate, in Jilin province, the center of CBNC), Fujia-Lishu (aeolian sandy soil, relatively warm and moist climate, in Jilin province), Chaoyang (cinnamon soil, warm and dry climate, in Liaoning province, the south of CBNC) and Hailun (black soil with moderately thick mollic epipedon, cold and wet climate, in Heilongjiang province, the north of CBNC). Dry soil layers were only found in 250–400 cm soil layer in 18-yr 5A5A or 20-yr 5A2C treatment at Chaoyang and in 350–450 cm soil layer in 20-yr 5A5A or 26-yr 5A2C treatment at Quanyangou-Lishu. At four sites, the highest and lowest mean annual biomass water use efficiency (WUEB) could be found in CC (30.91–38.93 kg ha−1 mm−1) and in 5A5A (20.53–26.31 kg ha−1 mm−1), respectively. The alfalfa-corn rotation treatments had similar WUEB ranged from 22.91 to 30.17 kg ha−1 mm−1. The NR of alfalfa-corn rotation treatments at four sites were 38–169% higher than that of CC and 6–35% lower than that of 5A5A. Alfalfa-corn rotation treatments improved the stability of NR at Fujia-Lishu and Chaoyang by the CV of 40–75% and 65–95%, compared to that of CC treatment by the CV of 79% and 101%, respectively. Among alfalfa-corn rotation treatments, the 5A2C had higher and more stable NR than 4A2C and 3A2C. Therefore, we suggested 5A2C at Fujia-Lishu and Hailun and 4A2C at Quanyangou-Lishu and Chaoyang to achieve dry soil layer’s prevention, relatively high WUEB and high and stable NR.

Alfalfa-corn rotation and row placement affects yield, water use, and economic returns in Northeast China

Planting systems in the corn belt of Northeast China (CBNC) have been adjusted to solve the problem of black soil productivity decline caused by long-term intensive cultivation. To this end, field experiments with the alfalfa (Medicago sativa L.)-corn (Zea mays L.) rotation and row placement were conducted to evaluate soil water, crop yield, and economic returns in the CBNC from 2014 to 2018. The three treatments included continuous corn (CC), continuous alfalfa (CA), and three years of alfalfa followed by two years of corn (3A2C). Corn was planted in the row (R) or interrow (IR) space of the previously planted alfalfa in the 3A2C treatment in 2017 and 2018. Planting alfalfa increased farmer income, and the 5-yr total revenue of the CA treatment was 41% greater than that of the CC treatment. There was no difference in total evapotranspiration (ET) between the CC and CA treatments, and the 5-yr biomass water use efficiency (WUEB) of the CA treatment decreased by 48%, compared with that of the CC treatment. The 3A2C treatment increased corn leaf area index, biomass, and yield. Corn yield of the 3A2C treatment was 8% greater than that of the CC treatment in 2017. The 5-yr net revenue of the 3A2C treatment increased by 24% compared with that of the CC treatment. Corn planting in the first year after alfalfa removal reduced ET. The ET of the 3A2C treatment decreased by 12% in 2017 compared with that of the CC treatment, The WUEB of the 3A2C treatment was 18% and 14% greater than that of the CC treatment in 2017 and 2018, respectively. Corn planted into the previously planted alfalfa row produced 4% and 6% greater yield and 12% and 18% greater WUEB than corn planted in the interrow space in 2017 and 2018, respectively. Therefore, an alfalfa-corn rotation system suitable for use in the CBNC and found to economically benefit farmers consisted of three years of alfalfa followed by two years of corn planted in the previous alfalfa crop row (3A2C-R).

FOLIAR APPLICATION OF SELENIUM, ZINC AND COPPER IN ALFALFA (Medicago sativa L.) BIOFORTIFICATION

Biofortification of forage crops has an important role in improving the quality of plants used for animal nutrition. The field experiments were conducted in three consecutive years in Subotica, Serbia, in order to investigate the effect of Se, Zn, and Cu foliar fertilization on the yield, Se and Zn contents and nutrient efficiency, as well as on other mineral compositions of alfalfa hay. The treatments were as follows: i) control without fertilization, ii) 5 g Se ha-1, iii) 10 g Se ha-1, iv) 0.5 kg Zn ha-1, v) 1 kg Zn ha-1, vi) the combination of these two elements (0.5 kg Zn ha-1 and Se 10 g ha-1) and vii) 2% Cu solution. The application of Se, Zn, and Cu had no effect on dry yield or on crude protein, P, K, Ca, Mg, Fe, Mn, Mo, and Co contents in alfalfa hay. However, Se, Zn, and Cu fertilization significantly increased the contents of Se, Zn, and Cu in alfalfa hay. The results showed that Se and Zn contents in plant biomass were significantly correlated with the applied doses of Se (r=0.99) and Zn (r=0.99). The production years of alfalfa and the weather conditions proved to be significant factors in fertilization efficiency.

Soil organic matter dynamics under irrigated perennial forage–annual crop rotations

AbstractReduced soil disturbance and increased organic matter inputs in forage production systems may improve soil quality and crop production through their effects on soil organic matter (SOM) dynamics and nutrient cycling. We evaluated the effects of conventional (CV), organic (OR) and reduced‐tillage (RT) management systems on SOM pools in perennial forage–annual crop rotations established on soils previously under long‐term monocropped corn (Zea mays L.) field. The SOM pools evaluated include potentially mineralizable carbon (PMC) and nitrogen (PMN), dissolved organic carbon (DOC) and nitrogen (DON), microbial biomass carbon (MBC) and nitrogen (MBN), inorganic nitrogen (inorganic‐N), soil organic carbon (SOC) and soil total nitrogen (STN). The crop rotation was 3 years of alfalfa (Medicago sativa L.)–grass mixture (2009‐2011) followed by a fourth year of corn (2012) across all management systems. While soils under the RT system had the highest rate of labile carbon (C) and nitrogen (N) accrual, all management systems accumulated SOC and STN during 2009‐2011. The response of different C and N pools was not consistent in 2012 when the fields were transitioned from alfalfa‐grass mixture to corn production. Soil PMN and inorganic‐N contents were significantly greater under CV than other management systems, whereas PMC and MBC remained greater under RT than other management systems. This suggests CV may provide immediate benefits to crop production by increasing N availability, but RT has potential to increase SOC accumulation and improve soil quality in the long‐term under perennial forage–annual crop rotations.

Optimizing Iowa land use: Past perspectives for current questions

Multiple tools exist today to guide sustainable land use, including soil maps, market analysis, and producer input, but we often forget they were also available in the past. During the 1930s hundreds of Iowa farmers met to discuss how to maintain productivity and reduce soil erosion. This review, based on three Iowa State University library sources that compiled county agricultural planning committee activities, provides useful perspectives for current agricultural land use questions. Ninety-seven percent of the committees concluded that less than half of the farmers in their respective areas were using land-improving practices, although 41% thought soil conservation and erosion control could be adequately addressed through individual actions. Corn (<i>Zea mays</i> L.) and soybean (<i>Glycine max</i> [L.] Merr.) were planted on 600,000 ha more than they recommended, while grasslands were grown on 900,000 fewer ha. The agricultural committees recommended rotations that most commonly included four crops but ranged from one (monoculture) to eight. Their discussions included recommendations for which crops were best for various soil series and/or landscape positions. There were no identifiable differences in crop rotation length across landscape position, with the most common rotation (45%) being two years of corn, followed by oat (<i>Avena sativa</i> L.), and then one or more years of alfalfa (<i>Medicago sativa</i> L.). Crop production practices have changed since the 1930s. However, reexamining these discussions echoes contemporary soil and water conservation conversations and aligns with farmer response data regarding improving soil productivity, reducing nutrient losses, and maintaining economic vitality.

Yield and Uptake of Phosphorus by Wheat and Canola Grown after Two Years of Forage Legume and Annual Crops

Annual legumes have been shown to enhance the growth and phosphorus (P) uptake by following rotational crops. However, there is lack of information on the effect of perennial forage legumes included in rotation for a short duration on yield and P uptake of crops like wheat (Triticum aestivum L.) and canola (Brassica napus L.) grown after the forage legume. A field study was conducted in four soil zones of Saskatchewan, Canada to assess: 1) the effect of two years of forage legume versus annual cereal, oilseed and grain legume on yield and P uptake of wheat and canola grown in the two subsequent years and 2) the effect of the complete four-year rotation on soil P dynamics and P balance. Four different crop sequences (alfalfa-alfalfa, red clover-red clover, barley-pea and barley-flax) employed over the first two years of crop rotation were compared as treatments followed by wheat and canola. Wheat grain yield was improved 32% - 60% by alfalfa (Medicago sativa L.) and red clover (Trifolium pretense L.) rotations at three of the four sites (P = 0.008, P = 0.001, P - 43% by red clover and alfalfa rotation at two sites (P = 0.013, P = 0.033). In the following year, positive yield benefits (55% - 64%) of having two years of alfalfa and red clover were observed at three sites. Four years of continuous cropping with a limited addition of fertilizer P resulted in a negative soil P balance and significant depletion of soil P fertility at all locations.

Nitrogén, réz és molibdén kölcsönhatások lucerna kultúrában (Medicago sativa L.)

Interactions between the elements N, Cu and Mo were studied on alfalfa in 1996-1999 in a field experiment set up on chernozem loam soil with lime deposits. The ploughed layer of the soil contained 3% humus, around 5% CaCO3 and around 20% clay. Soil analysis showed that the area was well supplied with Ca, Mg, K and Mn had satisfactory Cu content, but was only poorly or moderately supplied with P and Zn. The groundwater depth was 13–15 m and the area was prone to drought. The experiment was originally set up in a split-plot design with 4N × 3Cu = 12 treatments in three replications, giving a total of 36 plots. The N rates, applied as calcium ammonium nitrate, were 0, 100, 200 and 300 kg·ha−1 and the Cu rates, in the form of CuSO4, were 0, 50 and 100 kg·ha−1. In the 5th year of the experiment the 15 m long plots were halved and the two half-plots were separated by a 1 m path. The experiment thus became a strip-split-plot design, consisting of 4N×3Cu×2Mo = 24 treatments in three replications, giving a total of 72 plots. The 48 kg·ha−1 Mo was applied in the form of (NH4)6Mo7O24·4H2O. The main results were as follows: In this chernozem loam soil the N, Cu, Mo treatments did not affect the yield of alfalfa. During the four years studied (1996–1999), a total of 32 t·ha−1 of hay was harvested, with maximum yields (4–5 t·ha−1) at the first mowing. Considering the years, the 2nd year of alfalfa was the most successful with a yield of 11 t·ha−1.With increasing rates of N, the incorporation of N, NO3-N, Ca, Mg, Na, and sometimes Cu increased, while that of K decreased in the hay. Due to the 10–12-year residual effect of CuSO4 the original Cu content of the hay improved by 30–50%, i.e. 2–4 mg·kg–1.A single dose of 48 kg·ha−1 Mo raised the hay Mo content by an order of magnitude to 18–69 mg·kg–1 even after 5–8 years. The Mo content decreased with age and the number of mowings. Nevertheless, the hay became unsuitable for use as animal feed. Mo fertilization also influenced the incorporation of other elements, demonstrably increasing the uptake of N, Ca and Mg and moderating that of K, NO3-N and Cu.As a specific catalyst for the N-binding microorganisms in the soil, Mo is able to increase the soil N supply and thus the N content of the plants. Mo is also necessary for NO3 reduction, so the quantity of NO3-N is reduced through incorporation into proteins in response to Mo. In the present experiment, N-Mo and N-Cu synergism and Mo-NO3 antagonism were manifested.Due to the influence of the different years, mowings and treatments, the minimum and maximum element contents of the hay varied over a wide range. In 12 mowings over the course of four years a total of 1190 kg N, 787 kg K, 768 kg Ca, 154 kg Mg, 128 kg S, 102 kg P, 12 kg Na, 8 kg Fe, 5 kg Al, 4 kg Sr and 2 kg each of Mn and B was taken up per hectare, together with 416 g Zn, 288 g Ba, 256 g Cu and 96 g Mo per ha. The uptake of Mo was 1131 g·ha−1 on Mo-treated soil.The specific nutrient content of 1 t hay was 37 kg N, 25 kg K, 24 kg Ca, 5 kg Mg and 3 kg P (7 kg P2O5). N abundance was associated with elevated specific nutrient content under the given experimental conditions. On this soil atmospheric N fixation was able to cover the N requirements of alfalfa.

Strip-tillage reduces productivity in organically managed grain and forage cropping systems in the Upper Midwest, USA

AbstractTillage is decreasing globally due to recognized benefits of fuel savings and improved soil health in the absence of disturbance. However, a perceived inability to control weeds effectively and economically hinders no-till adoption in organic production systems in the Upper Midwest, USA. A strip-tillage (ST) strategy was explored as an intermediate approach to reducing fuel use and soil disturbance, and still controlling weeds. An 8-year comparison was made between two tillage approaches, one primarily using ST the other using a combination of conventional plow, disk and chisel tillage [conventional tillage (CT)]. Additionally, two rotation schemes were explored within each tillage system: a 2-year rotation (2y) of corn (Zea mays L.), and soybean (Glycine max [L.] Merr.) with a winter rye (Secale cereale L.) cover crop; and a 4-year rotation (4y) of corn, soybean, spring wheat (Triticum aestivum L.) underseeded with alfalfa (Medicago sativa L.), and a second year of alfalfa. These treatments resulted in comparison of four main management systems CT-2y, CT-4y, ST-2y and ST-4y, which also were managed under fertilized and non-fertilized conditions. Yields, whole system productivity (evaluated with potential gross returns), and weed seed densities (first 4 years) were measured. Across years, yields of corn, soybean and wheat were greater by 34% or more under CT than ST but alfalfa yields were the same. Within tillage strategies, corn yields were the same in 2y and 4y rotations, but soybean yields, only under ST, were 29% lower in the fertilized 4y than 2 yr rotation. In the ST-4y system yields of corn and soybean were the same in fertilized and non-fertilized treatments. Over the entire rotation, system productivity was highest in the fertilized CT-2y system, but the same among fertilized ST-4y, and non-fertilized ST-2y, ST-4y, and CT-4y systems. Over the first 4 years, total weed seed density increased comparatively more under ST than CT, and was negatively correlated to corn yields in fertilized CT systems and soybean yields in the fertilized ST-2y system. These results indicated ST compromised productivity, in part due to insufficient weed control, but also due to reduced nutrient availability. ST and diverse rotations may yet be viable options given that overall productivity of fertilized ST-2y and CT-4y systems was within 70% of that in the fertilized CT-2y system. Closing the yield gap between ST and CT would benefit from future research focused on organic weed and nutrient management, particularly for corn.

Converting perennial legumes to organic cropland without tillage

AbstractOrganic producers are interested in developing a no-till system for crop production. In this study, we examined management tactics to convert perennial legumes to annual crops without tillage. Our hypothesis was that reducing carbohydrate production in the fall by mowing would favor winterkill. Mowing treatments were imposed in the fall of the third year of alfalfa or red clover, and corn planted in year 4. The conventional practice of tillage to convert legumes to cropland was also included as a treatment. Mowing in autumn reduced red clover biomass 93% compared with alfalfa when measured 3 weeks after corn planting (WAP). Red clover biomass was still 75% less than alfalfa 6 WAP. Fall mowing suppressed red clover sufficiently to enable corn seedlings to establish, but corn seedlings did not survive in mowed alfalfa due to alfalfa competition. Corn grain yield following red clover was similar in the mowed and tilled treatments when weeds were present. Late season clover and weed growth reduced corn yields 46% compared with weed-free corn. Weed emergence in corn was three times higher after tillage compared with the mowed treatment. Converting red clover to annual crops with fall mowing will support a no-till system for organic farming.

Surface water quality and cropping systems sustainability under a changing climate in the Upper Mississippi River Basin

Agricultural nonpoint source pollution is the main source of nitrogen (N) and phosphorus (P) in the intensely row-cropped Upper Mississippi River Basin (UMRB) stream system and is considered the primary cause of the northern Gulf of Mexico hypoxic zone according to the US Environmental Protection Agency. A point of crucial importance in this region is therefore how intensive corn (<i>Zea mays</i> L.)-based cropping systems for food and fuel production can be sustainable and coexist with a healthy water environment, not only under existing climate conditions but also under a changed climate in the future. To address this issue, a UMRB integrated modeling system has been built with a greatly refined 12-digit subbasin structure based on the Soil and Water Assessment Tool (SWAT) water quality model, which is capable of estimating landscape and in-stream water and pollutant yields in response to a wide array of alternative cropping and/or management strategies and climatic conditions. The effects of the following four agricultural management scenarios on crop production and pollutant loads exported from the cropland of the UMRB to streams and rivers were evaluated: (1) expansion of continuous corn across the entire basin, (2) adoption of no-till on all corn and soybean (<i>Glycine max</i> L.) fields in the region, (3) substitution of the traditional continuous corn and corn–soybean rotations with an extended five-year rotation consisting of corn, soybean, and three years of alfalfa (<i>Medicago sativa</i> L.), and (4) implementation of a winter cover crop within the baseline rotations. The effects of each management scenario were evaluated both for current climate and a projected midcentury (2046 to 2065) climate from a General Circulation Model (GCM). All four scenarios behaved similarly under the historical and future climate, generally resulting in reduced erosion and nutrient loadings to surface water bodies compared to the baseline agricultural management. Continuous corn was the only scenario which resulted in increased N pollution while no-till was the most environmentally effective and able to sustain production at almost the same levels. Rye (<i>Secale cereale</i> L.) cover crop within the fallow period was also effective in reducing erosion and both sediment-bound and soluble forms of nutrients. The results indicated that alternative management practices could reduce sediment, N, and P exports from UMRB cropland by up to 50% without significantly affecting yields. Results for the climate change scenario showed that the effectiveness of the management scenarios was strongly linked to the reduced water availability predicted under the future climate, which assisted in mitigating pollutant transport, although with a small loss of production.

Potassium Management during the Rotation from Alfalfa to Corn

High K fertilizer prices in recent years have made it imperative for growers to apply optimum K rates to alfalfa (Medicago sativa L.). Current university fertilizer guidelines in the Corn Belt do not change for the last production year, when alfalfa stand persistence is not a major concern. Furthermore, little is known about carryover of K applied to alfalfa on first‐year corn (Zea mays L.) grain and silage yields. In 2008 to 2010, on‐farm research was conducted on 10 fields with medium soil test potassium (STK) to determine response to K for alfalfa yield and quality in the last production year, and to estimate K carryover to first‐year corn. Alfalfa yield and relative feed value (RFV) and quality (RFQ) did not improve with K fertilization. Herbage K concentration and K uptake increased with K fertilization across sites, indicating that applied K was available during the season of application. When corn relied on carryover K alone, each 100 kg ha−1 increase in the index of available K increased corn grain yield by 0.5 Mg ha−1, decreased stover yield by 0.4 Mg ha−1, and did not affect silage yields. Regardless of K rate applied to alfalfa, additional K applied to corn increased corn stover and silage yields by 10 and 8%, respectively. This suggests that carryover K was less available than K applied to corn. On medium STK soils going into the last year of alfalfa, applying fertilizer K to first‐year corn rather than alfalfa may enhance economic return.

Evidence of improved water uptake from subsoil by spring wheat following lucerne in a temperate humid climate

Dry spells during the summer period affecting water uptake and plant growth in central Europe may occur more frequently in the future due to climate change. Improving the ability of crops to take up water from deeper soil layers is a potential strategy to secure water supply. The objective of this paper is to report on the effect of different preceding fodder crops on root growth and water uptake of spring wheat from the subsoil. Water extraction and root length density during grain filling of spring wheat were observed between anthesis and maturity in six different soil depths (0–15, 15–45, 45–60, 60–75, 75–90 and 90–105 cm) and with four different preceding crops: 1 year of fescue (Fes1Y), 2 years of chicory (Chi2Y), 2 years of lucerne (Luc2Y) and 3 years of chicory (Chi3Y). While there was no difference in total water extraction by wheat in the four crop sequences, water extraction from the deepest layer (90–105 cm) was significantly higher after 2 years of lucerne (Luc2Y). This was consistent with the root length densities measured in the 90–105 layer, which were 82, 89 and 112% higher in Luc2Y as compared to Fes1Y, Chi2Y and Chi3Y, respectively. Results suggest that lucerne as preceding crop supports deeper rooting and higher rooting density of following spring wheat enhancing access to water in deeper soil layers in response to prolonged dry spells. Effects facilitating root penetration like improved soil structure and higher nitrogen availability after lucerne are discussed. We conclude that suitable crop rotations with lucerne might be a cost-effective adaptation measure to overcome drought stress.