Relay Intercropping Research Articles

Growing cover crop mixtures are more sustainable than single cover crop in continuous cotton cropping: Comprehensive assessment from 3-year field experiment

Cover cropping combined with nitrogen (N) application reduction is considered as an attractive practice due to increasing resources use efficiency while improving soil health and cash crop productivity. Yet comprehensive assessment studies have rarely been reported from energy, environmental, economic and ecological perspectives under different cover cropping systems. Therefore, a field experiment was conducted during 2019–2022 with four N application rates (i.e., 0 (N0), 112.5 (N1), 168.75 (N2) and 225 (N3, as a control) kg N hm−2) under four cover cropping systems (i.e., continuous cotton (CC), Orychophragmus violaceus with cotton (OC), Vicia villosa with cotton (VC), and an Orychophragmus violaceus and Vicia villosa mixture with cotton (MC) relay intercropping). Field observations were incorporated into a life cycle assessment to evaluate the environmental footprint, energy flow, ecosystem service value and economic and ecosystem economic benefits. Relay intercropping cover crops can reduce the carbon footprint per unit area (CFa) by 36.7%, increase the ecosystem service value by 64.4% and ecosystem economic benefits by 7.8% compared with the CC system, in which MC system had better performance than OC and VC systems at above aspects. N application rates notably increased net energy, CFa, NFa, ecosystem service value, and ecosystem economic benefits. After considering the comprehensive index of energy, environment, the economy and the ecosystem economy, the sustainability performance index of MCN2 (Orychophragmus violaceus and Vicia villosa mixture/cotton relay intercropping with 168.75 kg N hm−2) combination increase by 51.7% compared to all treatments average. Taken together, the study results demonstrated that introducing cover crop mixture into monoculture cotton was more sustainable and cleaner cotton production practice than sing cover crop or fallow in the Yellow River basin and other regions with similar ecological conditions.

Coordinated responses of leaf and nodule traits contribute to the accumulation of N in relay intercropped soybean

Maize (Zea mays L.)–soybean (Glycine max L. Merr.) relay intercropping provides a way to enhance land productivity. However, the late-planted soybean suffers from shading by the maize. After maize harvest, how the recovery growth influences the leaf and nodule traits remains unclear. A three-year field experiment was conducted to evaluate the effects of genotypes, i.e., supernodulating (nts1007), Nandou 12 (ND12), and Guixia 3 (GX3), and crop configurations, i.e., the interspecific row spacing of 45 (I45), 60 (I60), 75 cm (I75), and sole soybean (SS), on soybean recovery growth and N fixation. The results showed that intercropping reduced the soybean total leaf area (LA) by reducing both the leaf number (LN) and unit leaflet area (LUA), and it reduced the nodule dry weight (NW) by reducing both the nodule number (NN) and nodule diameter (ND) compared with the SS. The correlation and principal component analysis (PCA) indicated a co-variability of the leaf and nodule traits in response to the genotype and crop configuration interactions. During the recovery growth stages, the compensatory growth promoted soybean growth to reduce the gaps of leaf and nodule traits between intercropping and SS. The relative growth rates of ureide (RGR_U) and nitrogen (RGR_N) accumulation were higher in intercropping than in SS. Intercropping achieved more significant sucrose and starch contents compared with SS. ND12 and GX3 showed more robust compensatory growth than nts1007 in intercropping. Although the recovery growth of relay intercropping soybean improved biomass and nitrogen accumulation, ND12 gained a more significant partial land equivalent ratio (pLER) than GX3. The I60 treatment achieved more robust compensation effects on biomass and N accumulation than the other configurations. Meanwhile, I60 showed a higher nodule sucrose content and greater shoot ureide and N accumulation than SS. Finally, intercropping ND12 with maize using an interspecific row spacing of 60 cm was optimal for both yield advantage and N accumulation.

Photosynthetic Acclimation of Shade-Grown Soybean Seedlings to a High-Light Environment.

Soybean in relay intercropping is initially exposed to a shade environment, followed by exposure to full sunlight after the harvesting of primary crops, e.g., maize. Therefore, soybean's ability to acclimate to this changing light environment determines its growth and yield formation. However, the changes in soybean photosynthesis under such light alternations in relay intercropping are poorly understood. This study compared the photosynthetic acclimation of two soybean varieties with contrasting shade tolerance, i.e., Gongxuan1 (shade-tolerant) and C103 (shade-intolerant). The two soybean genotypes were grown in a greenhouse under full sunlight (HL) and 40% full sunlight (LL) conditions. Subsequently, after the fifth compound leaf expanded, half of the LL plants were transferred to a high-sunlight environment (LL-HL). Morphological traits were measured at 0 and 10 days, while chlorophyll content, gas exchange characteristics and chlorophyll fluorescence were assayed at 0, 2, 4, 7 and 10 days after transfer to an HL environment (LL-HL). Shade-intolerant C103 showed photoinhibition 10 days after transfer, and the net photosynthetic rate (Pn) did not completely recover to that under a high light level. On the day of transfer, the shade-intolerant variety, C103, exhibited a decrease in net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (E) in the low-light (LL) and low-light-to-high-light (LL-HL) treatments. Additionally, intercellular CO2 concentration (Ci) increased in low light, suggesting that non-stomatal factors were the primary limitations to photosynthesis in C103 following the transfer. In contrast, the shade-tolerant variety, Gongxuan1, displayed a greater increase in Pn 7 days after transfer, with no difference observed between the HL and LL-HL treatments. Ten days after transfer, the shade-tolerant Gongxuan1 exhibited 24.1%, 10.9% and 20.9% higher biomass, leaf area and stem diameter than the intolerant C103. These findings suggest that Gongxuan1 possesses a higher capacity to adapt to variations in light conditions, making it a potential candidate for variety selection in intercropping systems.

Influence of relay intercropping of barley with chickpea on biochemical characteristics and yield under water stress.

Relay intercropping of legumes with cereals is a useful technique for yield increment. Intercropping may affect the photosynthetic pigments, enzyme activity and yield of barley and chickpea under water stress. To investigate the effect of relay intercropping of barley with chickpea on pigment content, enzyme activity and yield under water stress, a field experiment was conducted during 2017 and 2018. The treatments included irrigation regimes (normal irrigation and cutting off irrigation at the milk development stage) as the main plot. Also, cropping systems as sub plot consisted of sole and relay intercropping of barley with chickpea in two sowing dates (December vs January). Under water stress, the early establishment of barley in December intercropped with chickpea in January (b1c2) enhanced the leaf chlorophyll content by 16% compared to sole cropping due to less competition with chickpea. Late sowing of chickpea enhanced the leaf carotenoid content of chickpea, catalase and peroxidase activities. Barley-chickpea intercropping enhanced the WUE and guaranteed a more efficient use of space (land equivalent ratio of more than 1) compared with sole crops. Under water stress, in b1c2 enhancement of total chlorophyll and water use efficiency caused to increase the grain yield of barley. In b1c2, barley and chickpea reacted to water stress with increasing total chlorophyll and enzyme activity, respectively. In this relay intercropping treatment, each crop occupied and used the growth resources from different ecological niches at different times, which is recommended in semi-arid areas.

Relay intercropping cover crop combined with reduced nitrogen application improves subsequent cotton agronomic traits while maintaining yield and quality

AbstractApplying cover crops to reduce nitrogen (N) fertilizer application while ensuring crop productivity is a major challenge for sustainable agricultural production. However, few studies have quantified N fertilizer application reduction through the use of February orchid (Orychophragmus violaceus) cover crops with the goal of ensuring cotton productivity. We conducted field experiments in the Yellow River basin on two cropping systems, monoculture cotton (Gossypium hirsutum L) and cotton/February orchid under four levels of N application (0 [N0], 112.5 [N1], 168.75 [N2], and 225 [N3] kg N·ha−1), to evaluate the impacts of cover cropping on cotton growth parameters, yield, and quality under different N application levels. The results indicated that replacing winter fallow with February orchid prolonged the cotton growth period and increased plant height, leaf area index (LAI), and dry matter accumulation but did not improve cotton yield or fiber quality. The Cotton/February orchid system under a 168.75 kg ha−1 N application rate improved cotton growth, and achieved yield and quality equivalent to those of monoculture cotton under a 225 kg ha−1 N application. Further analysis revealed that February orchid cover crop and N application positively affected lint yield, whereas plant height, LAI, and dry matter accumulation (positively) and phenology (negatively) predicted lint yield and fiber quality. In conclusion, cotton relay intercropping with February orchid in combination with 168.75 kg ha−1 N application is recommended as a suitable cropping system to reduce fallow fields and ensuring cotton productivity in the Yellow River basin and other areas with similar ecological conditions.

Relay intercropping of maize with common dry beans to rationalize nitrogen fertilizer

Maize (Zea mays L.) and dry beans (Phaseolus vulgaris L.) are important staple food and cash crops worldwide. Common bean in an intercrop with maize contributes to biological nitrogen fixation, which stabilize productivity of cropping systems and reduce negative environmental impacts and loss of biodiversity for sustainable agriculture. A field experiments was performed during the years of 2020 and 2021 at Sers El-Layian Station, northern Egypt. The current study aiming to study the effect of three sowing dates of maize, represent 3 co-growth duration [T1: at flowering stage (FS) of common beans (60 days co-growth duration), T2: 15 days after FS (45 days co-growth duration), and T3: 30 days after FS (30 days co-growth duration with beans)] and three N fertilizer levels (N1: 190.4, N2: 238.0, and N3: 285.6 kg N/ha of maize) on productivity, profitability and N fertilizer rationalization. The longest co-growth duration of maize intercropping with common beans (T1) significantly (P ≤ 0.05) decreased common beans and maize yields compared with T2 and T3. Performance of common beans did not show (P ≤ 0.05) any variation under different N fertilizer levels of maize. Significant (P ≤ 0.05) increase in maize yield and its components with raising N fertilizer level up to N3. Although there was no significant variation in maize yield when applied N2 and N3, however, nitrogen use efficiency (NUE) was significant (P ≤ 0.05) higher in N2 than N3 by 18.34%. Regardless of planting time and N fertilizer level of maize, combined productivity of common beans and maize increased in the intercropped system as cleared by higher total land equivalent ratios (LER) and area time equivalent ratios (ATER). Highest LER value 1.99 was observed at the shortest co-growth period T3 under N3 followed by 1.97 with N2. Positive values in the actual yield loss index (AYL) indicated intercropping advantage. Different competition indices showed a greater dominance of maize over common beans (aggressivity, Ag; competitive ratio, CR; actual yield losses, AYL). However, the intercropping systems increased the economic advantage (intercropping advantage index, IAI and monetary advantage index MAI) over monoculture. These results imply that shortening the period of co-growth maize with common beans (T3) and applying 238.0 kg N/ha in the relay intercropping system reduced mineral N fertilizer use by 16.67% compared to the advised level 285.6 kg N/ha along with increased productivity per unit area and economic advantages for small-farmer.

A first-year maize/cassava relay intercropping system improves soil nutrients and changes the soil microbial community in the symbiotic period.

The maize/cassava relay intercropping system can be a specific and efficient cropping pattern in a tropical/subtropical field. Relay intercropping systems contribute to the optimization of land use, fostering sustainable and efficient agriculture. This study entails a first-year comparative intercropping experiment using maize (Zea mays L.) and cassava (Manihot esculenta Crantz). We determined the soil nutrient contents and physicochemical properties as well as the microbial communities by high-throughput sequencing. We found that the relay intercropping system changed the bacterial community structure, especially the rhizosphere microorganisms. The bacterial community was characterized by a higher abundance of the phyla Chloroflexi, Proteobacteria, and Actinobacteria and of the genus AD3, which are related to nutrient cycling and decreased bioavailability of Cd. At the same time, the relay intercropping system reduces the relative abundance of pathogenic bacteria and biomarkers of organic pollution. The relay intercropping systems significantly boosted soil pH and available K levels in addition to the monocropping yield. The results of this study suggest that maize/cassava relay intercropping, starting from the first year, not only provides a stable supply of food and income due to the diversified cropping systems but is also beneficial for the improvement of soil quality and the soil microbial community.

Partial return calculator to compare monocrop, relay‐intercrop, and double crop production systems

AbstractTo improve profitability, farmers are interested in relay intercrop (RI; planting a second crop prior to harvest of the first crop) and double crop (DC; planting a second crop after harvest of the first crop) systems. Economic comparisons can be challenging due to fluctuations in expenses and crop prices. To compare production systems, an Excel‐based partial return calculator was developed. The calculator includes default values for crop yields, expenses, and prices using current information. Additionally, practitioners have the option to enter and use their own values. The objectives of this management guide are to: (a) provide an overview of the calculator; (b) compare partial return of monocrop (MC), RI, and DC production systems; and (c) provide a mechanism for practitioners to use their own values to compare production systems. The partial return calculator compares six production systems, including winter wheat (Triticum aestivum L.) only, wheat + straw harvest, soybean [Glycine max (L.) Merr.] only, wheat (grown in 15‐inch row width) with soybean as a RI, wheat with soybean as a DC, and wheat + straw harvest with soybean as a DC. Partial return for each production system was calculated by subtracting costs (including economic value of P2O5 and K2O removed in harvested portions) from gross return. Using default values, wheat followed by DC soybean and straw harvest resulted in the highest partial return while wheat grown as a MC resulted in the lowest return. Although default values provide a comparison, practitioners should enter their own values to compare production systems.

Orychophragmus violaceus/cotton relay intercropping with reduced N application maintains or improves crop productivity and soil carbon and nitrogen fractions

Orychophragmus violaceus/cotton relay intercropping with reduced N application maintains or improves crop productivity and soil carbon and nitrogen fractions

Effect of row spacing under maize-soybean relay intercropping system on yield, competition, and economic returns

Interrow spacing of intercrop species directly affects yield and competition indices such as land equivalent ratio of intercropping. The objectives of this research were to analyze (i) the maize and soybean yields under different spatial arrangements in maize-soybean relay strip intercropping (MSR) and (ii) the interspecies competition to provide a basis for optimization of rowspacing in MSR. The field trial was conducted in 2011 and 2012 at the Research Farm of the Sichuan Agricultural University in Ya'an to determine the impacts of various interrow planting distances on yield and competition indices in cereal (maize crop)-legume (soybean crop) relay strip intercropping. Three planting arrangements were utilized based on the distance between maize-maize, maize-soybean, and soybean-soybean as (T1) 50, 40, and 70 cm, (T2) 50, 50, and 50 cm, and (T3) 50, 60, and 30 cm, respectively, and comparison was made with the sole maize (SM) and sole soybean (SSB). Experimental results revealed that grain yield of maize crop was improved with enhancing row spaces between maize and soybean, while "low-high-low" trend was observed for soybean yield in T$_{1}$, T$_{2}$, and T3, respectively, in both years. Competitive ratio, aggressivity, and relative crowding coefficient were consistently greater for maize than soybean in all treatments. The highest LER (1.67) was reported in T$_{2}$ treatment, which was 9% and 4% higher than in T$_{1}$ and T$_{3}$, respectively. Higher LER explains that both crops are facilitating each other in a positive way and increase the average net income of T$_{2}$ as compared to T$_{1}$ and T$_{3}$. Enhancing distance between maize-soybean rows with reducing distance between soybean rows put pressure on soybean due to intraspecific competition. Combined results of competitive indices and economic analysis showed that intercrops performed at their maximum in treatment T$_{2}$. Therefore, the maximum intercropping advantages can be achieved by changing the row spacing, which determines the competitive relationship and productivity of MSR.

Effect of different planting pattern arrangements on soil organic matter and soil nitrogen content under a maize/soybean strip relay intercropping system.

Assessing the spatial distribution of organic matter and total nitrogen in soil is essential for management and optimum utilization of fertilizers. Therefore, the present field experiment was conducted to evaluate the impact of different planting pattern arrangements on the spatial distribution of soil total nitrogen and organic matter content under a maize/soybean strip relay intercropping system. The planting was arranged in a manner such that soil sampling could be done from continuous maize/soybean relay strip intercropping (MS1), maize/soybean relay strip intercropping in rotation (MS2), traditional maize/soybean intercropping (MS3), sole maize (M), sole soybean (S), and fallow land (FL) from 2018 to 2020. The results showed significant variations for soil organic matter and total nitrogen content under different planting pattern arrangements of maize and soybean in the strip relay intercropping system. Across all systems, the highest soil organic matter (29.19 g/kg) and total nitrogen (10.19 g/kg) were recorded in MS2. In contrast, the lowest soil organic matter (1.69 g/kg) and total nitrogen (0.64 g/kg) were observed in FL. Soil organic matter and total nitrogen in MS2 increased by 186.45% and 164.06%, respectively, when compared with FL. Soil organic matter and total nitrogen in MS2 increased by 186.45% and 164.06%, respectively, when compared with FL. Furthermore, under MS2, the spatial distribution of soil organic matter was higher in both maize and soybean crop rows as compared with other cropping patterns, whereas the soil total nitrogen was higher under soybean rows as compared with maize in all other treatment. However, correlation analysis of the treatments showed variations in organic matter content. It can be concluded that different planting patterns can have varying effects on soil organic matter and total nitrogen distribution under the strip relay intercropping system. Moreover, it is recommended from this study that MS2 is a better planting pattern for the strip relay intercropping system, which can increase the spatial distribution of soil organic matter and total nitrogen, thereby improving soil fertility, C:N ratio, and crop production. This study will serve as a foundation towards the scientific usage of chemical fertilizers in agricultural sector.

Evaluating water use advantage of wheat/maize relay intercropping under rainfed condition based on same period

Evaluating water use advantage of wheat/maize relay intercropping under rainfed condition based on same period

Screening Soybean for Adaptation to Relay Intercropping Systems: Associations between Reproductive Organ Abscission and Yield

The flower and pod abscission is one of the characteristics of soybean that severely limits yield, especially when intercropped with maize. Therefore, suitable soybean cultivars for intercropping are urgently needed to improve farmland productivity. We conducted a two-year field experiment to evaluate the flower and pod abscission, dry matter production, and yield advantages of 15 soybean cultivars. The results of the principal component analysis (PCA) and cluster analysis (CA) showed that 15 soybean cultivars were classified into three groups, i.e., high-yielding group (HYG), mid-yielding cultivars (MYG), and low-yielding cultivars (LYG). In the HYG group, ND12 and GX3 had characteristics of more flowers and pods and less abscission of flowers and pods. Moreover, the net assimilation rate (NAR) and relative growth rate (RGR) of HYG were significantly higher than the other. The HYG obtained a considerably higher partition ratio of 53% from biomass to seed than the other. Therefore, selecting and breeding cultivars with the characteristics of more flowers and pods and less abscission of flowers and pods can help to increase soybean yield in intercropping.

Cover crops and N fertilization affect soil ammonia volatilization and N2O emission by regulating the soil labile carbon and nitrogen fractions

Introducing cover crops in monocropping systems to improve soil health has been broadly adopted worldwide. However, the impacts of different cover cropping systems on soil emissions and related soil fractions and their regulatory mechanism remain elusive. In this study, four cropping systems, i.e., relay intercropping with Orychophragmus violaceus L./cotton (OvC), Vicia villosa Roth/cotton (VvC), a cover crop mixture (Ov and Vv)/cotton (MSC) and a fallow field–cotton (FFC) system, were combined with four N application rates in a two-rotation cycle (2019–2021) to evaluate the effects on soil greenhouse gases (GHGs) emission, ammonia (NH3) volatilization, and labile carbon (C) and nitrogen (N) fractions and their relationships. Compared with the FFC system, the cumulative NH3 volatilization and nitrous oxide (N2O) emissions of OvC are noticeably reduced 13% and 58%, respectively, and those of VvC are comparable, while those of MSC are markedly increased by 15% and 24%, respectively. N fertilization significantly affects soil NH3 volatilization and N2O emissions, and a higher N rate results in more gaseous N emissions. In addition, NH3 volatilization and N2O emission are positively correlated with the soil microbial biomass N (MBN), dissolved organic N (DON), NH4+-N and NO3--N but negatively correlated with microbial biomass C (MBC) and dissolved organic C (DOC). OvC system decreased gaseous N emission by high soil MBC/MBN ratio, Vv as cover crop indirectly promote soil N2O emission through increased soil MBN, DON and MBC content, while cover crop mixtures increase soil labile C and N fractions and enhance gaseous N emission ultimately. Overall, application of N fertilizer and cover crop mixture both promoted soil NH3 and N2O emissions; the relay intercropping nonlegume cover crop Ov noticeably mitigates N2O and NH3 emissions through an increase in the soil MBC and reduce in the labile N, while introduction of the legume cover crop Vv increases N2O emissions but reduces soil NH3 volatilization due to a lower soil MBC/MBN ratio.

Optimizing maize–bean cropping systems for sustainable intensification in southern Ethiopia

AbstractDeclining productivity and scarcity of cultivable land in smallholder systems call for exploring sustainable intensification options to increase productivity. Field experiments were conducted at five sites (Sites 1–5) of the Sidama region, southern Ethiopia, in 2018 and 2019 to determine the effects of cropping systems on maize (Zea mays L.) and common bean (Phaseolus vulgaris L.) productivity. The intercropping of common bean with maize at varying planting times (simultaneous, relay) and number (frequency) of legume intercropping (once or twice) per growing season were compared with monocultures of the components in randomized complete block design with four replications. Cropping system affected the agronomic parameters (pod number plant−1 and 100‐seed weight) of common bean, more so than maize. Specifically, the results revealed that cropping systems affected both maize and bean yields, although the magnitude of the effect varied with sites. The highest maize yield was recorded in fertilized monoculture maize at Sites 1, 2, and 5, and in relay and sequential bean intercropping at Sites 3 and 4, respectively. Moreover, the highest bean yields were obtained in double common bean monoculture whereas, the lowest yields were recorded in relay intercropping. The total land equivalent ratio (LER) ranged from 1.2 to 1.8 and partial LER of maize was higher than that of the common bean. Sequential intercropping (Sites 1, 2, and 5) and relay intercropping (Sites 3 and 4) were economically more beneficial than the other cropping systems. Therefore, farmers could benefit more from maize–bean intercropping systems than monocultures in areas where maize is a staple crop.

Relay intercropping can efficiently support weed management in cereal-based cropping systems when appropriate legume species are chosen

Relay intercropping of subsidiary legumes with durum wheat (living mulch) can be a viable option to support ecological weed control and optimize nutrient cycling in cereal-based cropping systems. However, the lack of knowledge on suitable legume species is often identified as the main bottleneck for the successful application of legume living mulches. This study aimed to evaluate the suitability of 12 different legumes for relay intercropping with wheat in two contrasting Mediterranean cereal-based cropping systems respectively characterized by low-input and integrated management. Each legume was monitored from the undersowing in wheat until the following spring and we compared direct drilling to broadcast sowing of legumes. None of the undersown legumes showed a negative effect on the wheat grain yield. Relay intercropping of legumes proved to be an effective solution to control weeds before and after the wheat harvest, provided suitable legumes species are chosen. Suitable legumes reduced the weed biomass up to the 90% during the intercropping and up to 94% in the following spring. On the contrary, legumes such as Trifoliumresupinatum, Viciavillosa, Medicagotruncatula, and Medicagoscutellata boosted weed growth in the following spring in comparison with the control. According to the performance of legumes, Medicagosativa, Trifoliumrepens and Medicagolupulina had the most suitable characteristics for relay intercropping with durum wheat at the Ravenna site, in a highly productive region whereas Medicagosativa, Hedysarumcoronarium and Trifoliumsubterraneum performed better in the low-input system near Pisa, where yields are generally lower. This is the first time that such a diversity in legumes species is tested in the same experiment for relay intercropping under diversified environmental and management conditions. The results of this study can support farmers in selecting the most appropriated legume species for their specific cropping systems and local conditions.

Relay Intercropping Winter Cover Crop Effects on Spring Forage Potential of Sweet Maize Stover and Yearling Cattle Beef Performance.

Simple SummaryMaize stover is used globally as winter feed for livestock but the nutritive value is low, requiring supplementation. Small landholders who grow sweet maize for the fresh produce market often also have cattle with little access to winter forage. Grazing cover crops with the stover can potentially increase the available nutritive value. Intercropping the cereal rye or hairy vetch into sweet maize approximately 65 days after planting (V7–9 sweet maize maturity) did not influence sweet maize stover biomass yield or nutritive value after winter. However, the crude protein concentration of hairy vetch was greater than rye, but digestibility was not different. Average daily gains by yearling cattle were similar when grazing maize–rye or maize–vetch. Producers with limited land resources should consider the timing of the spring planting of the primary crop, in this case, sweet maize, in relation to the initiation of grazing of winter cover crops to maximize utilization of the previous crop’s residue (stover) as well as the cover crop itself before the primary crop planting time.Small landholders who grow sweet maize for the fresh produce market often also have cattle with little access to winter forage. Grazing cover crops with sweet maize stover can potentially increase the available nutritive value. A 3-year randomized complete block study with three replicates at New Mexico State University’s Alcalde Sustainable Agriculture Science Center compared sweet maize (Zea mays var. rugosa) with sweet maize relay intercropped at the V7–9 stage with cereal rye (rye: Secale cereale L.) or hairy vetch (vetch: Vicia villosa Roth) for early spring grazing. Intercropping the rye or hairy vetch into sweet maize did not influence the sweet maize stover biomass yield or nutritive value after the winter. The dry matter (DM) yield and crude protein (CP) concentration of hairy vetch biomass was greater (p < 0.01) than rye biomass (1.46 vs. 2.94 Mg DM ha−1 for rye and hairy vetch, respectively, and 145 vs. 193 g CP kg−1 for rye and hairy vetch, respectively). Average daily gains by yearling cattle were not different when grazing maize–rye or maize–vetch. Producers should consider the spring planting timing of the primary crop and the initiation of grazing in the winter or the spring to maximize the utilization of the previous crop’s residue (stover), as well as the cover crop itself.

Yield and intercropping indices of sweet corn and okra grown in young rubber plantation

Intercropping is a labor-intensive practice largely adopted by smallholder farmers to increase yield per unit area, cope with crop failures and market fluctuations, meet food preferences and increase farm income. A field experiment was conducted to examine the yield performances and intercropping efficiencies of sweet corn and okra planted in a young rubber plantation. The treatments were arranged in Randomized Complete Block Design (RCBD) with three replications. The treatments ratios were 20% okra + 80% sweet corn (strip and strip relay intercropping) with sole okra and sweet corn as the control. This consists of strips intercropping (okra and sweet corn planted on the same date), strip relay intercropping (sweet corn planted 4 weeks after okra planting), sole okra and sole sweet corn. The highest yield of okra was obtained from strip relay intercropping while the highest yield of sweet corn was produced from the pattern of strip intercropping. However, the economic analysis showed that the strip intercropping recorded the maximum gross margin and costbenefit ratio of RM 17,733.20 ha-1 and 2.09, respectively. Immature rubber growth was unaffected by intercropping with sweet corn and okra crops. Strip intercropping not only resulted in the higher land equivalent ratio (1.29), but also area time equivalent ratio, % land saved and monetary advantage index of 1.14, 22.28% and RM 7,583.50 ha-1, respectively compared with strip relay intercropping. The highest assessment of intercropping based on relative crowding coefficient was recorded by strip intercropping with 4.56. With regard to competition between the intercrops, okra was a more dominant species as measured by the positive value of aggressivity. However, strip intercropping was indicated the lowest competitive ratio than the strip relay intercropping. Thus, this intercropping pattern could be recommended to the farmers for adoption.

Effects of nutrient uptake and utilization on yield of maize-legume strip intercropping system

<p id="C2">To clarify the difference of nutrient uptake and utilization to yield advantage between maize-soybean relay intercropping and maize-peanut intercropping, we conducted a field experiment for two consecutive years. The results were obtained by comparing nitrogen (N), phosphorous (P), and potassium (K) absorption efficiency and utilization in the intercropping with sole cropping. The results showed that land equivalent ratio (LER) of maize-soybean relay intercropping was 1.16-1.72, which had the advantage of intercropping yield, but the LER of maize-peanut intercropping was 0.89-1.13, which had no obvious yield disadvantage. In maize-soybean relay intercropping system, the amount of N, P, and K uptake was higher than that of the corresponding sole cropping by 32.60%-54.22%, 27.35%-34.64, and 17.74%-24.42%, respectively, but the N utilization efficiency was lower by 21.99%-42.07%. The contributions of the N, P, and K uptake efficiencies to LER were 0.34-0.62, 0.31-0.46, and 0.22-0.32, and the utilization efficiencies contributions were -0.11 to -0.35, -0.03 to -0.31, and -0.11 to 0.22, respectively. In maize-peanut intercropping system, the amount of N, P, and K uptake was higher than that of the corresponding sole cropping by -7.86% to 31.58%, 23.09%-46.52%, and 1.60%-55.48%, respectively, and the N utilization efficiency was higher by 7.55-26.60. The contributions of the N, P and K uptake efficiencies to LER were 0-0.22, 0.05-0.27, and -0.11-0.32, respectively, and the utilization efficiencies contributions were -0.25-0.19, -0.32-0.11, and -0.47-0.32, respectively. In conclusion, yield advantage of maize-soybean relay intercropping was mainly from enhanced nutrient uptake efficiency, but there was no obvious yield advantage in maize-peanut intercropping mainly due to relatively less contribution of nutrient uptake to yield advantage.

Effect of Plant Spacing and N Fertilization Levels of Watermelon Relay Intercropping with Faba Bean in Relation to Yield Productivity

Effect of Plant Spacing and N Fertilization Levels of Watermelon Relay Intercropping with Faba Bean in Relation to Yield Productivity