15N studies on the transfer of legume-fixed nitrogen to associated cereals in intercropping systems

Summary An attempt has been made to estimate quantitatively the amount of N fixed by legume and transferred to the cereal in association in intercropping systems of wheat (Triticum aestivum L.) — gram (Cicer arietinum L.) and maize (Zea mays L.) —cowpea (Vigna unguiculate L.) by labelling soil and fertilizer nitrogen with ¹⁵N. The intercropped legumes have been found to fix significantly higher amounts of N as compared with legumes in sole cropping if the intercropped cereal-legume received the same dose of fertilizer N as the sole cereal crop. But when half of the dose of the fertilizer N applied to sole cereal crop was received by intercropped plants, the amount of N fixed by legumes in association with cereals was significantly less than that fixed by sole legumes. Under field conditions 28% of the total N uptake by maize (21.2 kg N ha^–1) was of atmospheric origin and was obtained by transfer of fixed N by cowpea grown in association with maize. Under greenhouse conditions gram and summer and monsoon season cowpea have been found to contribute 14%–20%, 16% and 32% of the total N uptake by associated wheat and summer and monsoon maize crops, respectively. Inoculation of cowpea seeds with Rhizobium increased both the amount of N fixed by cowpea and transferred to maize in intercropping system.     

Estimated yield and nutrient contributions of legume cover crops intercropped with yam,cassava, and maize in the Benue River basins of Nigeria

Intercropping trials were established in the sandy soils of the Benue River Basins of Nigeria to assess the effect of some food legumes used as cover crops in cassava, yam, and maize based cropping systems. The soil productivity and yield contributions of ground akidi (Sphenostylis stenocarpa), pigeon pea (Cajanus cajan), local (Kafanji), and improved (IAR‐355) cowpea (Vigna unguiculata) varieties to the main crops were assessed and presented on a fertilizer‐ equivalent basis. The cowpea varieties and ground akidi helped maize to increase the efficiency of nitrogen (N)‐phosphorus (P)‐potassium (K) fertilizer use by producing an additional 2.74 and 1.59 kg grains/kg, respectively. While an additional six tons of yam tubers was contributed by the kafanji intercrop per hectare, only about three tons was contributed by ground akidi. With the exception of pigeon pea, the test legumes were suitable for use as cover crops for cassava, yam, and maize in the Benue River Basins of Nigeria.     

坡耕地甜玉米地膜覆盖间作模式水土保持效应

针对云南省山地种植措施不合理,水土资源流失严重的现状,进行了甜玉米间作草带和辣椒的水土保持效应研究。结果表明,在降雨集中的6,7,8这3个月,间作处理的径流量比单作处理的径流量平均减少了29.08%,侵蚀量平均减少了52.36%。B处理(甜玉米盖膜+牧草)的总径流量比D处理(辣椒单作)减少了85.05%,B处理的总侵蚀量比C(甜玉米盖膜单作),D处理分别减少了62.58%,63.34%。在极高雨强下,B处理的径流量比D处理减少了75.29%,B处理的侵蚀量比C,D处理的分别减少了81.36%,98.34%。可见,甜玉米间作牧草草带是一种持续利用和保护山地水土资源的有效措施。     

玉米/大豆和玉米/甘薯模式下玉米干物质积累与分配差异及氮肥的调控效应

【目的】西南山地玉米区是我国第三大玉米主产区,但单产比全国低近750 kg/hm2。由于该区特殊的气候条件,玉米以多熟间套种植为主,如何利用多熟种植中各作物的间套优势和茬口特性,寻求提高本区玉米产量的新途径,是农业科技工作者研究的热点。本文在四川的两个玉米主产区,通过四年的田间小区试验,对比研究了西南玉米主要的两种套作模式—玉米/大豆和玉米/甘薯模式下玉米干物质积累分配、转运差异及施氮量对其的调控效应,以探讨种植模式和氮肥管理的增产效应。【方法】2008年设置玉米/大豆和玉米/甘薯两个套种田间试验,分析比较两种模式玉米干物质积累、分配和转运的差异;2009 2010年在前一年的基础上分带轮作,即玉米分别种在大豆或甘薯茬上,分析套作和轮作效应对玉米干物质积累的影响;2011年,在前三年的基础上,采用小区套微区的方式,研究两种模式下不同施氮水平(N0、N90、N180、N270、N360)对玉米干物质积累和转运的调控。【结果】1)在玉米/大豆模式下,玉米干物质积累量从蜡熟期开始显著高于玉米/甘薯模式,茎鞘输出率也显著高于玉米/甘薯模式,最终产量增加2.4%3.2%,但差异未达显著水平;2)分带轮作后,从拔节期开始,玉米/大豆模式下玉米干物质积累量就显著高于玉米/甘薯模式,到成熟期两套种模式下玉米单株干物质积累两试验点平均相差达26.8 g,茎秆向籽粒的输出率和贡献率也显著高于玉米/甘薯模式,收获指数玉米/大豆模式平均较玉米/甘薯模式提高3.9%,最终玉米/大豆模式下玉米产量较玉米/甘薯模式增幅加大,两年两个试验点分别增加了7.4%和14.4%;3)氮肥对两种模式下玉米干物质积累分配和产量的调控效应显著,玉米/大豆模式下,玉米以施氮180kg/hm2处理,而玉米/甘薯模式下270 kg/hm2处理与同一模式下其他氮素水平相比,增加了光合产物的积累,提高了干物质增长速率,延长了灌浆持续天数,有利于茎鞘和叶片的干物质向籽粒转移,显著提高收获指数,进而提高玉米的增产潜能,玉米/大豆模式下低氮处理(0 180 kg/hm2)对玉米的增产效应比较明显,在高施氮水平(270360 kg/hm2)下两种模式间玉米产量差异不显著。【结论】西南丘陵旱地应选择玉米与大豆套作,采用分带轮作种植方式,既有利于提高玉米产量,又可避免大豆的连作障碍;且氮肥管理措施应因种植模式不同而有所差异,在中高等肥力条件下,与大豆套作玉米施氮180 kg/hm2,与甘薯套作施氮应提高至270 kg/hm2。     

Effects of Nitrogen and Phosphorus Fertilizers and Intercropping on Uptake of Nitrogen and Phosphorus by Wheat,Maize, and Faba Bean

Abstract

One‐third of all the cultivated land area is used for multiple cropping and half of the total grain yield is produced with multiple cropping in China. There have been numerous studies on nutrient acquisition by crops in legume/non‐legume intercropping systems, but few on nutrient uptake in cereal/cereal intercropping. This paper describes a field experiment in which integrated wheat/maize and maize/faba bean systems were compared with sole wheat and sole faba bean cropping to assess the effects of intercropping on nutrient uptake by wheat, maize, and faba bean under various application rates of nitrogen (N) and phosphorous (P) fertilizers. Results show that both N and P fertilizers and intercropping enhanced N uptake by wheat, while only P fertilizer and intercropping increased P acquisition by wheat. The advantage of N uptake by border rows of wheat intercropped with maize declined with increasing N fertilizer application rate, but that of P acquisition was not affected by P fertilizer. The amounts of both N and P taken up by maize intercropped with faba bean were much higher than those by maize intercropped with wheat throughout the period of intercropping. Both fertilization and intercropping did not influence the N and P uptake by faba bean.     

Effect of phosphorus fertilizer application on the performance of maize/soybean intercrop in the southern Guinea savanna of Nigeria

Field experiments were conducted at the Teaching and Research Farm, Ladoke Akintola University of Technology, Ogbomoso, Nigeria in 2007 and 2008 to determine the effects of phosphorus fertilizer application on performance of intercropped maize and soybean. The experiments, arranged as a split plot in a randomized complete block design, replicated four times. A cropping system with sole maize, sole soybean and maize/soybean intercrop formed the main plot treatments while P rates with 0, 15 and 30 kg P₂O₅ ha^?1 were the subplot treatments. For both years, neither P fertilizer application nor cropping systems had a significant effect on maize grain yield. However, soybean grain yield was significantly higher (92.3% in 2007 and 44.5% in 2008) under sole cropping than under maize/soybean intercropping. On average, N fixed by soybean increased with the increase in P rate (from 51.8% without P to 60.5% with 30 P), but there was no significant difference in N fixed by sole soybean and soybean/maize intercrop. However, the interaction effect on N fixed between cropping systems and P rates was significant (P ≤ 0.05). N, P and K contents in maize grain were significantly higher (>100%) in intercropped maize than in sole maize. The cropping systems had no significant effect on post-harvest soil chemical characteristics. The land equivalent ratio was 1.52 in 2007 and 1.78 in 2008. The result shows that in utilizing legumes for N enrichment, the alleviation of P deficiency can enhance N₂-fixation by legumes. Furthermore, P replenishment in a maize/soybean intercrop may improve maize grain quality even though yield is not increased.     

Forms of fertilizer nitrogen residues in soil after intercropping of maize-cowpea

Summary Under greenhouse and field conditions, after the harvest of maize-cowpea intercropping, soils were analysed for total, ammonium and organic N fractions and fertilizer ¹⁵N residues. Growing cowpea as the sole crop or in intercropping with maize results in increased relative amounts of the acid hydrolysable organic N fractions in soil. After sole cropping of maize 70% of the residual fertilizer N was found in the acid hydrolysable fraction while after intercropping it was 80%–92%. The fertilizer and soil N labelling with ¹⁵N in identical but alternate series provided information on the nitrogen fixed by cowpea and left in the soil as crop residues. Under field conditions the cowpea plant residues left after cropping contained 170 kg N ha^–1 in sole cropping and 105 kg N ha^–1 in intercropping with maize. The N assimilated by cowpea-Rhizobium symbiosis was mainly present in the acid hydrolysable forms, particularly in the -amino N fraction and ammonium N fraction.     

甜玉米/白三叶草秸秆还田的碳氮矿化研究

豆科/禾本科作物间套作后进行秸秆还田能补充土壤养分,缓解集约化农业生产对环境的压力.根据田间甜玉米/白三叶草套种各作物的秸秆产量,在恒温恒湿条件下进行室内培养,探讨秸秆不同方式还田后土壤微生物量碳、微生物量氮、呼吸产生的CO2和矿化产生的无机氮的变化规律.研究发现,各施肥处理的土壤微生物量碳、微生物量氮均在培养前期出现峰值,后期平稳降低;甜玉米秸秆和白三叶草绿肥同时还田的土壤微生物量碳、微生物量氮在各培养时期均最大,峰值分别达529.57 mg·kg-1和75.50 mg·kg-1,土壤呼吸产生的CO2最多;白三叶草绿肥单独还田有利于土壤无机氮的释放,培养第26 d 无机氮达到最大值,为29.81 mg·kg-1,之后一直在对照处理的1.60倍以上,第80 d达到2.48倍;甜玉米秸秆单独还田不利于土壤无机氮的释放,培养的第26 d至结束,甜玉米秸秆处理的无机氮为对照的13%～53%,最大为7.51 mg·kg-1;甜玉米秸秆配施尿素,短期内不利于土壤无机氮矿化.结果表明,施用有机物料能引起土壤有机质的短期快速转化,甜玉米秸秆和白三叶草绿肥配施有利于维持较大基数的土壤微生物量,单施白三叶草绿肥土壤微生物活性强,最有利于土壤速效氮的释放.     

我国不同种类柑橘养分状况及氮磷钾推荐用量研究

  【目的】  调查不同种类柑橘果实矿质养分含量,结合土壤及树体养分含量状况,对我国主要种类柑橘进行推荐施肥研究。  【方法】  根据土壤类型 、 柑橘种类（ 宽皮柑橘类、甜橙类、柚类、柠檬类和杂柑类 ）、树龄及产量水平,将我国柑橘主产区湖北、湖南、江西、四川、广东、广西、福建、云南、浙 江、陕西、重庆等 11 省 (市、区) 的柑橘园划分为 1200 个采样单元,每个采样单元为3.3～6.7 hm2,于2010—2017年在柑橘成熟期 (9—12月),采集土壤、叶片及果实样品,调查柑橘产量、施肥量,分析叶片养分含量、土壤速效氮磷钾含量,并依据柑橘产量进行氮磷钾肥施用量及施用比例的推荐。  【结果】  低产水平果园氮 (N)、磷 (P₂O₅)、钾 (K₂O) 肥推荐用量:宽皮柑橘类分别为189.75～253.00、76.20～96.13、133.20～159.84 kg/hm2,甜橙类分别为176.94～235.92、101.02～123.47、128.03～153.64 kg/hm2;柚类分别为134.76～179.68、69.04～84.38、125.21～150.25 kg/hm2;柠檬类分别为91.33～121.77、55.43～67.75、79.68～95.62 kg/hm2;杂柑类分别为109.42～145.89、70.06～85.63、93.18～111.81 kg/hm2。中产水平果园氮 (N)、磷 (P₂O₅)、钾 (K₂O) 肥推荐用量:宽皮柑橘类分别为216.86～337.33、83.82～139.70、145.31～245.91 kg/hm2;甜橙类分别为202.22～314.56、111.12～185.20、139.67～236.37 kg/hm2;柚类分别为154.01～239.57、75.95～126.58、136.59～231.15 kg/hm2;柠檬类分别为104.37～162.36、60.98～101.63、86.92～147.10 kg/hm2;杂柑类分别为125.05～194.52、77.07～128.45、101.65～172.02 kg/hm2。高产水平果园氮 (N)、磷 (P₂O₅)、钾 (K₂O) 肥推荐用量:宽皮柑橘类分别为303.60～474.38、118.06～190.50、222.00～330.00 kg/hm2;甜橙类分别为283.10～442.35、156.51～252.55、213.39～320.08 kg/hm2;柚类分别为215.62～336.90、106.96～172.60、208.68～313.01 kg/hm2;柠檬类分别为146.12～243.54、85.88～147.82、132.80～212.48 kg/hm2;杂柑类分别为175.07～273.54、108.55～175.16、155.29～232.94 kg/hm2。  【结论】  5类柑橘对氮、磷、钾素需求量不同,其中宽皮柑橘类对氮、钾素需求较其它柑橘种类高,甜橙类对磷素需求量较其它柑橘种类高。5类柑橘对氮、磷、钾需求比例也有所不同,N∶P₂O₅∶K₂O需求比例分别为宽皮柑橘类1∶0.37～0.41∶0.63～0.73,甜橙类1∶0.52～0.59∶0.65～0.75,柚类1∶0.47～0.53∶0.84～0.97,柠檬类1∶0.56～0.63∶0.79～0.91,杂柑类1∶0.59～0.66∶0.77～0.89。     

减氮对华南地区甜玉米大豆间作系统产量稳定性的影响

在广东省广州市华南农业大学试验中心,通过大田定位试验（2013年秋-2017年秋5年9季）对比了两种施氮水平[减量施氮（300 kg·hm^-2,N1）和常规施氮（360 kg·hm^-2,N2）]、4种种植模式[甜玉米单作（SS）、甜玉米//大豆2：3间作（S2B3）、甜玉米//大豆2：4间作（S2B4）、大豆单作（SB）]的甜玉米、大豆及系统产量的动态变化,采用W²（Wricke''s ecovalence,生态价值指数）、变异系数（CV）和可持续指数（SYI）评价了产量的时间稳定性,旨在为华南地区一年2熟制甜玉米产区地力保育和绿色生产提供科学依据。结果表明：1）各处理甜玉米、大豆和系统总产量呈现明显的生产季节动态变化,不同年季、种植模式对甜玉米、大豆和系统总产量均有极显著影响,施氮水平仅显著影响甜玉米的产量。2）所有间作处理甜玉米的相对产量均高于单作,间作系统的实际产量损失指数（AYLs）均大于零,表明甜玉米//大豆间作能稳定地保持间作优势且显著提高了土地利用效率。3）不同处理甜玉米产量的W²、CV和SYI均没有显著差异,但单作大豆的W²值显著高于间作,单作大豆的产量稳定性低于间作大豆。种植模式对系统总产量稳定性有显著影响,且间作大豆提高了其稳定性。4）间作大豆显著提高了土壤地力贡献率,S2B3和S2B4的平均地力贡献率分别为75.07%和74.27%,比SS分别高30.29和29.47个百分点。5）与单作甜玉米相比,9季甜玉米//大豆间作显著提高了土壤pH,缓解了长期大量施氮导致的土壤酸化对地力的影响。连续减量施氮没有影响甜玉米//大豆间作系统土壤有机质和全量养分含量,300 kg·hm^-2的施氮量能够满足甜玉米和大豆对氮素的需要。减量施氮与间作大豆是华南甜玉米产区资源高效利用、系统产量稳定的可持续绿色生产模式。     

Performance of cowpea cultivars when grown as an intercrop with maize of contrasting maturities

A field trial was conducted during the rainy seasons of 2008 and 2009 at Samaru in northern Guinea savannah of Nigeria to determine the performance of semi-determinate and indeterminate cowpea cultivars intercropped with extra early, early and late maize cultivars. The trial was laid out in a randomized complete block design (RCBD) having treatments arranged as a split-plot factorial. Transmitted radiation was reduced by 49–63% due to shading by the maize plants. Similarly, intercropping cowpea with maize reduced intercepted radiation, fodder yield and grain yield of cowpea by 59–70%, 39–51% and 45–62%, respectively. Intercepted radiation and yields of intercropped cowpea were lower for late maize which maintained high leaf area over a longer period of time. This is supported by the higher plant height, higher leaf area index (LAI) and reduced transmitted radiation recorded in late maize compared with extra early and early maize. Extra early and early maize were less competitive with cowpea because of shorter period of association in addition to permitting higher radiation. Crop value of maize plus cowpea was higher than that of sole cowpea ($2616.8 vs. $1218.7 ha^?1) because higher combined yield was achieved by a more efficient use of resources in the intercrop. Therefore, cowpea cultivar may be intercropped with extra early maize.     

Preliminary evaluation of pineapple mixed-cropping systems for protecting reclaimed gulleys in the tropics: An experiment in Southeast Nigeria

This paper reports on research into the effectiveness of pineapple monocropping or intercropping systems (with cowpeas or egusi-melon) for reestablishing vegetative cover to check soil erosion on a reclaimed gulley in the tropical rainforest of southeastern Nigeria. High-density pineapple planting, intercropped with egusi-melon, was found to promote rapid vegetative cover, checked soil loss, improved soil structural stability and produced a high crop yield. Soil loss was moderate in pineapple plots intercropped with cowpeas and least in pineapple plots intercropped with egusi-melon. Increasing pineapple density enhanced the field establishment of cowpea and egusi-melon respectively.     

Cassava-legume intercrop: I. Effects of relative planting dates of legumes on cassava productivity

ABSTRACT

Cassava is a long duration crop which grows slowly during the early stages hence incorporation of early maturing crops may improve resource use efficiency and hence crop productivity in cassava-based cropping systems. We conducted field experiments in clay and loamy sand soils, in two consecutive seasons, to assess the response of cassava productivity to relative planting dates of 3 legume species (Bambara groundnut, chickpea and cowpea) in a cassava-legume intercrop. Root yield, determined at 10 months after planting, was greater at 4 weeks after cassava (1.7 kg plant^–1) compared to when legumes were planted same time (1.2 kg plant^–1) and 2 weeks after cassava (0.7 kg plant^–1), and intercropping decreased cassava root yield by 40% (cowpea) and 26% (chickpea) in season I in the clay soils. Neither relative planting dates of legumes nor cropping systems affected root yield in both seasons in the loamy sand soils. Intercropping increased LER in season I by 25% to 65% in clay, and 45% to 101% in loamy sand soils. Although cassava root yield was highest with a 4 week-delay in sowing the legumes and LER greatest in cassava-cowpea intercrop, we propose further studies before making any definite recommendations.     

5年间作和施氮对甜玉米和大豆产量、农艺性状的影响

为探讨种植模式和施氮水平对甜玉米（Zea mays L. var. Rugosa Bonaf.）和大豆[Glycine max(L.)Merr.]产量和农艺性状的影响,于2017—2021年连续5年在江西农业大学农业科技园开展大田定位试验,设置3个施氮量（N0,0 kg·hm-2;N1,150 kg·hm-2;N2,300 kg·hm-2）和3种种植模式（MC,甜玉米单作;MS,大豆单作;CS,甜玉米间作大豆）,分别在甜玉米和大豆的成熟期测定产量和农艺性状。结果表明,5年施氮（N1和N2）都显著增加了甜玉米鲜穗产量,但N1和N2处理间5年都无显著差异。相同施氮下间作较单作模式下的甜玉米鲜穗产量5年都无显著差异。随着种植年份的增加,不施氮的间作模式下甜玉米鲜穗产量在2020和2021年较2017年显著降低。甜玉米间作大豆模式中,甜玉米施氮（N1和N2）对大豆鲜荚产量5年都无显著影响。施氮显著增加了甜玉米株高、茎粗和穗位高。相对N2,N1仅在2017和2020年分别显著降低了单作甜玉米的茎粗和间作甜玉米的穗位高。5年数据相关性分析表明,间作模式下的甜玉米鲜穗产量与株高相关性更强,单作模式下...     

Comparison of broiler litter and inorganic nitrogen,phosphorus, and potassium for double‐cropped sweet corn and broccoli

Two rates of broiler litter (20 and 40 mt/ha) were compared to recommended rates of inorganic nitrogen (N), phosphorus (P), and potassium (K) in a double cropping system of spring sweet corn (Zea mays L. ‘Silverqueen') and fall broccoli (Brassica oleracea L, ‘Southern Comet')‐ Sweet corn matured one week earlier both years when fertilized with 40 mt/ha of broiler litter compared to commercial fertilizer. The early maturity may be due to improved P nutrition. Similar or higher yields of fall broccoli were produced with broiler litter following sweet corn than with commercial fertilizer.     

Mineral N dynamics in bare and cropped Leucaena leucocephala and Dactyladenia barteri alley cropping systems after the addition of 15N-labelled leaf residues

In tropical cropping systems with few external inputs, efficient management of mineral N derived from added organic residues is essential for the proper functioning of the system. We studied the dynamics of mineral nitrogen (N) in the top 100 cm of soil with a system of tensiometers and suction cups after applying ¹⁵N-labelled Leucaena leucocephala and Dactyladenia barteri residues to bare and cropped microplots installed in the respective alley cropping systems, and followed the fate of the N for two maize-cowpea rotations (1992 and 1993). Fifty days after applying the residues (DDA), 20% of the added residue N was found in the soil profile of the bare Leucaena treatment, and 5% under Dactyladenia, compared with 5% and 1%, respectively, where cropped. All values decreased to about 1% after 505 days. In the cropped soil, no mineral N derived from the residues was lost by leaching during the first 6 weeks. As the maize grew, the soil profile was gradually depleted of nitrate to near Zero in the Dactyladenia treatment, whereas during the cowpea season the amount of nitrate N increased to 36 kg N ha^?1 for the Leucaena treatment, and 26 kg N ha^?1 for the Dactyladenia treatment. The soil of the bare microplots contained substantially more nitrate N (98 and 47 kg N ha^-1 during the first year on average, under Leucaena and Dactyladenia, respetively) than that of the cropped microplots, except during the 1993 cowpea season. Nitrate residing in the subsoil (80–100 cm) in the bare treatments was not readily leached to deeper soil. The risk of losses of native mineral N was greatest during the first 50 DAA and to a lesser extent during the cowpea seasons. Improved management of the hedgerows could increase the potential of the hedgerow trees to recycle mineral N.     

Influence of an Arbuscular Mycorrhizal Fungus on Competition for Phosphorus Between Sweet Orange and a Leguminous Herb

Grass or herb intercropping with trees is widely practiced as an orchard-floor management strategy, but nutrient competition from grass species can inhibit the growth of intercropped fruit trees. Two experiments were conducted to investigate whether inoculation with the arbuscular mycorrhizal (AM) fungus Glomus versiforme can alleviate such competition and thus promote the growth of intercropped fruit trees by increasing soil nutrient exploitation. In the first experiment, intercropping was established in rhizoboxes containing sweet orange (Citrus sinensis) and the leguminous herb Stylosanthes gracilis inoculated with the AM fungus. Mycorrhizal inoculation did not appear to decrease competition, but increased the biomass of the herb much more than that of sweet orange. Inoculation had little effect on phosphorus (P) content of sweet orange, but significantly increased that of the legume roots. The AM fungal contribution to P uptake of the herb was twice that of sweet orange. Lateral roots of the herb tended to branch horizontally, with a large proportion entering the soil volume occupied by sweet orange; AM inoculation enhanced this effect. In Experiment 2, growth of the plants in monoculture revealed that the mycorrhizal dependency of the legume was much higher than that of sweet orange. It is suggested that mycorrhizal dependency can have a large influence on the role of the AM fungus in mediating competition in an intercropping system, and that fruit trees with high mycorrhizal dependency, together with a grass or herb with low mycorrhizal dependency, may be the optimum intercrop combination in orchards.     

Soil loss and run‐off characteristics under different soil amendments and cropping systems in the semi‐deciduous forest zone of Ghana

Soil erosion is a major constraint to crop production on smallholder arable lands in Sub‐Saharan Africa (SSA). Although different agronomic and mechanical measures have been proposed to minimize soil loss in the region and elsewhere, soil management practices involving biochar‐inorganic inputs interactions under common cropping systems within the framework of climate‐smart agriculture, have been little studied. This study aimed to assess the effect of different soil and crop management practices on soil loss characteristics under selected cropping systems, typical of the sub‐region. A two‐factor field experiment was conducted on run‐off plots under different soil amendments over three consecutive cropping seasons in the semi‐deciduous forest zone of Ghana. The treatments, consisting of three soil amendments (inorganic fertilizer, biochar, inorganic fertilizer + biochar and control) and four cropping systems (maize, soyabean, cowpea, maize intercropped with soyabean) constituted the sub‐plot and main plot factors, respectively. A bare plot was included as a soil erosion check. Seasonal soil loss was greater on the bare plots, which ranged from 9.75–14.5 Mg ha^?1. For individual crops grown alone, soil loss was 31%–40% less under cowpea than under maize. The soil management options, in addition to their direct role in plant nutrition, contributed to significant (p < 0.05) reductions in soil loss. The least soil loss (1.23–2.66 Mg ha^?1) was observed under NPK fertilizer + biochar treatment (NPK + BC) over the three consecutive cropping seasons. Biochar in combination with NPK fertilizer improved soil moisture content under cowpea crops and produced considerably smaller bulk density values than most other treatments. The NPK + BC consistently outperformed the separate mineral fertilizer and biochar treatments in biomass yield under all cropping systems. Biochar associated with inorganic fertilizers gave economic returns with value–cost ratio (VCR) > 2 under soyabean cropping system but had VCR < 2 under all other cropping systems. The study showed that biochar/NPK interactions could be exploited in minimizing soil loss from arable lands in SSA.     

Effects of cover crops on soil structure and on yield of subsequent arable crops grown under strip tillage on an eroded alfisol

Effects of weed fallow and of three grasses and five leguminous cover crops were investigated on soil structure of an eroded Alfisol. Crop growth and yields of subsequently grown arable crops were assessed under strip-tillage through the mechanically or chemically suppressed sods. Cover crops and fallowing improved soil organic matter content, total N, water retention and transmission properties, and decreased bulk density only in the top 0–10 cm depth. The improvements rendered were, however, slight. Grasses were difficult to suppress with paraquat or mechanical mowing, which resulted in low or negligible yield of maize, cowpea, and cassava. Leguminous covers were easily suppressed with paraquat application, and resulted in good yield of maize and cowpea. Mechanical mowing was as successful as herbicide application for suppressing Stylosanthes guianensis and resulted in satisfactory yield of maize and cowpea. Yield of cassava tubers was extremely low due to shallow surface soil, compacted sub-soil horizons, and competition from weeds and regrown cover crops. Results are discussed in terms of the amelioration of eroded and degraded soil.     

河西绿洲灌区间作绿肥及其不同利用方式对玉米产量及土壤肥力的提升效应

[目的]研究玉米间作不同绿肥及绿肥不同利用方式在河西绿洲灌区的生产效益.[方法]田间定位试验始于2009年,该试验为河西绿洲灌区的典型种植模式,至取样时试验已进行12年.与玉米间作的绿肥作物包括针叶豌豆、甜豌豆、草木樨,每种绿肥均采用压青与根茬还田两种方式,以玉米单作为对照(CK).测定了玉米和绿肥生物量、产量构成因素...