Mulched Plots Research Articles

Response of bacterial compositions to soil biochemical properties under mulching-intensive management in a Phyllostachys edulis forest

Phyllostachys edulis (Moso bamboo) is of great significance to forestry in China. Increased attention has been paid to exploring the role of underground ecology, especially soil microorganisms, in the cultivation and ecology of Moso bamboo. Mulching-intensive management can benefit Moso bamboo forests with low yields. However, the response of soil bacteria to changes in soil biochemical properties after intensive mulching is still unclear. In this study, the responses of the soil bacterial composition to changes in soil biochemical properties under different management conditions were analysed by sampling a bamboo forest under four management conditions: control, mulching, alternation and long-term mulching. The results showed that mulching and alternation could improve the diversity of soil bacteria at the phyla and genera levels, while long-term mulching had the opposite result. The relative abundances of Proteobacteria, Actinomycetes, TM7 and Bacteroides were lower in the control plots than in the other plots, while those of AD3, Verruca and GAL15 were higher. The results also showed that C (carbon), N (nitrogen) and P (phosphorus) accumulated rapidly in the mulching, alternation and long-term mulching plots due to the extensive application of organic and compound fertilizer. Soil acidification became obvious with the extension of mulching time. An increase in the C/N led to a decrease in substrate soil quality. Large amounts of total phosphorus (TP) and NO3−-N accumulated under long-term mulching, while the amounts of available phosphorus (AP) and NH4+-N decreased. The change in the microbial biomass carbon (MBC) content was consistent with that in the MBC/microbial biomass nitrogen (MBN), which decreased significantly in both the mulching plots and the long-term mulching plots, and alternation ameliorated the trend. MBC/MBN and pH were positively correlated with the bacterial composition at the genus level, while TP, NO3−-N, soil organic carbon (SOC) and water-soluble organic carbon (WSOC) were negatively correlated. The results showed that the soil bacteria did not benefit from the availability of relatively low-quality (high C/N) substrates, which was reflected by an imbalance in the soil bacteria composition under long-term mulching. Therefore, mulching is beneficial to the improvement of soil biochemical properties and the development of bacterial communities in a short period, but long-term mulching results in a significant decline compared with the other three management conditions. The soil biochemical environment and bacterial composition of Moso bamboo forest can be properly elevated by alternation, which is a necessary supplement to mulching and long-term mulching.

Quantification of soil water balance components based on continuous soil moisture measurement and the Richards equation in an irrigated agricultural field of a desert oasis

Abstract. An accurate assessment of soil water balance components (SWBCs) is necessary for improving irrigation strategies in any water-limited environment. However, quantitative information on SWBCs is usually challenging to obtain, because none of the components (i.e., irrigation, drainage, and evapotranspiration) can be easily measured under actual conditions. Soil moisture is a variable that integrates the water balance components of land surface hydrology, and the evolution of soil moisture is assumed to contain the memory of antecedent hydrologic fluxes, and can thus be used to determine SWBCs from a hydrologic balance. A database of soil moisture measurements from six experimental plots with different treatments in the middle Heihe River basin of China was used to test the potential of a such a database for estimating SWBCs. We first compared the hydrophysical properties of the soils in these plots, such as vertical saturated hydraulic conductivity (Ks) and soil water retention features, for supporting SWBC estimations. We then determined evapotranspiration and other SWBCs using a method that combined the soil water balance method and the inverse Richards equation (a model of unsaturated soil water flow based on the Richards equation). To test the accuracy of our estimation, we used both indirect methods (such as power consumption of the pumping irrigation well and published SWBCs values at nearby sites) and the water balance equation technique to verify the estimated SWBCs values, all of which showed good reliability with respect to our estimation method. Finally, the uncertainties of the proposed methods were analyzed to evaluate the systematic error of the SWBC estimation and any restrictions regarding its application. The results showed significant variances among the film-mulched plots in both the cumulative irrigation volumes (652.1–867.3 mm) and deep drainages (170.7–364.7 mm). Moreover, the un-mulched plot had remarkably higher values in both cumulative irrigation volumes (1186.5 mm) and deep drainages (651.8 mm) compared with the mulched plots. Obvious correlation existed between the volume of irrigation and that of drained water. However, the ET demands for all of the plots behaved pretty much the same, with the cumulative ET values ranging between 489.1 and 561.9 mm for the different treatments in 2016, suggesting that the superfluous irrigation amounts had limited influence on the accumulated ET throughout the growing season due to the poor water-holding capacity of the sandy soil. This work confirmed that relatively reasonable estimations of the SWBCs in coarse-textured sandy soils can be derived by using soil moisture measurements; the proposed methods provided a reliable solution over the entire growing season and showed a great potential for identifying appropriate irrigation amounts and frequencies, and thus a move toward sustainable water resources management, even under traditional surface irrigation conditions.

Abrasive Grit Application in Organic Red Pepper: An Opportunity for Integrating Nitrogen and Weed Management

Weeds are a top management concern among organic vegetable growers. Abrasive weeding is a nonchemical tactic using air-propelled abrasive grit to destroy weed seedlings within crop rows. Many grit types are effective, but if organic fertilizers are used, this could integrate weed and nutrient management in a single field pass. Our objective was to quantify the effects of abrasive grit and mulch type on weed suppression, disease severity, soil nitrogen availability, and yield of pepper (Capsicum annuum L. ‘Carmen’). A 2-year experiment was conducted in organic red sweet pepper at Urbana, IL, with four replicates of five abrasive grit treatments (walnut shell grits, soybean meal fertilizer, composted turkey litter fertilizer, a weedy control, and a weed-free control) and four mulch treatments (straw mulch, bioplastic film, polyethylene plastic film, and a bare soil control). Abrasive weeding, regardless of grit type, paired with bioplastic or polyethylene plastic mulch reduced in-row weed density (67 and 87%, respectively) and biomass (81 and 84%); however there was no significant benefit when paired with straw mulch or bare ground. Despite the addition of 6 to 34 kg N/ha/yr through the application of soybean meal and composted turkey litter grits, simulated plant N uptake was most influenced by mulch composition (e.g., plastic vs. straw) and weed abundance. Nitrogen immobilization in straw mulch plots reduced leaf greenness, plant height, and yield. Bacterial spot (Xanthomonas campestris pv. Vesicatoria) was confirmed on peppers in both years, but abrasive weeding did not increase severity of the disease. Pepper yield was always greatest in the weed-free control and lowest in straw mulch and bare soil, but the combination of abrasive weeding (regardless of grit type) and bioplastic or polyethylene plastic mulch increased marketable yield by 47% and 21%, respectively, compared with the weedy control. Overall, results demonstrate that when abrasive weeding is paired with bioplastic or polyethylene mulch, growers can concurrently suppress weeds and increase crop N uptake for greater yields.

Reduced herbicide rates for control of living mulch and weeds in fresh market tomato

AbstractLiving mulches can provide many sustainability benefits. However, living mulch–cash crop competition and unreliable weed control are major challenges in living mulch systems. In this study, we evaluated the potential of herbicides used at reduced rates in combination with living mulch to suppress weeds, while simultaneously reducing living mulch vigor. Herbicide treatments were a combination of two POST applications, each consisting of a single, different herbicide. Field trials were conducted in Freeville, NY, USA, using: fresh market field tomato as cash crop; sesbania and sunn hemp as living mulch; and the herbicides fomesafen, halosulfuron, metribuzin, and rimsulfuron. In 2015, when water was not limiting, tomato yield and living mulch biomass were positively correlated. This relationship was negative in 2016, likely because of drought during the growing season. Compared with the untreated living mulch check, using the herbicide treatments in combination with living mulch reduced tomato yield losses by up to 71% in 2015 and 51% in 2016. In these herbicide plus living mulch plots, weed biomass was reduced by up to 97%, compared with the weedy check. Living mulch in herbicide treatments generated up to 2500 kg ha−1 of dry matter during both 2015 and 2016, with an average ground cover of 63% in 2015 and 85% in 2016. A predominantly PRE herbicide with residual soil activity (metribuzin), followed by a herbicide with greater POST activity (halosulfuron/rimsulfuron) was the most effective herbicide application sequence. Results from our study indicate that well-designed herbicide applications may enhance the practicability of living mulch systems.

Does helimulching after severe wildfire affect vegetation recovery in a coastal area of Northwest Spain?

Helimulching is commonly applied after high-severity wildfires in North America because of its effectiveness in reducing post-fire runoff and erosion. However, its use in other parts of the world is still very limited and information about its effects in different environments is scarce. In this study, the effects of helimulching on vegetation recovery and species composition were assessed in 70 experimental plots (80 m2 each) established in five shrubland areas in Northwest Spain affected by wildfire in summer 2013. The effects on shrub, forb, fern and grass cover, and on total vegetation cover, as well as on species richness, Shannon diversity index and heterogeneity were studied over the 2 years following the fire. The impacts of soil burn severity and mulch depth on these variables were also considered. Overall, the mulching treatment had little effect on the cover variables. Although it had a positive effect on forb cover, these species represented only a small portion of the total vegetation cover. Soil burn severity was not a significant factor in explaining the variation in the variables under study. The treatment had a low impact on species composition. In the mulched plots only three non-native species were recorded and these displayed a limited capacity to act as invasive species as they were absent at the end of the period of study. The results indicate that helimulching is a feasible soil stabilization treatment with neutral effects on vegetation cover and the composition of shrubland in coastal areas of Northwest Spain.

Long-term vegetation response following post-fire straw mulching

BackgroundStraw mulching is one of the most common treatments applied immediately post fire to reduce soil erosion potential and mitigate post-fire effects on water quality, downstream property, and infrastructure, but little is known about the long-term effects on vegetation response. We sampled six fires that were mulched between 9 and 13 years ago in western US dry conifer forests. We compared understory plant species diversity and abundance, tree seedling density and height by species, and fractional ground cover on mulched and unmulched paired plots.ResultsMulch did not influence understory plant diversity, species richness, or fractional ground cover. However, on mulched plots, tree seedlings grew taller faster, especially on north-facing aspects, and there was slightly more graminoid cover. Mulch did not affect overall tree seedling density, but there were fewer ponderosa pine (Pinus ponderosa Lawson & C. Lawson) and more Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) in mulched areas, especially on south-facing slopes.ConclusionsManagers will be able to weigh the long-term implications of mulching against the short-term reductions in soil erosion potential. While there are many concerns about vegetation suppression and exotic species introduction from using straw mulch, our study suggests that the long-term effects are subtle 9 to 13 years after post-fire mulching.

Hydrologic and erosion responses to compaction and added surface cover in post-fire logged areas: Isolating splash, interrill and rill erosion

Soil compaction during post-fire logging can increase runoff and erosion. Increasing surface cover is an effective way to reduce erosion, but this has not been tested on soils impacted by both fire and compaction. We measured the effects of compaction (bulk density of 0.9 or 1.1 g cm−3) and surface cover (0% or 60%) using bark mulch or logging slash (compacted only) on runoff, leaching and erosion. Four 0.5 m2 plots per treatment were filled with burned soil and inclined to 18°. Two 30-min simulated rainfall events with 72 mm h−1 intensity and one concentrated flow event were applied to each plot.The runoff from the dry and wet runs totaled 32 mm in the uncompacted bare plots and the value was not significantly different for the compacted bare plots, any of the mulch plots, or the compacted slash plots. Leaching was higher for the uncompacted bare plots (7 mm) than for the compacted bare plots (1 mm), and mulch or slash did not affect leaching. The uncompacted bare plots produced 38 g of rainsplash and 497 g m−2 of sheetwash, and these were about half the values for the compacted bare plots. Mulching strongly reduced the rainsplash and sheetwash for both the uncompacted (10 g and 184 g m−2, respectively) and compacted conditions (19 g and 431 g m−2, respectively), although the difference in sheetwash was only significant for the uncompacted plots. Slash also reduced rainsplash (19 g) relative to the compacted bare plots (74 g) but did not affect sheetwash. Concentrated flow produced 858 g m−2 of rilling from the uncompacted bare plots, which was greater than the compacted plots (237 g m−2). Mulching reduced rilling by 95% in the uncompacted plots and 78% in the compacted plots, but slash did not reduce rilling.The reductions in rainsplash erosion caused by the mulch and slash were attributed to the increase in surface cover, which reduced the energy imparted to the soil by the rainfall. The mulch, with its high degree of contact with the soil, also reduced particle detachment and transport by overland flow. In contrast, the slash did not have complete contact with the soil surface and did not affect sheetwash or rilling. Compaction and the type of material used to increase surface cover are important factors to consider when assessing potential impacts of logging on runoff and sediment delivery from burned soils.

Management of potato leaf miner in Uganda

The yield of potato, an important food security and income crop in Uganda is substantially affected by pests. A survey was carried out in south western Uganda, a major potato growing area to assess the distribution and severity of potato pests in June and July 2015. In addition, leaf miner management options such as pesticide use, yellow sticky traps and mulching were evaluated for effectiveness. Trials in leaf miner hot spots in Bukimbiri and Chahi sub-counties of Kisoro district were conducted in three seasons during 2016 to 2017. In each sub-county, two sites were selected per season and trials were established in a completely randomized design with each treatment being replicated three times. From the survey, aphids and leaf miners were the major pests with high incidences in Kabale and Kisoro districts and rarely encountered in Rukungiri and Kanungu. Use of Dudu-acelamectin reduced leaf miner damage on leaves in season 1 (2017; P=0.001) and registered significantly higher yields compared to other treatments. Yellow sticky traps trapped high leaf miner fly populations but leaf miner damage on leaves and yield were not significantly different from control and mulched plots. Judicious use of pesticides in high leaf miner populations together with yellow sticky traps can reduce leaf miner populations and damage on potato. Key words: Potato, potato leaf miner, pesticides, yellow sticky traps.

Effects of Organic Weed Control Methods on Weed Density, Phenotypic Traits and Yield Attribute of Cucumber (Cucumis Sativus)

Organic weed control methods has a long time record in conserving soil moisture, improving soil structure and increasing soil organic matter. This testimonial should not be left out to manifest on vegetable crops that serve greater part as supplement for balanced meals. Field experiment was conducted in two years (2016 and 2017) to investigate the effects of different organic weed control methods on weed density, phenotypic traits and yield of Cucumber. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. The experimental site was marked into (4) blocks while each block was also marked into (3) plots, giving a total number of (12) plots. Plots were 4m x 4m. Two seeds were planted per hole with inter and intra row spacing of 1m x 1m.The results showed that mulched plots (Sawdust and wood shaving) and hoe weeding had higher and significant growth and harvested number of fruits per plant (yield), compared to the control (Weedy and non-mulched plots), this indicated that mulching and hoe weeding as methods of organic weed control have positive effects on reducing weed emergence, increase growth and yield of cucumber. It was concluded that higher yield is not only synonymous to use of synthetic chemicals (pesticides and herbicides) but as well to cost effective and safe organic management practices in breeding programmes. Keywords: Organic, weed control, weed density, phenotypic traits and yield attributes. DOI : 10.7176/JBAH/9-10-12 Publication date :May 31 st 2019

Effect of mulch and organic amendment on yield performance of dry direct seeded BORO rice

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during the period from February to June 2018 with a view to study the effect of mulch and organic amendments on growth and yield performance of BRRI dhan58 under dry direct seeded boro rice production system. The experiment included two set of treatments. A. Mulch (M1=rice straw mulch @ 7 t ha-1 and M2=No mulch) and B. Organic amendments (T1=Trico-compost (TC) @ 5 t ha-1, T2 =Farm Yard Manure (FYM) @ 5 t ha-1, T3 =Mustard Oil Cake (MOC) @ 0.5 t ha-1, T4= Trico-compost (TC) @ 5 t ha-1 + Mustard Oil Cake (MOC) @ 0.5 t ha-1, T5 = Farm Yard Manure (FYM) @ 5 t ha-1 + Mustard Oil Cake (MOC) @ 0.5 t ha-1, T6=Control). The experiment was laid out in a split-plot design with mulch in the main plot and organic amendments in the sub-plot. The treatments were replicated three times. The higher plant height (95.90 cm), no. of effective tillers hill-1 (11.48), 1000-grains weight (24.75 g), grain yield (5.34 t ha-1), and straw yield (7.38 t ha1) were found from rice straw mulch plots. The highest plant height (103.40 cm), panicle length (23.24 cm), no. of grain panicle-1 (118.79), 1000-grain weight (25.23 g), grain yield (5.67 t ha-1), straw yield (7.80 t ha-1), biological yield (13.47 t ha-1) and harvest index (42.06%) were found from treatment T4 (Tricho compost+Muatard Oil Cake). The crop grown with recommended rate of fertilizers (T6) gave the worst performance. The interaction between mulch and organic amendments were not significant for grain yield. Thus the study concludes that rice straw mulching gives better yield than no mulch plots and the organic amendment is better than recommended inorganic fertilizer application.
 Asian Australas. J. Biosci. Biotechnol. 2019, 4 (1), 48-59

Kuru Üretim Zeytin Bahçelerinde Yağmur Suyu Hasadı Malç Uygulamasıyla Toprak ve Su Muhafazasının İncelenmesi

Su hasadı teknikleri kurak alanlarda yağmur sularını biriktirerek su sıkıntısının ve kuraklığın etkilerini azaltmanın yanı sıra, toprak ve su koruma açısından da yarar sağlamaktadır. Bu çalışmada, yağışların yetersiz olduğu yarı kurak iklime sahip Güneydoğu Anadolu bölgesinde, sulama olanağı bulunmayan genellikle eğimli arazilere tesis edilmiş zeytin bahçelerinde toprak ve su erozyonu kontrolünü sağlamak amacıyla, Negarim mikro havza yağmur suyu hasadı tekniği uygulanmıştır. Bu çalışmada; yağmur suyunun bitkinin kök bölgesinde birikimini sağlamak amacıyla Negarim adı verilen mikro havzalar içerisine yerleştirilen plastik örtü, taş örtü, mikro-havza yüzeyinin sıkıştırılması ve kontrol konularından oluşan 36 adet mikro-havzanın toprak ve su erozyonuna olan etkisi değerlendirilmiştir. Araştırmada 2009-2010 yılları boyunca yüzey akış ve sediment kayıpları ile bitki gelişimi ölçülmüştür. Araştırma sonuçlarına göre yıllık ortalama yağışı 250 ile 400 mm arasında değişen deneme alanında, 2 su yılı boyunca meydana gelen ortalama maksimum yüzey akış 6201 L/parsel ile plastik örtü konusunda, ortalama minimum yüzey akış 810 L/parsel ile taş örtü konusunda belirlenmiştir. Ortalama maksimum sediment kaybı 1163 g/parsel ile yüzey sıkıştırma konusunda, ortalama minimum sediment kaybı ise 673,5 g/parsel ile taş örtü konusunda ölçülmüştür. Mikro-havza yüzeyi plastik örtü ile kaplı olduğundan erozyon kontrolünü en iyi şekilde sağlayan uygulama plastik örtü olarak saptanmıştır. Plastik örtü konusu en iyi yüzey akışı gerçekleştirdiğinden bitki boyu gelişimi yönünden ortalama 107,5cm uzunluk ile en iyi uygulama olmuştur. Sonuç olarak kuru koşullarda ve eğimli arazilerde üretimi yapılan zeytin bahçelerinde Negarim mikro havza su hasadı tekniğinin ağaçların büyüme ve gelişimi arttırmanın yanı sıra toprak ve su muhafazası açısından da yararlı ve uygulanabilir bir teknik olduğu sonucuna ulaşılmıştır.

Plastic film mulching increased the accumulation and human health risks of phthalate esters in wheat grains

Plastic film mulching is a common practice to increase crop yield in dryland, while the wide use of plastic film has resulted in ubiquitous phthalate esters (PAEs) releasing into the soil. PAEs in soil could be taken up and accumulated by dietary intake of food crops such as wheat, thus imposing health risks to residents. In the present study, samples from a long-term location-fixed field experiment were examined to clarify the accumulation of PAEs in soil and wheat, and to assess the human health risks from PAEs via dietary intake of wheat grain under plastic film mulching cultivation in dryland. Results showed that concentrations of PAEs in grains from mulching plots ranged from 4.1 to 12.6 mg kg−1, which were significantly higher than those in the control group. There was a positive correlation for the PAE concentrations between wheat grains and field soils. Concentrations of PAEs in the soil were in the range of 1.8–3.5 mg kg−1 for the mulching treatment, and 0.9–2.7 mg kg−1 for the control group. Di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) were detected in all soil and grain samples, and DEHP was found to be the dominant PAE compound in grains. Based on DEHP concentrations in wheat grains, the values of carcinogenic risk for adults were higher than the recommended value 10−4. Results indicated that wheat grains from film mulching plots posed a considerable non-carcinogenic risk to residents, with children being the most sensitive resident group. Findings of this work call the attention to the potential pollution of grain crops growing in the plastic film mulching crop production systems.

Impact of no-till and mulching on soil carbon sequestration under rice (Oryza sativa L.)-rapeseed (Brassica campestris L. var. rapeseed) cropping system in hilly agro-ecosystem of the Eastern Himalayas, India

Decline in soil organic carbon (SOC) and low biomass production in sloping uplands are of growing concern for sustainable agriculture worldwide. This concern is in general in the Eastern Himalayan regions (EHR) of India in particular. A field experiment was conducted with the objectives to generate additional biomass and sequester more C in coarse-textured sloping lands. This experiment is done for four consecutive years in the EHR, India. The rice (Oryza sativa L.)–rapeseed (Brassica campestris L. var. rapeseed) cropping system was practiced during the first two years (2012-13 to 2013-14) and rice–rapeseed–cowpea (Vigna unguiculata L.) system during the two following years (2014-15 to 2015-16) of the study under different tillage and mulch systems. The tillage system included: 1) CT-RI: conventional tillage (CT) with 100% residue incorporation (RI) and 2) NT-RR: no-till (NT) with 100% residue retention (RR). The mulches included 1) rice straw mulch (SM), 2) Gliricidia sp. mulch (GM), 3) brown manuring mulch (BM)–cowpea grown as intercrop with rice up to 40 days after sowing (DAS), killed with 2,4-D and 4) no mulch (NM). The cowpea, as a cover crop was introduced during 2014 and 2015 as pre-rainy season crop before the sowing of rice to generate additional biomass in the system. The four year total above ground biomass yield of rice and rapeseed didn’t vary significantly between CT-RI (31.93 and 17.40 Mg ha−1) and NT-RR (31.86 and 17.46 Mg ha−1), respectively. However, the total above ground biomass yield of cowpea was more under NT-RR (10.75 Mg ha−1) when compared to that under CT-RI (9.79 Mg ha−1). The amount of total biomass (above + below ground) and C added into the soil was more under NT-RR than that under the CT-RI. After 4 cropping cycles, the NT-RR had higher SOC concentration, pool (29.9 vs. 29.1 Mg ha−1), sequestration rate (450 vs. 265 kg ha-1 yr−1) and C retention efficiency (7.7 vs. 4.6%) than those under the CT-RI at 0–30 cm depth. The mulched plots produced more crop biomass (both above and below ground), recycled more C in soils with a trend of relatively more SOC pool (29.7–29.8 vs. 29.0 Mg ha−1), sequestration rate (391–428 vs. 221 kg ha-1 yr−1) and C retention efficiency (6.64–6.94% vs. 4.66%) than those of NM treatment. These results were seen despite difference among the mulch treatments (SM, GM and BM) which were statistically non-significant after 4 cropping cycles. Inclusion of cowpea as cover crop during pre-rainy season in the system doubled the rate of C sequestration (478 kg C ha-1 yr−1). Therefore, the data supports the recommendation of cultivation of the rice–rapeseed system under NT-RR along with cowpea intercropping up to 40 DAS (BM) in rice. Besides this, the inclusion of pre-rainy season cowpea before rice could generate additional biomass and enhance SOC sequestration on upland and sloping hills in the EHR of India and in similar conditions elsewhere.

Integrated model and field experiment to determine the optimum planting density in plastic film mulched rainfed agriculture

Ridge–furrow mulching with plastic film is widespread in northern China because it can significantly improve crop yields. Whether maize grain yield would further increase with higher plant density, due to the better soil moisture conditions under plastic mulch, is unknown. A process-based model (DeNitrification–DeComposition) coupled with a field experiment during the 2014–2015 growing seasons was used to evaluate the effect of plant density on yield. The field experiment included three treatment groups: soil fully covered with transparent polyethylene film (PM) with plant densities 35,000 (PM35), 45,000 (PM45), and 65,000 plants ha–1 (PM65) and bare soil with a maize planting density of 45,000 plants ha–1 as the control (CK). The DNDC simulated yield in PM and CK was well-matched with the measured values and maize growth pattern, and explained 64% of the yield variation and had an RMSE of 176 kg ha–1. At the same planting density (45,000 plants ha–1), individual plant weight, grain weight per plant, 100-seed weight, and grain yield in the non-mulched plots were 45, 28, 52, and 28% of the values for mulched plots, respectively. In the mulched plots, the individual plant size, grain weight, and seed size significantly decreased as planting density increased. The PM65 had 8% and 19% higher grain yield than PM45 and PM35, respectively. Increasing planting density above 45,000 plant ha–1 in the PM resulted in a small but non-significant increase in grain yield. We concluded that increasing plant density in PM will not necessarily increase maize yield, and the optimum planting density could be determined by combining the field experiment with the model.

Nutrient concentrations in leachate and runoff from dairy cattle lots with different surface materials

Nitrogen (N) and phosphorus (P) loss from agriculture persists as a water quality issue, and outdoor cattle lots can have a high loss potential. We monitored nutrient concentrations in leachate and runoff from constructed dairy heifer lots. Lots were about 42 m², excavated to 1.1 m deep, and backfilled with three surface materials (soil, sand, and bark mulch). Plots were lined with a rubber membrane to allow total collection of all leachate. Runoff was collected from soil plots only. Runoff and leachate were monitored for dissolved and total N and P from 2010 to 2015. Dairy heifers were placed on plots several times per year for a week at a time. The percentage of annual precipitation collected as leachate averaged 34% for soil, 75% for sand, and 64% for mulch plots. For soil plots, the percentage of annual precipitation collected as runoff ranged from 13% to 44%, with the percentage increasing with precipitation. Leachate N concentrations in soil and sand plots behaved similarly, with ammonium-N (NH₄-N) much less than nitrate-N (NO₃-N) and total N. Leachate N concentrations were generally least from mulch, suggesting more microbial N retention. Soil had the least and sand plots had the greatest P concentrations in leachate, with mulch in between. In runoff from soil plots, particulate N and P were well related to sediment concentrations. Compared with leachate from soil and sand, soil runoff NO₃-N concentrations were typically less, but were similar to leachate in mulch plots. Conversely, soil runoff NH₄-N concentrations were typically greater than in leachate for any treatment. Soil runoff dissolved P concentrations increased slightly over time, with most runoff P when cows were recently on plots, and were typically greater than in leachate for any treatment. Overall, nutrient dynamics in sand and soil plots appeared controlled by mineral processes, while biological processes dominated more in mulch plots. Sand plots had the most nutrients in leachate, implying more potential to recover nutrients in liquid form. Soil and mulch retained more nutrients within plot materials, which means on-farm nutrient use would require transfer of materials to cropland or growing crops directly in previous cattle lots.

Nutrient Mass Balance and Fate in Dairy Cattle Lots with Different Surface Materials

Abstract.On dairy farms, outdoor lots where cows spend substantial time can be areas of high nutrient deposition in manure. This represents an inefficient use of farm nutrients, if the nutrients are not recovered, and a potential for nutrient loss to the environment. Management of barnyards to recover nutrients can have environmental and production benefits. We monitored nitrogen (N) and phosphorus (P) fate for five years in dairy heifer barnyard plots constructed with soil, sand, or bark mulch surfaces. The plots were stocked with heifers several times per year for about a week at a time. We monitored N and P loss in runoff (soil plots only), leachate, and gas emissions. Of the total N inputs to the plots through heifer excretion, 6% to 8% of inputs were lost in runoff (~2%), leachate (~3% to 4%), and gas emissions (~3% to 4%) from the soil and mulch plots. Most of the N inputs remained in the surface materials. For the sand plots, more N inputs were lost in leachate (~13%) and gas emissions (~6%), but most of the N remained in the surface material. Of total P inputs to the plots through heifer excretion, 4% to 6% of inputs were lost in runoff and leachate, with most of the P remaining in the surface materials. The results suggest that most of the nutrients deposited by heifers onto barnyards could be recovered and used as fertilizer for crop growth by excavating the surface materials and spreading them on cropland, by including animal holding areas in land used for crop rotation so crops can recover nutrients , or by corralling animals directly on cropland. Keywords: Barnyards, Cattle, Leaching, Nutrients, Runoff.

Influence of Different Planting Methods and Mulching on Growth and Yield of Spring Maize (Zea mays L)

The field experiment was conducted to study the effect of different planting methods and mulching on the growth and yield of spring maize (Zea mays L)on sandy loam soil, low in organic carbon and available N and high in available P and K. The experiment was carried out in split plot design with twelve treatment combinations having three planting methods viz., single row on bed (SR), double row on bed (DR) and paired row on bed (PR) in main plots and four live mulch treatments in sub plots including control, moong, mash and cowpea replicated four times. The results indicated that different planting methods and mulching had a significant effect on the growth and yield components of spring maize. The planting of maize with double row on bed gave significantly higher plant height, periodic leaf area index, dry matter accumulation, number of cobs per plant, number of grains per cob, straw yield and harvest index. Test weight was not influenced significantly. Grain yield (kg/ha) were also significantly more in double row on bed over paired row on bed but single row on bed was at par with it. Among the mulch plots mulching with cowpea recorded the highest growth and yield components. Test weight was not influenced significantly. Grain yield (kg/ha) was recorded maximum in cowpea mulch plots followed by moong, mash and least was in control plot.

Weed Control in Tomato (<i>Solanum lycopersicum</i>) Through Mulch Types in Kakamega County, Kenya

Tomato (Solanum lycopersicum) is the third most important vegetable crop after potato (Solanum tuberosum) and onion (Allium cepa). Its production heavily involves the use of synthetic pesticides with detrimental impact on humans, insect pollinators, water sources, soil fertility and environment. This study uses different mulch types to mitigate this problem. Mulching is an agricultural technique that protects the roots of plants from heat and cold by use of inorganic and organic mulch types to cover the soil surface around plants. Tomato production in Kakamega County is below 2%. Weeds are ranked high among the yield reducing factors. This study consists of four mulch treatments of white polyethylene (0.18mm thick), maize stalks (18.0cm thick), grass clippings (18.0cm thick), guava leaves (18.0cm thick) and no mulch as control with three popularly grown tomato varieties. The mulch treatments were arranged as factorial in a completely randomized block design replicated three times in the experimental plots, at Masinde Muliro University of Science and Technology (0°171N, 34°451E). Tomato variety sub-treatments were completely randomized in the plots to minimize non–experimental bias during sampling weeds incidence. The field project was conducted during the short rains and long rains season of 2016-2017. Data obtained was subjected to analysis of variance (ANOVA) using SAS software, version 9.3 (SAS Institute lnc.) at p<0.05 confidence level. Least Significance Difference (LSD) was used to separate the means. Mean weed density was significantly highest in control plots (94.51%) and least in mulched plots (11.41%). The tomato plant growth parameters (leaf length, leaf width, stem height and stem width) were significantly higher in mulched than control plots. Mulches provide clean field sanitation, inhibits weed seed germination, promotes plant growth with high crop yields and reduces synthetic pesticides and herbicides application.

Planting method, row arrangement and crop residue mulch influence on weed dynamics and productivity of toria mustard

A field study was conducted at ICAR-Research Complex for NEH Region, Basar during 2012–13 to study the effect of planting methods, row arrangement and mulching on toria (Brassica campestris L.) and associated weeds. Results revealed that at 30 and 60 days after sowing (DAS), the weed density and weed dry biomass were lesser in ridge and furrow; among row arrangement lower weeds at 6 rows followed by 3 rows over normal row planting. However, between the mulch, at 30 DAS the lower density and dry biomass were recorded with groundnut haulm mulching at 4 t/ha over no mulch, whereas at 60 DAS, dramatically no mulch plots had lesser weeds as compared to mulched plots. The number of branches/plant, siliqua/plant, seeds/siliqua, seed and stover yields were higher in ridge and furrow at 6 rows arrangement with groundnut haulm mulch at 4 t/ha.

Eco-biology and management of onion thrips (Thysanoptera: Thripidae)

Thrips tabaci is worldwide distributed polyphagous pest infesting approximately 140 plant species and is major pest of onion. T. tabaci transmitted IYSV and caused up to 100% damage. Numbers of generation is 2–9 per year depending on environment. Population dispersion depends on abiotic condition, planting date, variety and cropping pattern. Spreading of population was faster when temperature rises between 20.8 -27.7°C and decreased with rainfall, relative humidity and wind speed of 13.7 kph. The attack is more on older plant where outer and upper section of leaves receives 95% of eggs approximately. Host selection and preference is more on cultivars with narrow angles of leaves, dark and waxy coating leaves with high sugar content. Staggered planting of onion and balanced nutrients results in less colonization of onion thrips. Organic mulched plot promotes bioagents and thus low incidence was recorded. A total of 36 predators, 7 parasitoids and 12 fungal pathogens and numbers of botanical insecticides showed effective against onion thrips.