Direct and residual fertilizer values of maize (Zea mays L.) stover co-composted with Tithonia diversifolia (Hemsl.) A. Gray green manure

The present investigation highlights and compares the direct and residual fertilizer values of maize (Zea mays L.) stover composted with Calliandra calothyrsus Meisn and Tithonia diversifolia (Hemsl.) A. Gray-green manure on maize (Zea mays L.) and successive potato (Solanum tuberosum L.).  Two field studies were installed with maize and successive potato crops in a completely randomized block design (CRBD) with three replicates. Statistical analyses were performed using R commander, version 4.0.2. Grain yields, root biomass, above ground biomass and calculated parameters (Root/Shoot ratio, Harvest Index and GinningRate) were evaluated for maize. Total potato yields were evaluated and categorized into small size tubers (SST < 35 mm) medium size tubers (MST: 35-65 mm) and big size tubers (BST > 65 mm). Treatments under evaluation were: T1=Control, T2=Farm (cow) manure alone, T3=Maize stover co-composted with Calliandra calothyrsus Meisn green manure; T4= Maize stover co-composted with Tithonia diversifolia (Hemsl.) A. Gray green manure; T5= Farm (cow) manure+45-60-30; T6= Maize stover co-composted with Calliandra calothyrsus Meisn green manure+45-60-30; T7=Maize stover co-composted with Tithonia diversifolia (Hemsl.) A. Gray green manure+45-60-30; and T8=Farm (cow) manure+FOMI Imbura+FOMI Totahaza. Obtained results indicated highest maize yields with FOMI organo-mineral fertilizers (2.7 T/ha) seconded by the recommended fertilizer practice T5 (2 T/ha). In the same line, highest R/S value (=0.38) was registered with the same FOMI treatment (T8), while the highest HI value (0.21) was observed with the maize stover co-composted with Tithonia diversifolia (Hemsl.) A. Gray (T4). Highest potato total yields were observed with the maize stover compost enriched with Tithonia diversifolia (Hemsl.) A. Gray and supplemented with mineral fertilizer (7.61 T/ha), followed by the same compost without mineral fertilizer addition (6.35 T/ha). We conclude our study with the following statements: i) the highest direct fertilizer value was observed with the FOMI treatment; ii) the residual fertilizer effects were more expressed with the maize stover co-composted with Tithonia diversifolia A. Gray green manure with or without mineral additive, followed by farm manure and maize stover enriched with Calliandra calothyrsus Meisn green manure. Consequently, we restate that the effects of compost-based organo-mineral fertilizers on crop yields should be definitely evaluated on a multiseasonal basis so as to fully capture their residual fertilizer potentials

Comparative Analysis of Different Fertilizers Effects on Maize Growth Parameters

Lower soil fertility was identified as a major problem affecting crop yield in Burundi, especially at Bihunge, a hill of Matongo commune Kayanza province. An experiment was therefore carried out with five treatments to assess the effective and economically affordable treatment on maze growth parameters improvement. The experimental has considered five treatments: the control (T1); Compost from maize residues + mineral adjuvant (T2); Compost from maize residues + organic adjuvant based on Calliandra calothyrsus Meisn (T3); ISABU formula for maize fertilization (T4); the maize compost + Calliandra + recommended mineral fertilization for maize (T5)), in randomized complete blocks with three replications for each. The recorded parameters were the leaves number, plant height, stem girth as well as the leaf area. After analysis with SPSS and Advanced Excel, results showed a significant difference between treatments. The treatment T4 was the most effective in improving all growth parameters than others and showed a significant difference from treatments T1, T2, and T3. However, it did not differ to treatment T5 which also significantly differed from other treatments with P<0.05.  Treatment T5 has also effectively enhanced the leaves number, plant height, stem girth, and leaf area as treatment T4, and was in the same variation range as this treatment T4. As the effectiveness of T5 was based on the combination of calliandra which has more potential in improving soil fertility and nutrient followed by better fostering of nutrients to the plant leading to better-improved plant growth, this treatment was considered as the effective and farmer accessible treatment for maize cultivation

Occurrence and density of the stink bug Antestiopsis thunbergii Gmelin 1790 (Heteroptera: Pentatomidae) and related egg-parasitoids in Burundi coffee agroecosystems

International audienceAntestiopsis thunbergii is the most important coffee pest in Burundi causing yield losses of up to 30%. The aim of this study was to estimate its occurrence and density and to assess the species diversity of native egg-parasitoids associated to this pest in coffee agroecosystems. Our study was carried out in four coffee growing agro-ecological zones of Burundi namely; the humid west escarpments, the humid central highlands, the sub-humid central highlands and the sub-humid southeastern and northern depressions. In total, 600 coffee trees, randomly selected in 40 coffee plots of 20 communes were investigated at three phenological stages of the crop viz. October 2019 (coffee was flowering), January 2020 (coffee berries were immature green) and April 2020 (coffee berries were mature green and red). The results showed a permanent presence of A. thunbergii with an increasing occurrence and density with time. Densities were above the economic threshold (one antestia bug per tree), except in the humid west escarpments. Differences were highly significant among the four agro-ecological zones at each time of sampling. The humid central highlands zone registered the highest densities with 1.55, 1.31 and 2.67 antestia bugs per tree in October, January and April, respectively. The humid west escarpments zone recorded lower densities of 0.38, 0.44 and 0.88 antestia bugs per tree, for the same periods respectively. From the 4,776 eggs collected from the field, 1,99 egg-parasitoids of A. thunbergii were obtained and identified, namely Trissolcus sp. (59.2%), Telenomus seychellensis (29.6%), Gryon fulviventre (2.9%), Anastatus sp. (8.1%) and Acroclisoides africanus (0.2%)

Yield Responses of Maize (Zea mays L.) and Successive Potato (Solanum tuberosum L.) Crops to Maize Stover co-composted with Calliandra Calothyrsus Meisn Green Manure

The present investigation aimed at evaluating the effect of Calliandra calothyrsus Meisn green manure on the quality improvement of maize (Zea mays L.) stover compost. To that end, two field experiments were installed with maize (Zea mays L.) and a successive potato (Solanum tuberosum L.) crop, which was specifically set up to investigate the potential residual effects of tested organo-mineral fertilizers. The potato (Solanum tuberosum L.) crop did not receive any fertilizer, either organic or mineral. The experimental design was a randomized complete block with three replicates. The basic experimental plot was 1.6 m wide and 3 m long (4.8 m²). Treatments under evaluation were: T1=Control, T2=Maize stover co-composted with mineral fertilizer, T3=Maize stover co-compost with Calliandra calothyrsus Meisn green manure; T4=Farm manure+45-60-30; and T5=Maize stover co-composted with Calliandra calothyrsus Meisn green manure+45-60-30. Evaluated parameters were grain yields, root biomass, above-ground biomass, Harvest Index, and Root/Shoot ratio for maize (Zea mays L.). Potato yields were categorized into small size (< 35 mm), medium size (35-65 mm) and big size tubers (> 65 mm). Significant effects (p < 0.001) of tested fertilizer treatments were observed for maize grain yields (GY), above-ground biomass (AGB), and root biomass (RB). No effect (p > 0.05) of fertilizer treatments could be noticed on the harvest index (HI=0.31-0.38) or R/S ratio (0.079-0.088). For the successive potato crop, a significant effect (p < 0.001) of tested treatments was only observed for the seed-oriented medium size tubers (MST) potato yield. Overall, the most relevant observation of the maize experiment is that treatments T4 and T5 gave higher and equivalent grain and biomass yields. From there, we derive that maize stover co-composted with Calliandra calothyrsus Meisn green manure could be a sound substitute to farm manure. Additionally, the potato experiment highlighted the residual effects of the T3 treatment, statistically equivalent to that of T2. Consequently, we advise that the effects of compost-based organo-mineral fertilizers on crop yields should be evaluated beyond a single seasonal crop, in order to fully catch their residual fertilizer potentials. &nbsp